Filamentous proteins that are the main constituent of the thin filaments of muscle fibers. The filaments (known also as filamentous or F-actin) can be dissociated into their globular subunits; each subunit is composed of a single polypeptide 375 amino acids long. This is known as globular or G-actin. In conjunction with MYOSINS, actin is responsible for the contraction and relaxation of muscle.
Fibers composed of MICROFILAMENT PROTEINS, which are predominately ACTIN. They are the smallest of the cytoskeletal filaments.
A family of low MOLECULAR WEIGHT actin-binding proteins found throughout eukaryotes. They remodel the actin CYTOSKELETON by severing ACTIN FILAMENTS and increasing the rate of monomer dissociation.
Actin capping proteins are cytoskeletal proteins that bind to the ends of ACTIN FILAMENTS to regulate actin polymerization.
The network of filaments, tubules, and interconnecting filamentous bridges which give shape, structure, and organization to the cytoplasm.
Very toxic polypeptide isolated mainly from AMANITA phalloides (Agaricaceae) or death cup; causes fatal liver, kidney and CNS damage in mushroom poisoning; used in the study of liver damage.
Reduced (protonated) form of THIAZOLES. They can be oxidized to THIAZOLIDINEDIONES.
A 90-kDa protein produced by macrophages that severs ACTIN filaments and forms a cap on the newly exposed filament end. Gelsolin is activated by CALCIUM ions and participates in the assembly and disassembly of actin, thereby increasing the motility of some CELLS.
A family of low molecular weight proteins that bind ACTIN and control actin polymerization. They are found in eukaryotes and are ubiquitously expressed.
A fungal metabolite that blocks cytoplasmic cleavage by blocking formation of contractile microfilament structures resulting in multinucleated cell formation, reversible inhibition of cell movement, and the induction of cellular extrusion. Additional reported effects include the inhibition of actin polymerization, DNA synthesis, sperm motility, glucose transport, thyroid secretion, and growth hormone release.
A diverse superfamily of proteins that function as translocating proteins. They share the common characteristics of being able to bind ACTINS and hydrolyze MgATP. Myosins generally consist of heavy chains which are involved in locomotion, and light chains which are involved in regulation. Within the structure of myosin heavy chain are three domains: the head, the neck and the tail. The head region of the heavy chain contains the actin binding domain and MgATPase domain which provides energy for locomotion. The neck region is involved in binding the light-chains. The tail region provides the anchoring point that maintains the position of the heavy chain. The superfamily of myosins is organized into structural classes based upon the type and arrangement of the subunits they contain.
A class of saturated compounds consisting of two rings only, having two or more atoms in common, containing at least one hetero atom, and that take the name of an open chain hydrocarbon containing the same total number of atoms. (From Riguady et al., Nomenclature of Organic Chemistry, 1979, p31)
A complex of seven proteins including ARP2 PROTEIN and ARP3 PROTEIN that plays an essential role in maintenance and assembly of the CYTOSKELETON. Arp2-3 complex binds WASP PROTEIN and existing ACTIN FILAMENTS, and it nucleates the formation of new branch point filaments.
Proteins which participate in contractile processes. They include MUSCLE PROTEINS as well as those found in other cells and tissues. In the latter, these proteins participate in localized contractile events in the cytoplasm, in motile activity, and in cell aggregation phenomena.
A dynamic actin-rich extension of the surface of an animal cell used for locomotion or prehension of food.
A protein found in the thin filaments of muscle fibers. It inhibits contraction of the muscle unless its position is modified by TROPONIN.
Major constituent of the cytoskeleton found in the cytoplasm of eukaryotic cells. They form a flexible framework for the cell, provide attachment points for organelles and formed bodies, and make communication between parts of the cell possible.
A PROFILIN binding domain protein that is part of the Arp2-3 complex. It is related in sequence and structure to ACTIN and binds ATP.
A component of the Arp2-3 complex that is related in sequence and structure to ACTIN and that binds ATP. It is expressed at higher levels than ARP2 PROTEIN and does not contain a PROFILIN binding domain.
The species Oryctolagus cuniculus, in the family Leporidae, order LAGOMORPHA. Rabbits are born in burrows, furless, and with eyes and ears closed. In contrast with HARES, rabbits have 22 chromosome pairs.
The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.
Chemical reaction in which monomeric components are combined to form POLYMERS (e.g., POLYMETHYLMETHACRYLATE).
A protein complex of actin and MYOSINS occurring in muscle. It is the essential contractile substance of muscle.
Microscopy of specimens stained with fluorescent dye (usually fluorescein isothiocyanate) or of naturally fluorescent materials, which emit light when exposed to ultraviolet or blue light. Immunofluorescence microscopy utilizes antibodies that are labeled with fluorescent dye.
A protein factor that regulates the length of R-actin. It is chemically similar, but immunochemically distinguishable from actin.
Compounds formed by the joining of smaller, usually repeating, units linked by covalent bonds. These compounds often form large macromolecules (e.g., BIOPOLYMERS; PLASTICS).
Compounds consisting of chains of AMINO ACIDS alternating with CARBOXYLIC ACIDS via ester and amide linkages. They are commonly cyclized.
A member of the Wiskott-Aldrich syndrome protein family that is found at high levels in NERVE CELLS. It interacts with GRB2 ADAPTOR PROTEIN and with CDC42 PROTEIN.
Polymers synthesized by living organisms. They play a role in the formation of macromolecular structures and are synthesized via the covalent linkage of biological molecules, especially AMINO ACIDS; NUCLEOTIDES; and CARBOHYDRATES.
WASP protein is mutated in WISKOTT-ALDRICH SYNDROME and is expressed primarily in hematopoietic cells. It is the founding member of the WASP protein family and interacts with CDC42 PROTEIN to help regulate ACTIN polymerization.
A large family of MONOMERIC GTP-BINDING PROTEINS that are involved in regulation of actin organization, gene expression and cell cycle progression. This enzyme was formerly listed as EC
11- to 14-membered macrocyclic lactones with a fused isoindolone. Members with INDOLES attached at the C10 position are called chaetoglobosins. They are produced by various fungi. Some members interact with ACTIN and inhibit CYTOKINESIS.
The movement of cells from one location to another. Distinguish from CYTOKINESIS which is the process of dividing the CYTOPLASM of a cell.
Microscopy using an electron beam, instead of light, to visualize the sample, thereby allowing much greater magnification. The interactions of ELECTRONS with specimens are used to provide information about the fine structure of that specimen. In TRANSMISSION ELECTRON MICROSCOPY the reactions of the electrons that are transmitted through the specimen are imaged. In SCANNING ELECTRON MICROSCOPY an electron beam falls at a non-normal angle on the specimen and the image is derived from the reactions occurring above the plane of the specimen.
A member of the Rho family of MONOMERIC GTP-BINDING PROTEINS. It is associated with a diverse array of cellular functions including cytoskeletal changes, filopodia formation and transport through the GOLGI APPARATUS. This enzyme was formerly listed as EC
The subfamily of myosin proteins that are commonly found in muscle fibers. Myosin II is also involved a diverse array of cellular functions including cell division, transport within the GOLGI APPARATUS, and maintaining MICROVILLI structure.
Contractile tissue that produces movement in animals.
Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.
The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.
Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.
A family of crosslinking filament proteins encoded by distinct FLN genes. Filamins are involved in cell adhesion, spreading, and migration, acting as scaffolds for over 90 binding partners including channels, receptors, intracellular signaling molecules and transcription factors. Due to the range of molecular interactions, mutations in FLN genes result in anomalies with moderate to lethal consequences.
A cytoskeletal protein associated with cell-cell and cell-matrix interactions. The amino acid sequence of human vinculin has been determined. The protein consists of 1066 amino acid residues and its gene has been assigned to chromosome 10.
A family of microfilament proteins whose name derives from the fact that mutations in members of this protein family have been associated with WISKOTT-ALDRICH SYNDROME. They are involved in ACTIN polymerization and contain a polyproline-rich region that binds to PROFILIN, and a verprolin homology domain that binds G-ACTIN.
The resistance that a gaseous or liquid system offers to flow when it is subjected to shear stress. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)
The level of protein structure in which combinations of secondary protein structures (alpha helices, beta sheets, loop regions, and motifs) pack together to form folded shapes called domains. Disulfide bridges between cysteines in two different parts of the polypeptide chain along with other interactions between the chains play a role in the formation and stabilization of tertiary structure. Small proteins usually consist of only one domain but larger proteins may contain a number of domains connected by segments of polypeptide chain which lack regular secondary structure.
Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.
Common name for the species Gallus gallus, the domestic fowl, in the family Phasianidae, order GALLIFORMES. It is descended from the red jungle fowl of SOUTHEAST ASIA.
The rate dynamics in chemical or physical systems.
Transport proteins that carry specific substances in the blood or across cell membranes.
A genus of protozoa, formerly also considered a fungus. Its natural habitat is decaying forest leaves, where it feeds on bacteria. D. discoideum is the best-known species and is widely used in biomedical research.
Specialized structures of the cell that extend the cell membrane and project out from the cell surface.
Slender, cylindrical filaments found in the cytoskeleton of plant and animal cells. They are composed of the protein TUBULIN and are influenced by TUBULIN MODULATORS.
A RHO GTP-BINDING PROTEIN involved in regulating signal transduction pathways that control assembly of focal adhesions and actin stress fibers. This enzyme was formerly listed as EC
The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells.
Established cell cultures that have the potential to propagate indefinitely.
The intracellular transfer of information (biological activation/inhibition) through a signal pathway. In each signal transduction system, an activation/inhibition signal from a biologically active molecule (hormone, neurotransmitter) is mediated via the coupling of a receptor/enzyme to a second messenger system or to an ion channel. Signal transduction plays an important role in activating cellular functions, cell differentiation, and cell proliferation. Examples of signal transduction systems are the GAMMA-AMINOBUTYRIC ACID-postsynaptic receptor-calcium ion channel system, the receptor-mediated T-cell activation pathway, and the receptor-mediated activation of phospholipases. Those coupled to membrane depolarization or intracellular release of calcium include the receptor-mediated activation of cytotoxic functions in granulocytes and the synaptic potentiation of protein kinase activation. Some signal transduction pathways may be part of larger signal transduction pathways; for example, protein kinase activation is part of the platelet activation signal pathway.
Proteins which bind calmodulin. They are found in many tissues and have a variety of functions including F-actin cross-linking properties, inhibition of cyclic nucleotide phosphodiesterase and calcium and magnesium ATPases.
A rac GTP-binding protein involved in regulating actin filaments at the plasma membrane. It controls the development of filopodia and lamellipodia in cells and thereby influences cellular motility and adhesion. It is also involved in activation of NADPH OXIDASE. This enzyme was formerly listed as EC
A sub-family of RHO GTP-BINDING PROTEINS that is involved in regulating the organization of cytoskeletal filaments. This enzyme was formerly listed as EC
Protein analogs and derivatives of the Aequorea victoria green fluorescent protein that emit light (FLUORESCENCE) when excited with ULTRAVIOLET RAYS. They are used in REPORTER GENES in doing GENETIC TECHNIQUES. Numerous mutants have been made to emit other colors or be sensitive to pH.
The introduction of a phosphoryl group into a compound through the formation of an ester bond between the compound and a phosphorus moiety.
The parts of a macromolecule that directly participate in its specific combination with another molecule.
Connective tissue cells which secrete an extracellular matrix rich in collagen and other macromolecules.
A cytotoxic member of the CYTOCHALASINS.
Recombinant proteins produced by the GENETIC TRANSLATION of fused genes formed by the combination of NUCLEIC ACID REGULATORY SEQUENCES of one or more genes with the protein coding sequences of one or more genes.
A subclass of myosins found generally associated with actin-rich membrane structures such as filopodia. Members of the myosin type I family are ubiquitously expressed in eukaryotes. The heavy chains of myosin type I lack coiled-coil forming sequences in their tails and therefore do not dimerize.
The process of moving proteins from one cellular compartment (including extracellular) to another by various sorting and transport mechanisms such as gated transport, protein translocation, and vesicular transport.
Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.
A light microscopic technique in which only a small spot is illuminated and observed at a time. An image is constructed through point-by-point scanning of the field in this manner. Light sources may be conventional or laser, and fluorescence or transmitted observations are possible.
A subclass of myosin involved in organelle transport and membrane targeting. It is abundantly found in nervous tissue and neurosecretory cells. The heavy chains of myosin V contain unusually long neck domains that are believed to aid in translocating molecules over large distances.
An adenine nucleotide containing three phosphate groups esterified to the sugar moiety. In addition to its crucial roles in metabolism adenosine triphosphate is a neurotransmitter.
Test for tissue antigen using either a direct method, by conjugation of antibody with fluorescent dye (FLUORESCENT ANTIBODY TECHNIQUE, DIRECT) or an indirect method, by formation of antigen-antibody complex which is then labeled with fluorescein-conjugated anti-immunoglobulin antibody (FLUORESCENT ANTIBODY TECHNIQUE, INDIRECT). The tissue is then examined by fluorescence microscopy.
Compounds that inhibit cell production of DNA or RNA.
An actin capping protein that binds to the pointed-end of ACTIN. It functions in the presence of TROPOMYOSIN to inhibit microfilament elongation.
An anchoring junction of the cell to a non-cellular substrate. It is composed of a specialized area of the plasma membrane where bundles of the ACTIN CYTOSKELETON terminate and attach to the transmembrane linkers, INTEGRINS, which in turn attach through their extracellular domains to EXTRACELLULAR MATRIX PROTEINS.
Compounds and molecular complexes that consist of very large numbers of atoms and are generally over 500 kDa in size. In biological systems macromolecular substances usually can be visualized using ELECTRON MICROSCOPY and are distinguished from ORGANELLES by the lack of a membrane structure.
A basic element found in nearly all organized tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.
The quality of surface form or outline of CELLS.
Cellular uptake of extracellular materials within membrane-limited vacuoles or microvesicles. ENDOSOMES play a central role in endocytosis.
The protein constituents of muscle, the major ones being ACTINS and MYOSINS. More than a dozen accessory proteins exist including TROPONIN; TROPOMYOSIN; and DYSTROPHIN.
A phosphoinositide present in all eukaryotic cells, particularly in the plasma membrane. It is the major substrate for receptor-stimulated phosphoinositidase C, with the consequent formation of inositol 1,4,5-triphosphate and diacylglycerol, and probably also for receptor-stimulated inositol phospholipid 3-kinase. (Kendrew, The Encyclopedia of Molecular Biology, 1994)
The part of a cell that contains the CYTOSOL and small structures excluding the CELL NUCLEUS; MITOCHONDRIA; and large VACUOLES. (Glick, Glossary of Biochemistry and Molecular Biology, 1990)
A group of intracellular-signaling serine threonine kinases that bind to RHO GTP-BINDING PROTEINS. They were originally found to mediate the effects of rhoA GTP-BINDING PROTEIN on the formation of STRESS FIBERS and FOCAL ADHESIONS. Rho-associated kinases have specificity for a variety of substrates including MYOSIN-LIGHT-CHAIN PHOSPHATASE and LIM KINASES.
Proteins that are involved in or cause CELL MOVEMENT such as the rotary structures (flagellar motor) or the structures whose movement is directed along cytoskeletal filaments (MYOSIN; KINESIN; and DYNEIN motor families).
Unstriated and unstriped muscle, one of the muscles of the internal organs, blood vessels, hair follicles, etc. Contractile elements are elongated, usually spindle-shaped cells with centrally located nuclei. Smooth muscle fibers are bound together into sheets or bundles by reticular fibers and frequently elastic nets are also abundant. (From Stedman, 25th ed)
A genus of ameboid protozoa. Characteristics include a vesicular nucleus and the formation of several lodopodia, one of which is dominant at a given time. Reproduction occurs asexually by binary fission.
Models used experimentally or theoretically to study molecular shape, electronic properties, or interactions; includes analogous molecules, computer-generated graphics, and mechanical structures.
Microscopy in which television cameras are used to brighten magnified images that are otherwise too dark to be seen with the naked eye. It is used frequently in TELEPATHOLOGY.
Proteins which are found in membranes including cellular and intracellular membranes. They consist of two types, peripheral and integral proteins. They include most membrane-associated enzymes, antigenic proteins, transport proteins, and drug, hormone, and lectin receptors.
A species of the genus SACCHAROMYCES, family Saccharomycetaceae, order Saccharomycetales, known as "baker's" or "brewer's" yeast. The dried form is used as a dietary supplement.
The quantity of volume or surface area of CELLS.
Reagents with two reactive groups, usually at opposite ends of the molecule, that are capable of reacting with and thereby forming bridges between side chains of amino acids in proteins; the locations of naturally reactive areas within proteins can thereby be identified; may also be used for other macromolecules, like glycoproteins, nucleic acids, or other.
Proteins to which calcium ions are bound. They can act as transport proteins, regulator proteins, or activator proteins. They typically contain EF HAND MOTIFS.
The characteristic 3-dimensional shape of a protein, including the secondary, supersecondary (motifs), tertiary (domains) and quaternary structure of the peptide chain. PROTEIN STRUCTURE, QUATERNARY describes the conformation assumed by multimeric proteins (aggregates of more than one polypeptide chain).
Electrophoresis in which a polyacrylamide gel is used as the diffusion medium.
A family of 3,6-di(substituted-amino)-9-benzoate derivatives of xanthene that are used as dyes and as indicators for various metals; also used as fluorescent tracers in histochemistry.
Adenosine 5'-(trihydrogen diphosphate). An adenine nucleotide containing two phosphate groups esterified to the sugar moiety at the 5'-position.
Different forms of a protein that may be produced from different GENES, or from the same gene by ALTERNATIVE SPLICING.
The larger subunits of MYOSINS. The heavy chains have a molecular weight of about 230 kDa and each heavy chain is usually associated with a dissimilar pair of MYOSIN LIGHT CHAINS. The heavy chains possess actin-binding and ATPase activity.
The long cylindrical contractile organelles of STRIATED MUSCLE cells composed of ACTIN FILAMENTS; MYOSIN filaments; and other proteins organized in arrays of repeating units called SARCOMERES .
A zinc-binding phosphoprotein that concentrates at focal adhesions and along the actin cytoskeleton. Zyxin has an N-terminal proline-rich domain and three LIM domains in its C-terminal half.
The movement of CYTOPLASM within a CELL. It serves as an internal transport system for moving essential substances throughout the cell, and in single-celled organisms, such as the AMOEBA, it is responsible for the movement (CELL MOVEMENT) of the entire cell.
A subtype of striated muscle, attached by TENDONS to the SKELETON. Skeletal muscles are innervated and their movement can be consciously controlled. They are also called voluntary muscles.
A group of enzymes which catalyze the hydrolysis of ATP. The hydrolysis reaction is usually coupled with another function such as transporting Ca(2+) across a membrane. These enzymes may be dependent on Ca(2+), Mg(2+), anions, H+, or DNA.
Toxic proteins produced from the species CLOSTRIDIUM BOTULINUM. The toxins are synthesized as a single peptide chain which is processed into a mature protein consisting of a heavy chain and light chain joined via a disulfide bond. The botulinum toxin light chain is a zinc-dependent protease which is released from the heavy chain upon ENDOCYTOSIS into PRESYNAPTIC NERVE ENDINGS. Once inside the cell the botulinum toxin light chain cleaves specific SNARE proteins which are essential for secretion of ACETYLCHOLINE by SYNAPTIC VESICLES. This inhibition of acetylcholine release results in muscular PARALYSIS.
Proteins obtained from the species SACCHAROMYCES CEREVISIAE. The function of specific proteins from this organism are the subject of intense scientific interest and have been used to derive basic understanding of the functioning similar proteins in higher eukaryotes.
The smaller subunits of MYOSINS that bind near the head groups of MYOSIN HEAVY CHAINS. The myosin light chains have a molecular weight of about 20 KDa and there are usually one essential and one regulatory pair of light chains associated with each heavy chain. Many myosin light chains that bind calcium are considered "calmodulin-like" proteins.
Proteins which are involved in the phenomenon of light emission in living systems. Included are the "enzymatic" and "non-enzymatic" types of system with or without the presence of oxygen or co-factors.
A high molecular weight (220-250 kDa) water-soluble protein which can be extracted from erythrocyte ghosts in low ionic strength buffers. The protein contains no lipids or carbohydrates, is the predominant species of peripheral erythrocyte membrane proteins, and exists as a fibrous coating on the inner, cytoplasmic surface of the membrane.
Elements of limited time intervals, contributing to particular results or situations.
Paxillin is a signal transducing adaptor protein that localizes to FOCAL ADHESIONS via its four LIM domains. It undergoes PHOSPHORYLATION in response to integrin-mediated CELL ADHESION, and interacts with a variety of proteins including VINCULIN; FOCAL ADHESION KINASE; PROTO-ONCOGENE PROTEIN PP60(C-SRC); and PROTO-ONCOGENE PROTEIN C-CRK.
The first continuously cultured human malignant CELL LINE, derived from the cervical carcinoma of Henrietta Lacks. These cells are used for VIRUS CULTIVATION and antitumor drug screening assays.
The process by which the CYTOPLASM of a cell is divided.
A microtubule subunit protein found in large quantities in mammalian brain. It has also been isolated from SPERM FLAGELLUM; CILIA; and other sources. Structurally, the protein is a dimer with a molecular weight of approximately 120,000 and a sedimentation coefficient of 5.8S. It binds to COLCHICINE; VINCRISTINE; and VINBLASTINE.
An enzyme capable of hydrolyzing highly polymerized DNA by splitting phosphodiester linkages, preferentially adjacent to a pyrimidine nucleotide. This catalyzes endonucleolytic cleavage of DNA yielding 5'-phosphodi- and oligonucleotide end-products. The enzyme has a preference for double-stranded DNA.
The assembly of the QUATERNARY PROTEIN STRUCTURE of multimeric proteins (MULTIPROTEIN COMPLEXES) from their composite PROTEIN SUBUNITS.
Direct contact of a cell with a neighboring cell. Most such junctions are too small to be resolved by light microscopy, but they can be visualized by conventional or freeze-fracture electron microscopy, both of which show that the interacting CELL MEMBRANE and often the underlying CYTOPLASM and the intervening EXTRACELLULAR SPACE are highly specialized in these regions. (From Alberts et al., Molecular Biology of the Cell, 2d ed, p792)
The uptake of naked or purified DNA by CELLS, usually meaning the process as it occurs in eukaryotic cells. It is analogous to bacterial transformation (TRANSFORMATION, BACTERIAL) and both are routinely employed in GENE TRANSFER TECHNIQUES.
Cells that line the inner and outer surfaces of the body by forming cellular layers (EPITHELIUM) or masses. Epithelial cells lining the SKIN; the MOUTH; the NOSE; and the ANAL CANAL derive from ectoderm; those lining the RESPIRATORY SYSTEM and the DIGESTIVE SYSTEM derive from endoderm; others (CARDIOVASCULAR SYSTEM and LYMPHATIC SYSTEM) derive from mesoderm. Epithelial cells can be classified mainly by cell shape and function into squamous, glandular and transitional epithelial cells.
Partial proteins formed by partial hydrolysis of complete proteins or generated through PROTEIN ENGINEERING techniques.
A broad category of carrier proteins that play a role in SIGNAL TRANSDUCTION. They generally contain several modular domains, each of which having its own binding activity, and act by forming complexes with other intracellular-signaling molecules. Signal-transducing adaptor proteins lack enzyme activity, however their activity can be modulated by other signal-transducing enzymes
A method used to study the lateral movement of MEMBRANE PROTEINS and LIPIDS. A small area of a cell membrane is bleached by laser light and the amount of time necessary for unbleached fluorescent marker-tagged proteins to diffuse back into the bleached site is a measurement of the cell membrane's fluidity. The diffusion coefficient of a protein or lipid in the membrane can be calculated from the data. (From Segen, Current Med Talk, 1995).
The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.
Agents that emit light after excitation by light. The wave length of the emitted light is usually longer than that of the incident light. Fluorochromes are substances that cause fluorescence in other substances, i.e., dyes used to mark or label other compounds with fluorescent tags.
One of the minor protein components of skeletal muscle. Its function is to serve as the calcium-binding component in the troponin-tropomyosin B-actin-myosin complex by conferring calcium sensitivity to the cross-linked actin and myosin filaments.
The degree of similarity between sequences of amino acids. This information is useful for the analyzing genetic relatedness of proteins and species.
Recording serial images of a process at regular intervals spaced out over a longer period of time than the time in which the recordings will be played back.
An intermediate filament protein found predominantly in smooth, skeletal, and cardiac muscle cells. Localized at the Z line. MW 50,000 to 55,000 is species dependent.
Domesticated bovine animals of the genus Bos, usually kept on a farm or ranch and used for the production of meat or dairy products or for heavy labor.
Measurement of the intensity and quality of fluorescence.
Calcium-dependent cell adhesion proteins. They are important in the formation of ADHERENS JUNCTIONS between cells. Cadherins are classified by their distinct immunological and tissue specificities, either by letters (E- for epithelial, N- for neural, and P- for placental cadherins) or by numbers (cadherin-12 or N-cadherin 2 for brain-cadherin). Cadherins promote cell adhesion via a homophilic mechanism as in the construction of tissues and of the whole animal body.
A genus of free-living soil amoebae that produces no flagellate stage. Its organisms are pathogens for several infections in humans and have been found in the eye, bone, brain, and respiratory tract.
Enzymes that transfer the ADP-RIBOSE group of NAD or NADP to proteins or other small molecules. Transfer of ADP-ribose to water (i.e., hydrolysis) is catalyzed by the NADASES. The mono(ADP-ribose)transferases transfer a single ADP-ribose. POLY(ADP-RIBOSE) POLYMERASES transfer multiple units of ADP-ribose to protein targets, building POLY ADENOSINE DIPHOSPHATE RIBOSE in linear or branched chains.
Conversion of an inactive form of an enzyme to one possessing metabolic activity. It includes 1, activation by ions (activators); 2, activation by cofactors (coenzymes); and 3, conversion of an enzyme precursor (proenzyme or zymogen) to an active enzyme.
The sum of the weight of all the atoms in a molecule.
Proteins found in any species of fungus.
Linear POLYPEPTIDES that are synthesized on RIBOSOMES and may be further modified, crosslinked, cleaved, or assembled into complex proteins with several subunits. The specific sequence of AMINO ACIDS determines the shape the polypeptide will take, during PROTEIN FOLDING, and the function of the protein.
Histochemical localization of immunoreactive substances using labeled antibodies as reagents.
Proteins prepared by recombinant DNA technology.
Identification of proteins or peptides that have been electrophoretically separated by blot transferring from the electrophoresis gel to strips of nitrocellulose paper, followed by labeling with antibody probes.
A continuous cell line of high contact-inhibition established from NIH Swiss mouse embryo cultures. The cells are useful for DNA transfection and transformation studies. (From ATCC [Internet]. Virginia: American Type Culture Collection; c2002 [cited 2002 Sept 26]. Available from
Anchoring points where the CYTOSKELETON of neighboring cells are connected to each other. They are composed of specialized areas of the plasma membrane where bundles of the ACTIN CYTOSKELETON attach to the membrane through the transmembrane linkers, CADHERINS, which in turn attach through their extracellular domains to cadherins in the neighboring cell membranes. In sheets of cells, they form into adhesion belts (zonula adherens) that go all the way around a cell.
Toxic or poisonous substances elaborated by marine flora or fauna. They include also specific, characterized poisons or toxins for which there is no more specific heading, like those from poisonous FISHES.
The repeating contractile units of the MYOFIBRIL, delimited by Z bands along its length.
A class of organic compounds containing four or more ring structures, one of which is made up of more than one kind of atom, usually carbon plus another atom. The heterocycle may be either aromatic or nonaromatic.
Cell lines whose original growing procedure consisted being transferred (T) every 3 days and plated at 300,000 cells per plate (J Cell Biol 17:299-313, 1963). Lines have been developed using several different strains of mice. Tissues are usually fibroblasts derived from mouse embryos but other types and sources have been developed as well. The 3T3 lines are valuable in vitro host systems for oncogenic virus transformation studies, since 3T3 cells possess a high sensitivity to CONTACT INHIBITION.
A rare, X-linked immunodeficiency syndrome characterized by ECZEMA; LYMPHOPENIA; and, recurrent pyogenic infection. It is seen exclusively in young boys. Typically, IMMUNOGLOBULIN M levels are low and IMMUNOGLOBULIN A and IMMUNOGLOBULIN E levels are elevated. Lymphoreticular malignancies are common.
An intermediate filament protein found in most differentiating cells, in cells grown in tissue culture, and in certain fully differentiated cells. Its insolubility suggests that it serves a structural function in the cytoplasm. MW 52,000.
Colloids with a solid continuous phase and liquid as the dispersed phase; gels may be unstable when, due to temperature or other cause, the solid phase liquefies; the resulting colloid is called a sol.
Surface ligands, usually glycoproteins, that mediate cell-to-cell adhesion. Their functions include the assembly and interconnection of various vertebrate systems, as well as maintenance of tissue integration, wound healing, morphogenic movements, cellular migrations, and metastasis.
A group of condensed ring hydrocarbons.
Bulbous enlargement of the growing tip of nerve axons and dendrites. They are crucial to neuronal development because of their pathfinding ability and their role in synaptogenesis.
CELL LINES derived from the CV-1 cell line by transformation with a replication origin defective mutant of SV40 VIRUS, which codes for wild type large T antigen (ANTIGENS, POLYOMAVIRUS TRANSFORMING). They are used for transfection and cloning. (The CV-1 cell line was derived from the kidney of an adult male African green monkey (CERCOPITHECUS AETHIOPS).)
A nonmuscle isoform of myosin type II found predominantly in platelets, lymphocytes, neutrophils and brush border enterocytes.
Proteins and peptides that are involved in SIGNAL TRANSDUCTION within the cell. Included here are peptides and proteins that regulate the activity of TRANSCRIPTION FACTORS and cellular processes in response to signals from CELL SURFACE RECEPTORS. Intracellular signaling peptide and proteins may be part of an enzymatic signaling cascade or act through binding to and modifying the action of other signaling factors.
The outward appearance of the individual. It is the product of interactions between genes, and between the GENOTYPE and the environment.
Structures which are part of the CELL MEMBRANE or have cell membrane as a major part of their structure.
A purely physical condition which exists within any material because of strain or deformation by external forces or by non-uniform thermal expansion; expressed quantitatively in units of force per unit area.
RNA sequences that serve as templates for protein synthesis. Bacterial mRNAs are generally primary transcripts in that they do not require post-transcriptional processing. Eukaryotic mRNA is synthesized in the nucleus and must be exported to the cytoplasm for translation. Most eukaryotic mRNAs have a sequence of polyadenylic acid at the 3' end, referred to as the poly(A) tail. The function of this tail is not known for certain, but it may play a role in the export of mature mRNA from the nucleus as well as in helping stabilize some mRNA molecules by retarding their degradation in the cytoplasm.
One of two types of muscle in the body, characterized by the array of bands observed under microscope. Striated muscles can be divided into two subtypes: the CARDIAC MUSCLE and the SKELETAL MUSCLE.
Proteins that originate from insect species belonging to the genus DROSOPHILA. The proteins from the most intensely studied species of Drosophila, DROSOPHILA MELANOGASTER, are the subject of much interest in the area of MORPHOGENESIS and development.
Enzymes that hydrolyze GTP to GDP. EC 3.6.1.-.
Proteins that are preferentially expressed or upregulated during FETAL DEVELOPMENT.
Within a eukaryotic cell, a membrane-limited body which contains chromosomes and one or more nucleoli (CELL NUCLEOLUS). The nuclear membrane consists of a double unit-type membrane which is perforated by a number of pores; the outermost membrane is continuous with the ENDOPLASMIC RETICULUM. A cell may contain more than one nucleus. (From Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed)
A GTP-BINDING PROTEIN involved in regulating a signal transduction pathway that controls assembly of focal adhesions and actin stress fibers. This enzyme was formerly listed as EC
Protein factors that promote the exchange of GTP for GDP bound to GTP-BINDING PROTEINS.
Proteins that activate the GTPase of specific GTP-BINDING PROTEINS.
A group of enzymes that catalyzes the phosphorylation of serine or threonine residues in proteins, with ATP or other nucleotides as phosphate donors.
Minute projections of cell membranes which greatly increase the surface area of the cell.
A process leading to shortening and/or development of tension in muscle tissue. Muscle contraction occurs by a sliding filament mechanism whereby actin filaments slide inward among the myosin filaments.
The insertion of recombinant DNA molecules from prokaryotic and/or eukaryotic sources into a replicating vehicle, such as a plasmid or virus vector, and the introduction of the resultant hybrid molecules into recipient cells without altering the viability of those cells.
Phosphatidylinositols in which one or more alcohol group of the inositol has been substituted with a phosphate group.
Microscopy in which the object is examined directly by an electron beam scanning the specimen point-by-point. The image is constructed by detecting the products of specimen interactions that are projected above the plane of the sample, such as backscattered electrons. Although SCANNING TRANSMISSION ELECTRON MICROSCOPY also scans the specimen point by point with the electron beam, the image is constructed by detecting the electrons, or their interaction products that are transmitted through the sample plane, so that is a form of TRANSMISSION ELECTRON MICROSCOPY.
Progressive restriction of the developmental potential and increasing specialization of function that leads to the formation of specialized cells, tissues, and organs.
Screening techniques first developed in yeast to identify genes encoding interacting proteins. Variations are used to evaluate interplay between proteins and other molecules. Two-hybrid techniques refer to analysis for protein-protein interactions, one-hybrid for DNA-protein interactions, three-hybrid interactions for RNA-protein interactions or ligand-based interactions. Reverse n-hybrid techniques refer to analysis for mutations or other small molecules that dissociate known interactions.
Carbodiimide cross-linking reagent.
A metallic element that has the atomic symbol Mg, atomic number 12, and atomic weight 24.31. It is important for the activity of many enzymes, especially those involved in OXIDATIVE PHOSPHORYLATION.
A catenin that binds F-ACTIN and links the CYTOSKELETON with BETA CATENIN and GAMMA CATENIN.
The physical characteristics and processes of biological systems.
A white crystal or crystalline powder used in BUFFERS; FERTILIZERS; and EXPLOSIVES. It can be used to replenish ELECTROLYTES and restore WATER-ELECTROLYTE BALANCE in treating HYPOKALEMIA.
Any of the processes by which nuclear, cytoplasmic, or intercellular factors influence the differential control (induction or repression) of gene action at the level of transcription or translation.
Regulatory proteins that act as molecular switches. They control a wide range of biological processes including: receptor signaling, intracellular signal transduction pathways, and protein synthesis. Their activity is regulated by factors that control their ability to bind to and hydrolyze GTP to GDP. EC 3.6.1.-.
Cellular release of material within membrane-limited vesicles by fusion of the vesicles with the CELL MEMBRANE.
The development of anatomical structures to create the form of a single- or multi-cell organism. Morphogenesis provides form changes of a part, parts, or the whole organism.
Proteins found in any species of protozoan.
The study of PHYSICAL PHENOMENA and PHYSICAL PROCESSES as applied to living things.
Spindle-shaped cells with characteristic CONTRACTILE PROTEINS and structures that contribute to the WOUND HEALING process. They occur in GRANULATION TISSUE and also in pathological processes such as FIBROSIS.
Immunologic method used for detecting or quantifying immunoreactive substances. The substance is identified by first immobilizing it by blotting onto a membrane and then tagging it with labeled antibodies.
The injection of very small amounts of fluid, often with the aid of a microscope and microsyringes.
A family of serine-threonine kinases that bind to and are activated by MONOMERIC GTP-BINDING PROTEINS such as RAC GTP-BINDING PROTEINS and CDC42 GTP-BINDING PROTEIN. They are intracellular signaling kinases that play a role the regulation of cytoskeletal organization.
The developmental entity of a fertilized chicken egg (ZYGOTE). The developmental process begins about 24 h before the egg is laid at the BLASTODISC, a small whitish spot on the surface of the EGG YOLK. After 21 days of incubation, the embryo is fully developed before hatching.
Small double-stranded, non-protein coding RNAs (21-31 nucleotides) involved in GENE SILENCING functions, especially RNA INTERFERENCE (RNAi). Endogenously, siRNAs are generated from dsRNAs (RNA, DOUBLE-STRANDED) by the same ribonuclease, Dicer, that generates miRNAs (MICRORNAS). The perfect match of the siRNAs' antisense strand to their target RNAs mediates RNAi by siRNA-guided RNA cleavage. siRNAs fall into different classes including trans-acting siRNA (tasiRNA), repeat-associated RNA (rasiRNA), small-scan RNA (scnRNA), and Piwi protein-interacting RNA (piRNA) and have different specific gene silencing functions.
Resistance and recovery from distortion of shape.
A class of organic compounds that contains a naphthalene moiety linked to a sulfonic acid salt or ester.
A gene silencing phenomenon whereby specific dsRNAs (RNA, DOUBLE-STRANDED) trigger the degradation of homologous mRNA (RNA, MESSENGER). The specific dsRNAs are processed into SMALL INTERFERING RNA (siRNA) which serves as a guide for cleavage of the homologous mRNA in the RNA-INDUCED SILENCING COMPLEX. DNA METHYLATION may also be triggered during this process.
A plant genus in the family LILIACEAE generally growing in temperate areas. The word lily is also used in the common names of many plants of other genera that resemble true lilies. True lilies are erect perennial plants with leafy stems, scaly bulbs, usually narrow leaves, and solitary or clustered flowers.
The fission of a CELL. It includes CYTOKINESIS, when the CYTOPLASM of a cell is divided, and CELL NUCLEUS DIVISION.

Tyrosine phosphorylation is required for actin-based motility of vaccinia but not Listeria or Shigella. (1/20287)

Studies of the actin-based motility of pathogens have provided important insights into the events occurring at the leading edge of motile cells [1] [2] [3]. To date, several actin-cytoskeleton-associated proteins have been implicated in the motility of Listeria or Shigella: vasodilator-stimulated phosphoprotein (VASP), vinculin and the actin-related protein complex of Arp2 and Arp3 [4] [5] [6] [7]. To further investigate the underlying mechanism of actin-tail assembly, we examined the localization of components of the actin cytoskeleton including Arp3, VASP, vinculin and zyxin during vaccinia, Listeria and Shigella infections. The most striking difference between the systems was that a phosphotyrosine signal was observed only at the site of vaccinia actin-tail assembly. Micro-injection experiments demonstrated that a phosphotyrosine protein plays an important role in vaccinia actin-tail formation. In addition, we observed a phosphotyrosine signal on clathrin-coated vesicles that have associated actin-tail-like structures and on endogenous vesicles in Xenopus egg extracts which are able to nucleate actin tails [8] [9]. Our observations indicate that a host phosphotyrosine protein is required for the nucleation of actin filaments by vaccinia and suggest that this phosphoprotein might be associated with cellular membranes that can nucleate actin.  (+info)

Transformation mediated by RhoA requires activity of ROCK kinases. (2/20287)

BACKGROUND: The Ras-related GTPase RhoA controls signalling processes required for cytoskeletal reorganisation, transcriptional regulation, and transformation. The ability of RhoA mutants to transform cells correlates not with transcription but with their ability to bind ROCK-I, an effector kinase involved in cytoskeletal reorganisation. We used a recently developed specific ROCK inhibitor, Y-27632, and ROCK truncation mutants to investigate the role of ROCK kinases in transcriptional activation and transformation. RESULTS: In NIH3T3 cells, Y-27632 did not prevent the activation of serum response factor, transcription of c-fos or cell cycle re-entry following serum stimulation. Repeated treatment of NIH3T3 cells with Y-27632, however, substantially disrupted their actin fibre network but did not affect their growth rate. Y-27632 blocked focus formation by RhoA and its guanine-nucleotide exchange factors Dbl and mNET1. It did not affect the growth rate of cells transformed by Dbl and mNET1, but restored normal growth control at confluence and prevented their growth in soft agar. Y-27632 also significantly inhibited focus formation by Ras, but had no effect on the establishment or maintenance of transformation by Src. Furthermore, it significantly inhibited anchorage-independent growth of two out of four colorectal tumour cell lines. Consistent with these data, a truncated ROCK derivative exhibited weak ability to cooperate with activated Raf in focus formation assays. CONCLUSIONS: ROCK signalling is required for both the establishment and maintenance of transformation by constitutive activation of RhoA, and contributes to the Ras-transformed phenotype. These observations provide a potential explanation for the requirement for Rho in Ras-mediated transformation. Moreover, the inhibition of ROCK kinases may be of therapeutic use.  (+info)

Polarized distribution of Bcr-Abl in migrating myeloid cells and co-localization of Bcr-Abl and its target proteins. (3/20287)

Bcr-Abl plays a critical role in the pathogenesis of Philadelphia chromosome-positive leukemia. Although a large number of substrates and interacting proteins of Bcr-Abl have been identified, it remains unclear whether Bcr-Abl assembles multi-protein complexes and if it does where these complexes are within cells. We have investigated the localization of Bcr-Abl in 32D myeloid cells attached to the extracellular matrix. We have found that Bcr-Abl displays a polarized distribution, colocalizing with a subset of filamentous actin at trailing portions of migrating 32D cells, and localizes on the cortical F-actin and on vesicle-like structures in resting 32D cells. Deletion of the actin binding domain of Bcr-Abl (Bcr-AbI-AD) dramatically enhances the localization of Bcr-Abl on the vesicle-like structures. These distinct localization patterns of Bcr-Abl and Bcr-Abl-AD enabled us to examine the localization of Bcr-Abl substrate and interacting proteins in relation to Bcr-Abl. We found that a subset of biochemically defined target proteins of Bcr-Abl redistributed and co-localized with Bcr-Abl on F-actin and on vesicle-like structures. The co-localization of signaling proteins with Bcr-Abl at its sites of localization supports the idea that Bcr-Abl forms a multi-protein signaling complex, while the polarized distribution and vesicle-like localization of Bcr-Abl may play a role in leukemogenesis.  (+info)

Evidence for F-actin-dependent and -independent mechanisms involved in assembly and stability of the medial actomyosin ring in fission yeast. (4/20287)

Cell division in a number of eukaryotes, including the fission yeast Schizosaccharomyces pombe, is achieved through a medially placed actomyosin-based contractile ring. Although several components of the actomyosin ring have been identified, the mechanisms regulating ring assembly are still not understood. Here, we show by biochemical and mutational studies that the S.pombe actomyosin ring component Cdc4p is a light chain associated with Myo2p, a myosin II heavy chain. Localization of Myo2p to the medial ring depended on Cdc4p function, whereas localization of Cdc4p at the division site was independent of Myo2p. Interestingly, the actin-binding and motor domains of Myo2p are not required for its accumulation at the division site although the motor activity of Myo2p is essential for assembly of a normal actomyosin ring. The initial assembly of Myo2p and Cdc4p at the division site requires a functional F-actin cytoskeleton. Once established, however, F-actin is not required for the maintenance of Cdc4p and Myo2p medial rings, suggesting that the attachment of Cdc4p and Myo2p to the division site involves proteins other than actin itself.  (+info)

Cell growth inhibition by farnesyltransferase inhibitors is mediated by gain of geranylgeranylated RhoB. (5/20287)

Recent results have shown that the ability of farnesyltransferase inhibitors (FTIs) to inhibit malignant cell transformation and Ras prenylation can be separated. We proposed previously that farnesylated Rho proteins are important targets for alternation by FTIs, based on studies of RhoB (the FTI-Rho hypothesis). Cells treated with FTIs exhibit a loss of farnesylated RhoB but a gain of geranylgeranylated RhoB (RhoB-GG), which is associated with loss of growth-promoting activity. In this study, we tested whether the gain of RhoB-GG elicited by FTI treatment was sufficient to mediate FTI-induced cell growth inhibition. In support of this hypothesis, when expressed in Ras-transformed cells RhoB-GG induced phenotypic reversion, cell growth inhibition, and activation of the cell cycle kinase inhibitor p21WAF1. RhoB-GG did not affect the phenotype or growth of normal cells. These effects were similar to FTI treatment insofar as they were all induced in transformed cells but not in normal cells. RhoB-GG did not promote anoikis of Ras-transformed cells, implying that this response to FTIs involves loss-of-function effects. Our findings corroborate the FTI-Rho hypothesis and demonstrate that gain-of-function effects on Rho are part of the drug mechanism. Gain of RhoB-GG may explain how FTIs inhibit the growth of human tumor cells that lack Ras mutations.  (+info)

Association of a myosin immunoanalogue with cell envelopes of Aspergillus fumigatus conidia and its participation in swelling and germination. (6/20287)

A myosin immunoanalogue was identified in conidia of Aspergillus fumigatus by Western blotting, indirect immunofluorescence assay, and gold immunoelectron microscopy with two different antimyosin antibodies. The distribution pattern of this protein was followed during the early stages of germination. A single 180-kDa polypeptide, detected predominantly in a cell envelope extract, was found to cross-react with monoclonal and polyclonal antibodies raised against vertebrate muscle myosin. Immunoelectron microscopy permitted precise localization of this polypeptide, indicating that myosin analogue was mainly distributed along the plasma membrane of resting and swollen conidia. In germinating conidia, indirect immunofluorescence microscopy revealed myosin analogue at the periphery of germ tubes, whereas actin appeared as dispersed punctate structures in the cytoplasm that were more concentrated at the site of germ tube emergence. A myosin ATPase inhibitor, butanedione monoxime, greatly reduced swelling and blocked germination. In contrast, when conidia were treated with cytochalasin B, an inhibitor of actin polymerization, swelling was not affected and germination was only partially reduced. Butanedione monoxime-treated conidia showed accumulation of cytoplasmic vesicles and did not achieve cell wall reorganization, unlike swollen conidia. Collectively, these results suggest an essential role for this myosin analogue in the deposition of cell wall components during germination of A. fumigatus conidia and therefore in host tissue colonization.  (+info)

Yops of Yersinia enterocolitica inhibit receptor-dependent superoxide anion production by human granulocytes. (7/20287)

The virulence plasmid-borne genes encoding Yersinia adhesin A (YadA) and several Yersinia secreted proteins (Yops) are involved in the inhibition of phagocytosis and killing of Yersinia enterocolitica by human granulocytes. One of these Yops, YopH, dephosphorylates multiple tyrosine-phosphorylated proteins in eukaryotic cells and is involved in the inhibition of phagocytosis of Y. enterocolitica by human granulocytes. We investigated whether antibody- and complement-opsonized plasmid-bearing (pYV+) Y. enterocolitica inhibits O2- production by human granulocytes in response to various stimuli and whether YopH is involved. Granulocytes were preincubated with mutant strains unable to express YadA or to secrete Yops or YopH. O2- production by granulocytes during stimulation was assessed by measuring the reduction of ferricytochrome c. PYV+ Y. enterocolitica inhibited O2- production by granulocytes incubated with opsonized Y. enterocolitica or N-formyl-Met-Leu-Phe (f-MLP). This inhibitory effect mediated by pYV did not affect receptor-independent O2- production by granulocytes in response to phorbol myristate acetate, indicating that NADPH activity remained unaffected after activation of protein kinase C. The inhibition of f-MLP-induced O2- production by granulocytes depends on the secretion of Yops and not on the expression of YadA. Insertional inactivation of the yopH gene abrogated the inhibition of phagocytosis of antibody- and complement-opsonized Y. enterocolitica by human granulocytes but not of the f-MLP-induced O2- production by granulocytes or tyrosine phosphorylation of granulocyte proteins. These findings suggest that the specific targets for YopH are not present in f-MLP receptor-linked signal transduction and that other Yop-mediated mechanisms are involved.  (+info)

An RNA switch at the 5' splice site requires ATP and the DEAD box protein Prp28p. (8/20287)

Pre-mRNA splicing requires dramatic RNA rearrangements hypothesized to be catalyzed by ATP-dependent RNA unwindases of the DExD/H box family. In a rearrangement critical for the fidelity of 5' splice site recognition, a base-pairing interaction between the 5' splice site and U1 snRNA must be switched for a mutually exclusive interaction between the 5' splice site and U6 snRNA. By lengthening the U1:5' splice site duplex, we impeded this switch in a temperature-dependent manner and prevented formation of the spliceosome's catalytic core. Using genetics, we identified the DExD/H box protein Prp28p as a potential mediator of the switch. In vitro, the switch requires both Prp28p and ATP. We propose that Prp28p directs isomerization of RNA at the 5' splice site and promotes fidelity in splicing.  (+info)

Pure actin used in research and drug discovery, active actin, actin assay, pyrene actin, fluorescent actin, rhodamine actin, hilyte actin, alexa fluor actin, biotin actin, actin, Actin Protein, Arp2/3 protein, Arp2, Arp3, arp2/3 complex, arp2/3 assay, cofilin, profilin, fodrin, spectrin, tropomyosin, tropomodulin, myosin, actin buffer, actin polymerization buffer, actin cytoskeleton, actin binding proteins, filamin, alpha-actinin, gelsolin.
The heart is a dynamic organ that is made up of multiple cell types including muscle and non-muscle. In general the heart is capable of changing due to many factors including development, physiological response, and pathological conditions. Fibrotic (scarring) and hypertrophic (increase in cell size) diseases of the heart are often associated with messengers (such as calcium (Ca2+)) and pathways that activate proteins normally expressed only in the developing heart. One of these proteins, vascular smooth muscle alpha actin (SMA), is the predominant actin in smooth muscle, but is not normally expressed in the adult heart. However, SMA is activated in response to heart transplant and the associated rejection process (fetal reactivation). The focus of this project is to determine the role of Ca2+ in the regulation of SMA in resident non-muscle cell types of the heart. By using cultured cells we have determined that Ca2+ levels and/or Ca2+ agonists effect previously identified transcription factors ...
Cardiac hypertrophy triggered by mechanical load possesses features in common with growth factor signal transduction. A hemodynamic load provokes rapid expression of the growth factor-inducible nuclear oncogene, c-fos, and certain peptide growth factors specifically stimulate the fetal cardiac genes associated with hypertrophy, even in the absence of load. These include the gene encoding vascular smooth muscle alpha-actin, the earliest alpha-actin expressed during cardiac myogenesis; however, it is not known whether reactivation of the smooth muscle alpha-actin gene occurs in ventricular hypertrophy. We therefore investigated myocardial expression of the smooth muscle alpha-actin gene after hemodynamic overload. Smooth muscle alpha-actin mRNA was discernible 24 h after coarctation and was persistently expressed for up to 30 d. In hypertrophied hearts, the prevalence of smooth muscle alpha-actin gene induction was 0.909, versus 0.545 for skeletal muscle alpha-actin (P less than 0.05). ...
Actin, alpha skeletal muscle is a protein that in humans is encoded by the ACTA1 gene. Actin alpha 1 which is expressed in skeletal muscle is one of six different actin isoforms which have been identified. Actins are highly conserved proteins that are involved in cell motility, structure and integrity. Alpha actins are a major constituent of the contractile apparatus. Skeletal alpha actin expression is induced by stimuli and conditions known to cause muscle formation. Such conditions result in fusion of committed cells (satellite cells) into myotubes, to form muscle fibers. Skeletal actin itself, when expressed, causes expression of several other myogenic genes, which are essential to muscle formation. One key transcription factor that activates skeletal actin gene expression is Serum Response Factor (SRF), a protein that binds to specific sites on the promoter DNA of the actin gene. SRF may bring a number of other proteins to the promoter of skeletal actin, such as andogen receptor, and ...
More than 200 mutations in the skeletal muscle α-actin gene (ACTA1) cause either dominant or recessive skeletal muscle disease. Currently, there are no specific therapies. Cardiac α-actin is 99% identical to skeletal muscle α-actin and the predominant actin isoform in fetal muscle. We previously showed cardiac α-actin can substitute for skeletal muscle α-actin, preventing the early postnatal death of Acta1 knock-out mice, which model recessive ACTA1 disease. Dominant ACTA1 disease is caused by the presence of poison mutant actin protein. Experimental and anecdotal evidence nevertheless indicates that the severity of dominant ACTA1 disease is modulated by the relative amount of mutant skeletal muscle α-actin protein present. Thus, we investigated whether transgenic over-expression of cardiac α-actin in postnatal skeletal muscle could ameliorate the phenotype of mouse models of severe dominant ACTA1 disease. In one model, lethality of ACTA1(D286G). Acta1(+/-) mice was reduced from ∼59% before
Muscle disease caused by mutations in the skeletal muscle alpha-actin gene (ACTA1). Neuromuscul Disord. 2003 Sep; 13(7-8):519-31 ...
ACTC1 encodes cardiac muscle alpha actin. This isoform differs from the alpha actin that is expressed in skeletal muscle, ACTA1. Alpha cardiac actin is the major protein of the thin filament in cardiac sarcomeres, which are responsible for muscle contraction and generation of force to support the pump function of the heart. Cardiac alpha actin is a 42.0 kDa protein composed of 377 amino acids. Cardiac alpha actin is a filamentous protein extending from a complex mesh with cardiac alpha-actinin (ACTN2) at Z-lines towards the center of the sarcomere. Polymerization of globular actin (G-actin) leads to a structural filament (F-actin) in the form of a two-stranded helix. Each actin can bind to four others. The atomic structure of monomeric actin was solved by Kabsch et al., and closely thereafter this same group published the structure of the actin filament. Actins are highly conserved proteins; the alpha actins are found in muscle tissues and are a major constituent of the contractile apparatus. ...
TY - JOUR. T1 - Actin Filament Bundling and Different Nucleating Effects of Mouse Diaphanous-Related Formin FH2 Domains on Actin/ADF and Actin/Cofilin Complexes. AU - Machaidze, Gia. AU - Sokoll, Andrea. AU - Shimada, Atsushi. AU - Lustig, Ariel. AU - Mazur, Antonina. AU - Wittinghofer, Alfred. AU - Aebi, Ueli. AU - Mannherz, Hans Georg. PY - 2010/11/5. Y1 - 2010/11/5. N2 - Mouse Diaphanous-related formins (mDias) are members of the formin protein family that nucleate actin polymerization and subsequently promote filamentous actin (F-actin) elongation by monomer addition to fast-growing barbed ends. It has been suggested that mDias preferentially recruit actin complexed to profilin due to their proline-rich FH1 domains. During filament elongation, dimeric mDias remain attached to the barbed ends by their FH2 domains, which form an anti-parallel ring-like structure enclosing the filament barbed ends. Dimer formation of mDia-FH2 domains is dependent on their N-terminal lasso and linker subdomains ...
TY - JOUR. T1 - WASH phosphorylation balances endosomal versus cortical actin network integrities during epithelial morphogenesis. AU - Tsarouhas, Vasilios. AU - Liu, Dan. AU - Tsikala, Georgia. AU - Fedoseienko, Alina. AU - Zinn, Kai. AU - Matsuda, Ryo. AU - Billadeau, Daniel D.. AU - Samakovlis, Christos. PY - 2019/12/1. Y1 - 2019/12/1. N2 - Filamentous actin (F-actin) networks facilitate key processes like cell shape control, division, polarization and motility. The dynamic coordination of F-actin networks and its impact on cellular activities are poorly understood. We report an antagonistic relationship between endosomal F-actin assembly and cortical actin bundle integrity during Drosophila airway maturation. Double mutants lacking receptor tyrosine phosphatases (PTP) Ptp10D and Ptp4E, clear luminal proteins and disassemble apical actin bundles prematurely. These defects are counterbalanced by reduction of endosomal trafficking and by mutations affecting the tyrosine kinase Btk29A, and the ...
Actin filament dynamics govern many key physiological processes from cell motility to tissue morphogenesis. A central feature of actin dynamics is the capacity of the filament to polymerize and depolymerize at its ends in response to cellular conditions. It is currently thought that filament kinetics can be described by a single rate constant for each end. Here, using direct visualization of single actin filament elongation, we show that actin polymerization kinetics at both filament ends are strongly influenced by proteins that bind to the lateral filament surface. We also show that the less dynamic end, called the pointed-end, has a non-elongating state that dominates the observed filament kinetic asymmetry. Estimates of filament flexibility and Brownian dynamics simulations suggest that the observed kinetic diversity arises from structural alteration. Tuning filament kinetics by exploiting the natural malleability of the actin filament structure may be a ubiquitous mechanism to generate the ...
The current evidence suggests that c-Abl and Arg kinases are activated and recruited by different extracellular stimuli to regulate distinct F-actin structures. Progress has been made in understanding the mechanisms of c-Abl activation by growth factors and the ECM, and in identifying some of the substrates or collaborators of c-Abl in regulating the F-actin cytoskeleton. Because c-Abl is involved in several different F-actin-dependent processes, it is likely to collaborate with other F-actin regulators to determine the dynamic biological output. Multi-protein complexes containing c-Abl or c-Abl substrates may have specific subcellular localization to regulate distinct F-actin structures in various F-actin-dependent processes. Further investigation is now required to characterize the key upstream components in c-Abl cytoskeletal signaling pathways. Moreover, it is important to determine precisely when, where and why the crucial c-Abl substrates are phosphorylated and how this affects the ...
Branched actin networks harness the free energy of actin filament assembly to generate forces required for many important cellular processes (Pollard & Cooper, 2009; Blanchoin et al, 2014). These self‐assembling, cytoskeletal structures push against loads (generally cellular membranes) by promoting nucleation and elongation of actin filaments near the load surface (Pollard et al, 2000). Filament nucleation in branched networks is controlled by membrane‐associated signaling molecules, which recruit nucleation‐promoting factors (NPFs) that, in turn, localize the Arp2/3 complex and stimulate its actin nucleation activity (Pollard et al, 2000; Rotty et al, 2013). Filament elongation near the membrane surface is generally assumed to occur via diffusion‐limited incorporation of actin monomers directly from solution (Pollard et al, 2000), with possible assistance from membrane‐associated actin polymerases, such as formins and Ena/VASP proteins (Dominguez, 2009). The fact that neither formins ...
Interstitial cells in the scars of human myocardial infarctions of different postinfarction times (6 hours to 17 years old) were characterized by antibodies to alpha-smooth muscle actin (ASMA), vimentin, and desmin. Basal lamina deposition was studied with antibodies to the basal lamina protein type …
Anti-Actin Antibody, Alexa Fluor 488 Conjugate clone, from rabbit, ALEXA FLUOR® 488; Synonym: Actin, alpha skeletal muscle, Alpha-actin-1; find Sigma-Aldrich-ABT1485-AF488 MSDS, related peer-reviewed papers, technical documents, similar products & more at Sigma-Aldrich.
Anti-Actin Antibody, clone C4 ascites fluid, clone C4, Chemicon®; Synonym: MAB1501X, MAB1501R; find Sigma-Aldrich-MAB1501 MSDS, related peer-reviewed papers, technical documents, similar products & more at Sigma-Aldrich.
Most fungi and metazoan cells have the capacity to express multiple isoforms of Tpm, resulting from either different gene products or different post-translational modifications. The biophysical properties of each Tpm filament and the specific way in which they interact with actin can differ significantly. This cooperative interaction with the actin polymer is crucial for Tpm function because it regulates interactions with other actin-binding proteins (e.g. myosins and cofilin) (Bryce et al., 2003), as well as the biophysical and/or dynamic properties of the actin filament. Different Tpms are, therefore, able to impart distinct physical properties to different actin filaments and, thereby, dictate their function. As many cell types can express multiple Tpm isoforms, it is crucial for the viability, function and mobility of a cell to recruit the appropriate Tpm to an actin polymer at the correct place and time (Bach et al., 2009). Indeed, we know that different Tpms are sorted to different actin ...
Work in T cells has demonstrated that actin cytoskeleton rearrangement and lipid raft polarization induced by contact with an APC are dependent on Vav1 activity (10-12). Therefore, early signals upstream of actin polymerization that induce Vav1 phosphorylation must exist. Activation receptor 2B4 on NK cells is not likely to provide such early signals because 2B4 phosphorylation is itself dependent on actin polymerization (20). To test if LFA-1 engagement on NK cells can activate Vav1 upstream of cytoskeleton rearrangements, actin polymerization was blocked by treatment with cytochalasin D and Latrunculin A. As shown in Fig. 3 B, these inhibitors did not block the Vav1 phosphorylation induced by SC2-ICAM cells. In contrast, and consistent with the actin polymerization-dependent phosphorylation of 2B4 (20), the enhancement of Vav1 phosphorylation due to coengagement of 2B4 with LFA-1 was blocked by cytochalasin D and Latrunculin A (Fig. 3 B). These results show that these inhibitors were effective ...
TY - JOUR. T1 - Formins. T2 - Processive cappers of growing actin filaments. AU - Watanabe, Naoki. AU - Higashida, Chiharu. PY - 2004/11/15. Y1 - 2004/11/15. N2 - Taking the advantage of single-molecule imaging, our recent study has revealed surprisingly long processive movement of a Formin protein, mDia1, surfing along with the growing end of actin filaments in living cells. This finding provides direct evidence for the ability of Formins to function as processive cappers that has been postulated from several lines of evidence in biochemical studies. With nucleating filaments from the profilin-actin pool, Formins may effectively generate long actin filaments, and contribute to the generation of the specific actin-based structures, that is, the contractile ring in cytokinesis, actin stress fibers in animal cells, and yeast actin cables. Furthermore, Formins have the potential to function as actin polymerization-driven molecular motors. Although much remains to be tested about the role of this ...
Tropomyosin (Tpm) isoforms are the master regulators of the functions of individual actin filaments in fungi and metazoans. Tpms are coiled-coil parallel dimers that form a head-to-tail polymer along the length of actin filaments. Yeast only has two Tpm isoforms, whereas mammals have over 40. Each cytoskeletal actin filament contains a homopolymer of Tpm homodimers, resulting in a filament of uniform Tpm composition along its length. Evidence for this master regulator role is based on four core sets of observation. First, spatially and functionally distinct actin filaments contain different Tpm isoforms, and recent data suggest that members of the formin family of actin filament nucleators can specify which Tpm isoform is added to the growing actin filament. Second, Tpms regulate whole-organism physiology in terms of morphogenesis, cell proliferation, vesicle trafficking, biomechanics, glucose metabolism and organ size in an isoform-specific manner. Third, Tpms achieve these functional outputs ...
TY - JOUR. T1 - Actin mRNA localizes in the absence of protein synthesis. AU - Sundell, C. L.. AU - Singer, R. H.. PY - 1990. Y1 - 1990. N2 - Actin mRNA is localized in chicken embryo fibroblasts to the distal regions of leading lamellae, but not within the ruffling edges. In this investigation we have addressed the role of actin translation in this process. The translocation of actin mRNA to the cell periphery was studied by monitoring the distribution of actin mRNA in cells during spreading. Within 90 min, actin mRNA moved from a perinuclear to a peripheral distribution. Formation of lamellipodia preceded actin mRNA localization, indicating that localization is not a prerequisite for this event. Neither puromycin (which dissociates ribosomes from mRNA) nor cycloheximide (which stabilizes ribosomes on mRNA) had any effect on this movement of actin mRNA. Anchoring of actin mRNA was studied using cells with peripherally localized actin mRNA. No change in actin mRNA localization was observed for ...
Intestinal epithelial barrier is critical for the maintenance of normal gut homeostasis and disruption of this barrier may trigger or exaggerate mucosal inflammation. The actin cytoskeleton is a key regulator of barrier structure and function, controlling the assembly and permeability of epithelial adherens and tight junctions. Epithelial cells express two actin isoforms: a β-cytoplasmic actin and γ-cytoplasmic actin. Our previous in vitro studies demonstrated that these actin isoforms play distinctive roles in establishing the intestinal epithelial barrier, by controlling the organization of different junctional complexes. It remains unknown, whether β-actin and γ-actin have unique or redundant functions in regulating the gut barrier in vivo. To address this question, we selectively knocked out β-actin expression in mouse intestinal epithelium. Mice with intestinal epithelial knockout of β-actin do not display gastrointestinal abnormalities or gross alterations of colonic mucosal architecture.
Cell migration involves a coordinated cycle of plasma membrane protrusion at the leading edge, adhesion site formation under the protrusion, disruption of older adhesion sites at the cell rear, and cytoskeleton contraction against adhesions to yield cell body movement (1). Protrusion is thought to result from actin filament (F-actin) polymerization against the plasma membrane (2), with the polymerization rate regulated by the rate of monomer addition to the fast-growing (barbed) ends of filaments. This may depend on actin-related protein 2/3 (Arp2/3) complex activation, which creates free barbed ends by branching and de novo nucleation of filaments (dendritic nucleation) (3), and on actin depolymerizing factor (ADF) cofilin, which creates free barbed ends by severing preexisting filaments and promoting depolymerization of free filament pointed ends (4). Filament growth is limited by barbed end-capping proteins and depletion of the polymerization-competent pool of actin monomers (5).. We ...
We have shown previously (Schwartz, M. A., and E. J. Luna. 1986. J. Cell Biol. 102: 2067-2075) that actin binds with positive cooperativity to plasma membranes from Dictyostelium discoideum. Actin is polymerized at the membrane surface even at concentrations well below the critical concentration for polymerization in solution. Low salt buffer that blocks actin polymerization in solution also prevents actin binding to membranes. To further explore the relationship between actin polymerization and binding to membranes, we prepared four chemically modified actins that appear to be incapable of polymerizing in solution. Three of these derivatives also lost their ability to bind to membranes. The fourth derivative (EF actin), in which histidine-40 is labeled with ethoxyformic anhydride, binds to membranes with reduced affinity. Binding curves exhibit positive cooperativity, and cross-linking experiments show that membrane-bound actin is multimeric. Thus, binding and polymerization are tightly ...
Disassembly of the epithelial apical junctional complex (AJC), composed of the tight junction (TJ) and adherens junction (AJ), is important for normal tissue remodeling and pathogen-induced disruption of epithelial barriers. Using a calcium depletion model in T84 epithelial cells, we previously found that disassembly of the AJC results in endocytosis of AJ/TJ proteins. In the present study, we investigated the role of the actin cytoskeleton in disassembly and internalization of the AJC. Calcium depletion induced reorganization of apical F-actin into contractile rings. Internalized AJ/TJ proteins colocalized with these rings. Both depolymerization and stabilization of F-actin inhibited ring formation and disassembly of the AJC, suggesting a role for actin filament turnover. Actin reorganization was accompanied by activation (dephosphorylation) of cofilin-1 and its translocation to the F-actin rings. In addition, Arp3 and cortactin colocalized with these rings. F-actin reorganization and disassembly of
Author Summary Actin is one of the best studied, evolutionary conserved and most abundant intracellular proteins. Actin can exists in globular and filamentous functionally distinct forms, and is involved in a variety of biological processes, such as muscle contraction, cell motility, cell division, vesicle and organelle movement, endocytosis, and cell signaling. Here we show a novel function of insect cytoplasmic actin, as an extracellular immune factor. Actin is externalized by insect immune competent cells upon immune challenge with bacteria or bacterial surface components, and once externalized, actin binds with high affinity to the surface of bacteria. A functional role of actins interaction with bacteria is to mediate their killing through either phagocytosis or direct antibacterial action. The globular and filamentous forms of actins appear to play distinct functions as extracellular immune factors. Actin also plays a role as a Plasmodium antagonist as it limits parasite infection of the mosquito
Quantitative and qualitative changes in cellular actin were followed during differentiation of a myeloid leukemia cell line, namely Ml, which was inducible with conditioned medium (CM). During 3 d of incubation with CM, when the Ml cells differentiated to macrophages and lost their mitotic activity, the actin content, F-actin ratio in total actin, and the actin synthesis showed an increase. A greater difference before and after differentiation was found in the ability of G-actin to polymerize. Actin harvested from CM-treated cells showed a greater ability to polymerize, depending on the increased concentration of MgCl2 and/or KCl and proteins, as compared with the actin from untreated Ml cells. Actin harvested from the Mml cell line, a macrophage line, had a particularly high polymerizability with or without CM treatment. In contrast, the actin from the D- subline, which is insensitive to CM, showed almost no polymerization. ...
Fission yeast cells use Arp2/3 complex and formin to assemble diverse filamentous actin (F-actin) networks within a common cytoplasm for endocytosis, division, and polarization. Although these homeostatic F-actin networks are usually investigated separately, competition for a limited pool of actin monomers (G-actin) helps to regulate their size and density. However, the mechanism by which G-actin is correctly distributed between rival F-actin networks is not clear. Using a combination of cell biological approaches and in vitro reconstitution of competition between actin assembly factors, we found that the small G-actin binding protein profilin directly inhibits Arp2/3 complex-mediated actin assembly. Profilin is therefore required for formin to compete effectively with excess Arp2/3 complex for limited G-actin and to assemble F-actin for contractile ring formation in dividing cells.
Cell behavior is controlled by extracellular signals that work through signal transduction pathways to regulate the organization of the actin cytoskeleton. Some of these extrinsic signals positively affect the cytoskeleton and induce actin polymerization, but extrinsic signals that negatively regulate and disassemble actin filaments also exist. A family of multidomain proteins, the MICALs, directly associates with Semaphorins, cell surface receptors involved in negative or repulsive cues. Working with purified proteins and in vivo, Hung et al. now find that actin filaments serve as a direct substrate for Micals enzymatic activity. Mical posttranslationally alters actin at its methionine 44 residue, which disrupts the association between actin monomers and cutting actin filaments. Altering the methionine 44 residue makes actin resistant to Mical-mediated disassembly in vitro and in vivo in Drosophila.. R.-J. Hung, C. W. Pak, J. R. Terman, Direct redox regulation of F-actin assembly and ...
Actin plays a major role in the structural integrity and motility of cells as well as in the intracellular dynamics of other macromolecules. Photon Correlation Spectroscopy (PCS) has been used to monitor the diffusion of polystyrene latex spheres (PLS) of different sizes within in vitro polymerized actin solutions under a variety of conditions. Specific actin-binding proteins were added to regulate the actin filament lengths as well as to cross-link filaments together. PCS measurements give information on the mobility of PLS over probing distances equal to the inverse scattering vector magnitude which range from 40 to 420 nm for the data. Results allow estimation of the mean pore sizes within the actin networks as a function of both actin concentration (0.4 - 5 mg/ml) and the presence of actin-binding proteins. Probe diffusion coefficients were measured for PLS samples in length-regulated actin networks at a fixed actin concentration, c (0.65 mg/ml) as c*, the semi-dilute overlap concentration, ...
The connection between T cell activation, plasma membrane order and actin filament dynamics was the main focus of this study. Laurdan and di-4-ANEPPDHQ, membrane order sensing probes, were shown to report only on lipid packing rather than being influenced by the presence of membrane-inserted peptides justifying their use in membrane order studies. These dyes were used to follow plasma membrane order in live cells at 37°C. Disrupting actin filaments had a disordering effect while stabilizing actin filaments had an ordering effect on the plasma membrane, indicating there is a basal level of ordered domains in resting cells. Lowering PI(4,5)P2 levels decreased the proportion of ordered domains strongly suggesting that the connection of actin filaments to the plasma membrane is responsible for the maintaining the level of ordered membrane domains. Membrane blebs, which are detached from the underlying actin filaments, contained a low fraction of ordered domains. Aggregation of membrane components ...
Actin protein derived from rabbit skeletal muscle supplied at |99% purity. Extensive list of citations and additional actin protein research tools available.
Drosophila Quail protein is required for the completion of fast cytoplasm transport from nurse cells to the oocyte, an event critical for the production of viable oocytes. The abundant network of cytoplasmic filamentous actin, established at the onset of fast transport, is absent in quail mutant egg chambers. Previously, we showed that Quail is a germline-specific protein with sequence homology to villin, a vertebrate actin-regulating protein. In this study, we combined biochemical experiments with observations in egg chambers to define more precisely the function of this protein in the regulation of actin-bundle assembly in nurse cells. We report that recombinant Quail can bind and bundle filamentous actin in vitro in a manner similar to villin at a physiological calcium concentration. In contrast to villin, Quail is unable to sever or cap filamentous actin, or to promote nucleation of new actin filaments at a high calcium concentration. Instead, Quail bundles the filaments regardless of the ...
To address the mechanism behind the altered cytoskeleton organization phenotypes of NAA80-KO cells, we analyzed the recovery rates of cytoskeletal structures in cells treated with the actin-depolymerizing drug latrunculin A (LatA). Within 60 min of LatA treatment the actin appeared to be fully depolymerized in control and NAA80-KO cells, and washout of the drug resulted in the recovery of actin filament structures, but the time of recovery was significantly delayed for NAA80-KO cells compared with control cells (Fig. S6), consistent with a direct role of actin Nt-acetylation in actin polymerization.. We next explored the in vitro effect of actin Nt-acetylation on the polymerization/depolymerization properties of actin alone or in the presence of some of the most common actin-assembly factors in cells. Cytoplasmic actin (a mixture of β and γ isoforms) was purified from control and NAA80-KO cells, and the presence or absence of Nt-acetylation was verified by Western blotting (Fig. 4A) (22). The ...
Dynamic actin network at the leading edge of the cell is linked to the extracellular matrix through focal adhesions (FAs), and at the same time it undergoes retrograde flow with different dynamics in two distinct zones: the lamellipodium (peripheral zone of fast flow), and the lamellum (zone of slow flow located between the lamellipodium and the cell body). Cell migration involves expansion of both the lamellipodium and the lamellum, as well as formation of new FAs, but it is largely unknown how the position of the boundary between the two flow zones is defined, and how FAs and actin flow mutually influence each other. We investigated dynamic relationship between focal adhesions and the boundary between the two flow zones in spreading cells. Nascent FAs first appeared in the lamellipodium. Within seconds after the formation of new FAs, the rate of actin flow decreased locally, and the lamellipodium/lamellum boundary advanced towards the new FAs. Blocking fast actin flow with cytochalasin D resulted in
To test whether the BODIPY-PtdIns(3,4,5)P3‐induced polarizing pseudopod was based on the actin cytoskeleton, cytochalasin B, an actin polymerization inhibitor, was used. When pre‐treated with cytochalasin B (5 μg ml−1) before loading with BODIPY-PtdIns(3,4,5)P3, no polarizing pseudopodia formed. After cell morphological polarization was initiated, but before full retraction of PtdIns(3,4,5)P3 into the uropod (Fig. 3C), cytochalasin B caused withdrawal of the polarizing pseudopod (Fig. 3A) without an accompanying release of BODIPY-PtdIns(3,4,5)P3, which remained immobilized and polarized (Fig. 3Af). Thus, the formation of the polarizing pseudopod was dependent on actin polymerization, but the tethering PtdIns(3,4,5)P3 was not sensitive to cytochalasin B. This latter evidence might not rule out the cytoskeleton as the immobilization tether because, unlike F‐actin in pseudopodia, the cortical actin network is largely resistant to depolymerization by cytochalasins (Sheterline et al., 1986, ...
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Background Podocyte foot process effacement accompanied by actin cytoskeleton rearrangements is a cardinal feature of many progressive human proteinuric diseases. Results By microarray profiling of mouse glomerulus, SCHIP1 emerged as one of the most highly enriched transcripts. We detected Schip1 protein in the kidney glomerulus, specifically in podocytes foot processes. Functionally, Schip1 inactivation in zebrafish by morpholino knock-down results in foot process disorganization and podocyte loss leading to proteinuria. In cultured podocytes Schip1 localizes to cortical actin-rich regions of lamellipodia, where it forms a complex with Nherf2 and ezrin, proteins known to participate in actin remodeling stimulated by PDGF beta signaling. Mechanistically, overexpression of Schip1 in vitro causes accumulation of cortical F-actin with dissolution of transversal stress fibers and promotes cell migration in response to PDGF-BB stimulation. Upon actin disassembly by latrunculin A treatment, Schip1 ...
Nuclear actin participates in many essential cellular processes including gene transcription, chromatin remodelling and mRNA processing. Actin shuttles into and out the nucleus through the action of dedicated transport receptors importin-9 and exportin-6, but how this transport is regulated remains unclear. Here, we show that RASSF1A is a novel regulator of actin nucleocytoplasmic trafficking and is required for the active maintenance of nuclear actin levels through supporting binding of exportin-6 (XPO6) to RAN GTPase. RASSF1A (Ras association domain family 1 isoform A) is a tumour suppressor gene frequently silenced by promoter hypermethylation in all major solid cancers. Specifically, we demonstrate that endogenous RASSF1A localises to the nuclear envelope (NE) and is required for nucleocytoplasmic actin transport and the concomitant regulation of myocardin-related transcription factor A (MRTF-A), a co-activator of the transcription factor serum response factor (SRF). The RASSF1A/RAN/XPO6/nuclear
TY - JOUR. T1 - mDia1 and formins. T2 - Screw cap of the actin filament. AU - Mizuno, Hiroaki. AU - Watanabe, Naoki. N1 - Copyright: Copyright 2013 Elsevier B.V., All rights reserved.. PY - 2012. Y1 - 2012. N2 - Formin homology proteins (formins) are actin nucleation factors which remain bound to the growing barbed end and processively elongate actin filament (F-actin). Recently, we have demonstrated that a mammalian formin mDia1 rotates along the long-pitch helix of Factin during processive elongation (helical rotation) by single-molecule fluorescence polarization. We have also shown processive depolymerization of mDia1-bound Factin during which helical rotation was visualized. In the cell where F-actins are highly cross-linked, formins should rotate during filament elongation. Therefore, when formins are tightly anchored to cellular structures, formins may not elongate F-actin. Adversely, helical rotation of formins might affect the twist of F-actin. Formins could thus control actin elongation ...
Molecular probes that individually recognize the 3′ nontranslated regions of six actin genes were utilized in RNA gel blot hybridizations to detect RNAs complementary to each gene in embryonic and adult tissues of Stronglyocentrotus purpuratus. In addition the probes were used in DNA excess filter hybridizations to estimate the relative contribution of the different actin genes. All six genes produce relatively stable mRNAs, and each displays a characteristic and distinct pattern of expression. On the basis of their expression in the egg, early embryos, or in adult coelomocytes, it is concluded that genes termed CyI, CyIIa, CyIIb, CyIIIa, and CyIIIb encode cytoskeletal actin proteins. Actin gene M gives rise to mRNAs that are found only in tissues containing muscle. Actin genes CyI, CyIIa, CyIIb, and M are expressed in both adult and embryonic tissues, giving rise to transcripts 2.1-2.2 kb in length. Expression of genes CyIIIa and CyIIIb is confined to the embryo. Gene CyIIIa provides the ...
TY - JOUR. T1 - Mutants in the Dictyostelium Arp2/3 complex and chemoattractant-induced actin polymerization. AU - Langridge, Paul D.. AU - Kay, Robert R.. PY - 2007/7/15. Y1 - 2007/7/15. N2 - We have investigated the role of the Arp2/3 complex in Dictyostelium cell chemotaxis towards cyclic-AMP and in the actin polymerization that is triggered by this chemoattractant. We confirm that the Arp2/3 complex is recruited to the cell perimeter, or into a pseudopod, after cyclic-AMP stimulation and that this is coincident with actin polymerization. This recruitment is inhibited when actin polymerization is blocked using latrunculin suggesting that the complex binds to pre-existing actin filaments, rather than to a membrane associated signaling complex. We show genetically that an intact Arp2/3 complex is essential in Dictyostelium and have produced partially active mutants in two of its subunits. In these mutants both phases of actin polymerization in response to cyclic-AMP are greatly reduced. One ...
The actin cytoskeleton is crucial for function and morphology of neuronal synapses. Moreover, altered regulation of the neuronal actin cytoskeleton has been implicated in neuropsychiatric diseases such as autism spectrum disorder (ASD). Myosin XVI is a neuronally expressed unconventional myosin known to bind the WAVE regulatory complex (WRC), a regulator of filamentous actin (F-actin) polymerization. Notably, the gene encoding the myosins heavy chain (MYO16) shows genetic association with neuropsychiatric disorders including ASD. Here, we investigated whether myosin XVI plays a role for actin cytoskeleton regulation in the dendritic spines of cerebellar Purkinje cells (PCs), a neuronal cell type crucial for motor learning, social cognition and vocalization. We provide evidence that both myosin XVI and the WRC component WAVE1 localize to PC spines. Fluorescence recovery after photobleaching (FRAP) analysis of GFP-actin in cultured PCs shows that Myo16 knockout as well as PC-specific Myo16 knockdown,
TGF-β-induced antimitotic signals are highly regulated during cell proliferation under normal and pathological conditions, such as liver regeneration and cancer. Up-regulation of the transcriptional cofactors Ski and SnoN during liver regeneration may favor hepatocyte proliferation by inhibiting TGF-β signals. In this study, we found a novel mechanism that regulates Ski protein stability through TGF-β and G protein-coupled receptor (GPCR) signaling. Ski protein is distributed between the nucleus and cytoplasm of normal hepatocytes, and the molecular mechanisms controlling Ski protein stability involve the participation of actin cytoskeleton dynamics. Cytoplasmic Ski is partially associated with actin and localized in cholesterol-rich vesicles. Ski protein stability is decreased by TGF-β/Smads, GPCR/Rho signals, and actin polymerization, whereas GPCR/cAMP signals and actin depolymerization promote Ski protein stability. In conclusion, TGF-β and GPCR signals differentially regulate Ski ...
FIG 6 In vitro interaction of occidiofungin with F- and G-actin. (a) Affinity pulldown of actin using alkyne-OF. Lane 1, ladder; lane 2, 100 ng pure F-actin; lane 3, 100 ng pure G-actin; lane 4, empty; lane 5, F-actin treated with alkyne-OF; lane 6, F-actin treated with native occidiofungin; lane 7, F-actin treated with DMSO; lane 8, G-actin treated with alkyne-OF; lane 9, G-actin treated with native occidiofungin; lane 10, G-actin treated with DMSO. (b) Fluorescence microscopy of the effect of occidiofungin treatment on actin filaments visualized by fluorescently labeled phalloidin. (A) Actin filaments treated with solvent blank (DMSO). (B) Actin/native occidiofungin (24 μg actin:4 μg native occidiofungin). (C) Actin/native occidiofungin (24 μg actin:8 μg native occidiofungin). Scale bar, 5 µm. ...
Title:[Comparison of intracellular actin of thymosin alpha-1 and thymic serum factor].,Author:Deschaux P,Doublet A,Fontanges R,Journal:C R Seances Acad Sci III,1982/1/25;294(4):207-10.,Publication typ...
University of Helsinki, Faculty of Biosciences, Department of Biological and Environmental Sciences, Division of genetics and Institute of Biotechnology. The actin cytoskeleton is essential for a large variety of cell biological processes. Actin exists in either a monomeric or a filamentous form, and it is very important for many cellular functions that the local balance between these two actin populations is properly regulated. A large number of proteins participate in the regulation of actin dynamics in the cell, and twinfilin, one of the proteins examined in this thesis, belongs to this category. The second level of regulation involves proteins that crosslink or bundle actin filaments, thereby providing the cell with a certain shape. α-Actinin, the second protein studied, mainly acts as an actin crosslinking protein. Both proteins are conserved in organisms ranging from yeast to mammals. In this thesis, the roles of twinfilin and α-actinin in development were examined using Drosophila ...
The myristoylated form of c-Abl protein, as well as the P210bcr/abl protein, have been shown by indirect immunofluorescence to associate with F-actin stress fibers in fibroblasts. Analysis of deletion mutants of c-Abl stably expressed in fibroblasts maps the domain responsible for this interaction to the extreme COOH-terminus of Abl. This domain mediates the association of a heterologous protein with F-actin filaments after microinjection into NIH 3T3 cells, and directly binds to F-actin in a cosedimentation assay. Microinjection and cosedimentation assays localize the actin-binding domain to a 58 amino acid region, including a charged motif at the extreme COOH-terminus that is important for efficient binding. F-actin binding by Abl is calcium independent, and Abl competes with gelsolin for binding to F- actin. In addition to the F-actin binding domain, the COOH-terminus of Abl contains a proline-rich region that mediates binding and sequestration of G-actin, and the Abl F- and G-actin binding ...
Each myofibril consists of a large number of sarcomeres, the muscle cells smallest functional units.. Each sarcomere consists of a Z-disc in each end and an A-band in the middle. Actin filaments attached to the Z-discs and myosin filaments form the A band. It is the repetitive A-bands that give the characteristic transverse muscle strips seen under a microscope.. Actin and myosin filaments are organised so every myosin filament is surrounded by six actin filaments. The muscle contraction is a result of myosin filaments climbing on actin filaments in each sarcomere.. The actin filaments comprise of several spherical proteins in long helical chains. They consist of the proteins actin, tropomyocin and a troponin complex. All these are essential for muscle contraction.. The myosin filaments are an accumulation of approximately 300 elongated myosin molecules. Each of these proteins has a head on one end. The myosin heads function is to bind and slide on the actin filaments that lie parallel. As ...
Actin plays important roles in many biological processes, such as establishing cell polarization, accommodating protruding and retracting activities of motile cells, maintaining the physical integrity of the cell, and sensing environmental forces. All these processes are facilitated by the dynamical and mechanical properties of actin filaments, and their ability to exert or resist against forces generated in a cellular environment.. Actin filaments can assemble into a variety of architectures, including branched and crosslinked networks, parallel bundles, and anti-parallel contractile fibers. These structures provide architectural specificities for different regions of the cell, and can also organize into more complex actin-based machineries. We aim to understand how the native molecular architectures of actin-based cellular processes give rise to force generation and rigidity-sensing. We use cryo-electron tomography, and develop methodologies allowing for quantitative analysis of cellular actin ...
We describe the preparation of novel fluorescent derivatives of rabbit muscle actin and bovine tubulin, and the use of these derivatives to study the behaviour of actin filaments and microtubules in living Drosophila embryos, in which the nuclei divide at intervals of 8 to 21 min. The fluorescently labelled proteins appear to function normally in vitro and in vivo, and they allow continuous observation of the cytoskeleton in living embryos without perturbing development. By coinjecting labelled actin and tubulin into the early syncytial embryo, the spatial relationships between the distinct filament networks that they form can be followed second by second. The dynamic rearrangements of actin filaments and microtubules observed confirms and extends results obtained from previous studies, in which fixation techniques and specific staining were used to visualize the cytoskeleton in the Drosophila embryo. However, no tested fixation method produces an exact representation of the in vivo microtubule ...
Gelsolin is an actin-modulating protein that severs F-actin, caps the barbed ends of actin filaments preventing monomer exchange, and promotes the nucleation step of actin polymerisation [(PUBMED:14527663), (PUBMED:3023087)]. It can be regulated by Ca2+ and phosphoinositides [(PUBMED:3027569)]. The interaction between gelsolin and tropomyosin modulates actin dynamics [(PUBMED:23844991)]. Gelsolin also plays a role in ciliogenesis [(PUBMED:20393563)]. The structure of gelsolin has been solved [(PUBMED:9288746)]. Villin is an actin-binding protein that is found in a variety of tissues. It is able to bind to the barbed end of actin filaments with high affinity and can sever filaments [(PUBMED:3087992)]. In addition, villins activity is important for actin bundling in certain cell types [(PUBMED:2256904)]. It was first isolated as a major component of the core of intestinal microvilli [(PUBMED:287075)].. Villin/gelsolin family includes other actin-binding proteins such as severin and supervillin ...
Gelsolin is an actin-modulating protein that severs F-actin, caps the barbed ends of actin filaments preventing monomer exchange, and promotes the nucleation step of actin polymerisation [ (PUBMED:14527663) (PUBMED:3023087) ]. It can be regulated by Ca2+ and phosphoinositides [ (PUBMED:3027569) ]. The interaction between gelsolin and tropomyosin modulates actin dynamics [ (PUBMED:23844991) ]. Gelsolin also plays a role in ciliogenesis [ (PUBMED:20393563) ]. The structure of gelsolin has been solved [ (PUBMED:9288746) ]. Villin is an actin-binding protein that is found in a variety of tissues. It is able to bind to the barbed end of actin filaments with high affinity and can sever filaments [ (PUBMED:3087992) ]. In addition, villins activity is important for actin bundling in certain cell types [ (PUBMED:2256904) ]. It was first isolated as a major component of the core of intestinal microvilli [ (PUBMED:287075) ]. Villin/gelsolin family includes other actin-binding proteins such as severin and ...
In striated muscle the actin cytoskeleton is differentiated into myofibrils. or Axitinib muscles diseases. Therefore proper regulation of actin dynamics in striated muscle is crucial for maintenance and assembly of functional myofibrils. Recent studies have got recommended that both enhancers of actin dynamics and stabilizers of actin filaments are essential for sarcomeric actin company. Further investigation from the regulatory system of actin dynamics in striated muscles should be an integral to focusing on how myofibrils develop and work. ? 2010 Wiley-Liss Inc. continues to be used being a model to review set up and function of cross-striated myofibrils [Fyrberg and Beall 1990 Many invertebrates including nematodes annelids and molluscs possess obliquely striated muscles where sarcomeres are aligned obliquely towards the Z-band-like buildings [Rosenbluth 1965 Your body wall structure muscles from the nematode is normally a consultant example and continues to be thoroughly studied using ...
TY - JOUR. T1 - Competition for actin between two distinct F-actin networks defines a bistable switch for cell polarization. AU - Lomakin, Alexis J.. AU - Lee, Kun Chun. AU - Han, Sangyoon J.. AU - Bui, Duyen A.. AU - Davidson, Michael. AU - Mogilner, Alex. AU - Danuser, Gaudenz. PY - 2015/11/1. Y1 - 2015/11/1. N2 - Symmetry-breaking polarization enables functional plasticity of cells and tissues and is yet not well understood. Here we show that epithelial cells, hard-wired to maintain a static morphology and to preserve tissue organization, can spontaneously switch to a migratory polarized phenotype after relaxation of the actomyosin cytoskeleton. We find that myosin II engages actin in the formation of cortical actomyosin bundles and thus makes it unavailable for deployment in the process of dendritic growth normally driving cell motility. Under low-contractility regimes, epithelial cells polarize in a front-back manner owing to the emergence of actin retrograde flows powered by dendritic ...
TY - JOUR. T1 - Evidence That Actin Depolymerization Protects Hippocampal Neurons against Excitotoxicity by Stabilizing [Ca2+]i. AU - Furukawa, Katsutoshi. AU - Smith-Swintosky, Virginia L.. AU - Mattson, Mark P.. PY - 1995/6. Y1 - 1995/6. N2 - Calcium influx through glutamate receptors and voltage-dependent channels mediates an array of functional and structural responses in neurons. However, unrestrained Ca2+ influx can injure and kill neurons; a mechanism implicated in both acute and chronic neurodegenerative disorders. Data reported here indicate that depolymerization of actin filaments can stabilize intracellular free calcium levels ([Ca2+]i) and protect hippocampal neurons against excitotoxic injury. Studies with fluorescein-labeled phalloidin showed that cytochalasin D and glutamate each induced actin filament depolymerization. The microfilament-disrupting agent cytochalasin D protected cultured rat hippocampal neurons against glutamate toxicity, whereas the actin filament-stabilizing ...
The ,italic,ampA,/italic, gene encodes a secreted protein that modulates cell adhesion, actin polymerization, endocytosis, and cell migration. AmpA is secreted into the supernatant during development, and remains cell associated during growth. AmpA loss in growing cells results in an increase in cell adhesion, and a reduction in F actin. Over expression of AmpA reduces adhesion and increases F actin. As a result of these changes in the cytoskeleton and in adhesion, I have shown AmpA influences cell migration. AmpA knockout cells are defective in migration on top of agar compared to wild type. AmpA over expressing cells migrate better than wild type on top of agar. This defect in the knockout can be rescued by placing the cells in a 3D environment where they migrate under agar. Knockout cells migrate better than wild type under these conditions and over expressing cells migrate about the same as wild type. In order to visualize actin dynamics in live cells, wild type, AmpA KO and AmpA ...
CiteSeerX - Scientific documents that cite the following paper: Adenovirus endocytosis requires actin cytoskeleton reorganization mediated by Rho family Gtpases,
The C-type lectin-like receptor 2 (CLEC-2)activates platelets through Src and Syk tyrosine kinases via a single cytoplasmic YxxL motif known as a hem immunoreceptor tyrosine-based activation motif (hemITAM).Here, we demonstrate using sucrose gradient ultracentrifugation and methyl--cyclodextrin treatment that CLEC-2 translocates to lipid rafts upon ligand engagement and that translocation is essential for hemITAM phosphorylation and signal initiation. HemITAM phosphorylation, but not translocation, is also critically dependent on actin polymerization,Rac1 activation, and release of ADP and thromboxane A2 (TxA2). The role of ADP and TxA2 in mediating hosphorylation is dependent on ligand engagement and rac activation but is independent of platelet aggregation. In contrast,tyrosine phosphorylation of the GPVIFcR -chain ITAM, which has 2 YxxL motifs,is independent of actin polymerization and secondary mediators. These results reveal a unique series of proximal events in CLEC-2 phosphorylation ...
In chronic active hepatitis, very strong alpha-SMA staining was detected at the site of piecemeal necrosis and adjacent lobules. A-SMA expression was decreased in some cases after interferon treatment. In cases of transplanted liver biopsies, expression of intralobular alpha-SMA was diffusely increased but showed no correlation with degree of acute rejection. Cirrhotic livers revealed strong alpha-SMA positivity in fibrous septae as well as in the perisinusoidal space of intact hepatocytes at the leading edge of fibrosis. Interlobular bile ducts were concentrically circumscribed by alpha-SMA positive cells in cases of intrahepatic cholelithiasis. In trabecular type hepatocellular carcinomas, most sinusoidal lining cells were positive for alpha-SMA. Most intralobular alpha-SMA positive cells represent, if not all, perisinusoidal cells (PSCs) which are involved in intralobular fibrogenesis in various liver diseases. PMID: 8305144. ...
Purpose: : PAAs are temporary polygonal, hub and spoke arrangements of actin seen in the first few hours of tissue culture while the cells are settling but then are lost. CLANs are also hub and spoke arrangements of actin that are slowly induced in confluent cultures by steroids, TGFbeta and others and persist. We wished to determine whether or not CLANs and PAAs are one in the same thing so that rapidly forming PAAs can legitimately be used as a model for the slower forming CLANs that we know to form in vivo and are associated with glaucoma in a way that is poorly understood. Methods: : We stain actin in TM cells both in vitro and in situ using phalloid-FITC and image cells either with conventional immunofluorescence or by confocal microscopy. We have a large collection of PAAs and CLANs images and from these over 50 images were selected and handed over in a masked fashion to our reading team who used Image J Software (NIH) to measure CLAN and PAA territories, height, circularity, incidence of ...
Manié S, Schmid-Alliana A, Kubar J, Ferrua B, Rossi B 1993 Disruption of microtubule network in human monocytes induces expression of interleukin-1 but not that of interleukin-6 nor tumor necrosis factor-α: Involvement of protein kinase a stimulation J Biol Chem 268:13675-13681 ...
The studies presented here clearly demonstrated that TGF-β1 triggers the nuclear translocation of MRTFs, which activates the two parallel pathways during EMT (Fig. 10 J). One pathway up-regulates the expression of EMT-regulating genes, such as slug, via MRTFs, Smad3, and GCCG-like motifs, leading to dissociation of cell-cell contacts. The other up-regulates the expression of actin cytoskeletal genes via MRTFs, SRF, and CArG box, resulting in remodeling of the actin cytoskeleton.. Recent studies demonstrate that MRTFs associate with monomeric G-actin through their RPEL motifs, which anchor MRTFs in the cytoplasm (Miralles et al., 2003; Posern et al., 2004). Activated Rho reduces the cytoplasmic G-actin pool by enhancing actin polymerization, and then triggers the dissociation of MRTFs from G-actin, resulting in the nuclear translocation of MRTFs. TGF-β1 stimulation enhances the Rho activity in many kinds of epithelial cell lines (Bhowmick et al., 2001, 2003; Tian et al., 2003). We demonstrated ...
Abbkine Scientific Co. Ltd is known for making quality life science products and tools and it recently announced the official launch of its new antibody - the Anti-Plant Actin Mouse Monoclonal Antibody (3T3).. The antibody otherwise known as AT3G12110 antibody is a Plant Actin Antibody, which is an essential component of cell cytoskeleton. The substance also plays a critical role in the streaming of cytoplasmic, determination of cell shape, cell division and extension growth.. The product is available in a liquid solution and hosted by mouse hence, Plant Actin Mouse mAb. The antibody is also a Recombinant Protein immunogen, with plant reactivity. The antibody like many of its other counterparts is affinity-purified from mouse ascites using specific immunogen by affinity-chromatography.. The Anti-Plant Actin Mouse Monoclonal Antibody (3T3) is made solely for research purpose and not intended for clinical or human use. It can also be stored for as long as one year at -20°C from date of ...
The mechanical properties of a cell are defined mainly by the cytoskeleton. One contributor within this three-dimensional structure is the actin cortex which is located underneath the lipid bilayer. It forms a nearly isotropic and densely cross-linked protein network. We present a continuum mechanical formulation for describing the mechanical properties of in vitro model systems based on their micro-structure, i.e. the behavior of a single filament and its spatial arrangement. The network is considered elastic, viscous effects being neglected. Filamentous actin is a biopolymer with a highly nonlinear force-stretch relationship. This can be well described by a worm-like chain model that includes extensibility of the filament, which we call the . β-model. A comparison with experimental data shows good agreement with values for the physically interpretable parameters. To make these properties applicable to three dimensions we used a non-affine micro-sphere network, which accounts for filaments, ...
p,Giardia intestinalis, a human intestinal parasite and member of what is perhaps the earliest-diverging eukaryotic lineage, contains the most divergent eukaryotic actin identified to date and is the first eukaryote known to lack all canonical actin-binding proteins (ABPs). We sought to investigate the properties and functions of the actin cytoskeleton in Giardia to determine whether Giardia actin (giActin) has reduced or conserved roles in core cellular processes. In vitro polymerization of giActin produced filaments, indicating that this divergent actin is a true filament-forming actin. We generated an anti-giActin antibody to localize giActin throughout the cell cycle. GiActin localized to the cortex, nuclei, internal axonemes, and formed C-shaped filaments along the anterior of the cell and a flagella-bundling helix. These structures were regulated with the cell cycle and in encysting cells giActin was recruited to the Golgi-like cyst wall processing vesicles. Knockdown of giActin ...
The Corynebacterium glutamicum ATCC 13032 prophage CGP3 encodes an actin-like protein, AlpC that was shown to be involved in viral DNA transport and efficient viral DNA replication. AlpC binds to an adapter, AlpA that in turn binds to specific DNA sequences, termed alpS sites. Thus, the AlpAC system is similar to the known plasmid segregation system ParMRS. So far it is unclear how the AlpACS system mediates DNA transport and, whether AlpA and AlpC functionally interact. We show here that AlpA modulates AlpC filamentation dynamics in a dual way. Unbound AlpA stimulates AlpC filament disassembly, while AlpA bound to alpS sites allows for AlpC filament formation. Based on these results we propose a simple search and capture model that explains DNA segregation by viral AlpACS DNA segregation system. ...
Classic pulse-chase studies have shown that actin is conveyed in slow axonal transport, but the mechanistic basis for this movement is unknown. Recently, we reported that axonal actin was surprisingly dynamic, with focal assembly/disassembly events (actin hotspots) and elongating polymers along the axon shaft (actin trails). Using a combination of live imaging, superresolution microscopy, and modeling, in this study, we explore how these dynamic structures can lead to processive transport of actin. We found relatively more actin trails elongated anterogradely as well as an overall slow, anterogradely biased flow of actin in axon shafts. Starting with first principles of monomer/filament assembly and incorporating imaging data, we generated a quantitative model simulating axonal hotspots and trails. Our simulations predict that the axonal actin dynamics indeed lead to a slow anterogradely biased flow of the population. Collectively, the data point to a surprising scenario where local assembly ...
SUMMARY, EXPLANATION AND LIMITATIONS:. Actin is an abundant cytoskeletal protein found in all cells. The proteins 42 kD peptide chain assumes two physical forms: globular actin, which may serve as a cytoplasmic storage pool, and fibrous actin, which, in conjunction with myosin, generates muscle contraction. In non-muscle cells, actin appears to be involved in a variety of functions, such as cell motility, exocytosis, and phagocytosis.. Clone: 5C5,F8,C7. Isotype: IgM. Immunogen: N-Terminal decapeptide of alpha skeletal muscle isoform of actin.. Staining pattern: Cytoplasmic.. Positive control: Tissue sample from skeletal muscle.. APPLICATIONS:. This antibody is designed for the specific localization of human Actin, Skeletal Muscle using IHC techniques in formalin-fixed, paraffin-embedded tissue sections.. ...
for the thin filaments on either side of the Z disc 8. Muscle contraction: sarcomere will shorten in length as Z discs come closer together and size of the H band decreases; the thin filaments are overlapping the thick filaments. 9. Sliding filament hypothesis: (1). Myosin heads bind ATP and split it forming ADP and Pi (2). Myosin heads bind to sites on the actin filaments (3). Myosin heads release the Pi allowing the head to bend toward the A band and Pulling the actin filaments with it; this is the power stroke (4).At end of power stroke, myosin head binds a new ATP and releases ADP; myosin head breaks away from the actin filament 10. Cross bridges: temporary union between the myosin and actin filaments 11. Troponin: protein that binds tropomyosin to actin; also is attracted to Ca+2 ions Tropomyosin: double strand of protein; blocks actin binding sites preventing myosin attachment 12. Neuromuscular junction: (1). Neuron releases acetylcholine which binds to Ach receptors on motor end Plate of ...
We have found that Ste20 or Cla4 is required to polarize the actin cytoskeleton and initiate bud emergence. Whereas mutants lacking either kinase can carry out these processes, loss of Ste20 and Cla4 blocks these events, displaying phenotypes like those of cdc42-1 mutants ( Adams et al. 1990). Because results presented here and elsewhere indicate that Cla4 and Ste20 interact and colocalize with Cdc42 at sites of polarized growth ( Adams et al. 1990; Peter et al. 1996; Benton et al. 1997; Leberer et al. 1997), these PAK homologues function as direct signaling effectors of Cdc42 in pathways that promote bud emergence and actin polarization in G1. In contrast, Ste20 and Cla4 are not required for isotropic growth or progression of the nuclear division cycle, indicating that they have primary roles in cell and actin polarization.. Several observations indicate that Ste20 and Cla4 promote bud emergence by executing functions that are at least partially distinct from those carried out by the Cdc42 ...
APPL1- and RAB5-positive signaling endosomes play a crucial role in the activation of AKT in response to extracellular stimuli. Myosin VI (MYO6) and two of its cargo adaptor proteins, GIPC and TOM1/TOM1L2, localize to these peripheral endosomes and mediate endosome association with cortical actin filaments. Loss of MYO6 leads to the displacement of these endosomes from the cell cortex and accumulation in the perinuclear space. Depletion of this myosin not only affects endosome positioning, but also induces actin and lipid remodeling consistent with endosome maturation, including accumulation of F-actin and the endosomal lipid PI(3)P. These processes acutely perturb endosome function, as both AKT phosphorylation and RAC-dependent membrane ruffling were markedly reduced by depletion of either APPL1 or MYO6. These results place MYO6 and its binding partners at a central nexus in cellular signaling linking actin dynamics at the cell surface and endosomal signaling in the cell cortex ...
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SMARCB1 (ENST00000644036.1) at chr22:23786946-23838008 - Homo sapiens SWI/SNF related, matrix associated, actin dependent regulator of chromatin, subfamily b, member 1 (SMARCB1), transcript variant 1, mRNA. (from RefSeq NM_003073) SMARCB1 (ENST00000629690.2) at chr22_KI270879v1_alt:23325-70878 - Homo sapiens SWI/SNF related, matrix associated, actin dependent regulator of chromatin, subfamily b, member 1 (SMARCB1), transcript variant 4, mRNA. (from RefSeq NM_001362877) SMARCB1 (ENST00000647057.1) at chr22:23786983-23834505 - SWI/SNF related, matrix associated, actin dependent regulator of chromatin, subfamily b, member 1 (from HGNC SMARCB1) SMARCB1 (ENST00000646911.1) at chr22:23787258-23826248 - SWI/SNF related, matrix associated, actin dependent regulator of chromatin, subfamily b, member 1 (from HGNC SMARCB1) SMARCB1 (ENST00000646723.1) at chr22:23787182-23834270 - SWI/SNF related, matrix associated, actin dependent regulator of chromatin, subfamily b, member 1 (from HGNC SMARCB1) SMARCB1 ...
TY - JOUR. T1 - Tight coupling between nucleus and cell migration through the perinuclear actin cap. AU - Kim, Dong Hwee. AU - Cho, Sangkyun. AU - Wirtz, Denis. PY - 2014/6. Y1 - 2014/6. N2 - Although eukaryotic cells are known to alternate between advancing episodes of fast and persistent movement and hesitation episodes of low speed and low persistence, the molecular mechanism that controls the dynamic changes in morphology, speed and persistence of eukaryotic migratory cells remains unclear. Here, we show that the movement of the interphase nucleus during random cell migration switches intermittently between two distinct modes-rotation and translocation-that follow with high fidelity the sequential rounded and elongated morphologies of the nucleus and cell body, respectively. Nuclear rotation and translocation mediate the stopand-go motion of the cell through the dynamic formation and dissolution, respectively, of the contractile perinuclear actin cap, which is dynamically coupled to the ...
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Myofilaments (composed of myosin or actin). Filaments are also highly dynamic in nature and far from a static structure that ...
It binds halfway between the nucleotide binding pocket and the actin binding cleft of myosin, predominantly in an actin ... actin activated ATPase 3.9 ± 0.3 μM[9] Rabbit skeletal muscle II basal ATPase 0.50 μM,[23] 0.3 ± 0.03 μM,[9] 0.41 ± 0.03 μM [7] ... Dou Y, Arlock P, Arner A (September 2007). "Blebbistatin specifically inhibits actin-myosin interaction in mouse cardiac muscle ... where myosin heads are in a helical order and interact with each other but not with actin.[17][18][19] ...
Wieland T, Govindan VM (1974). "Phallotoxins bind to actins". FEBS Lett. 46 (1): 351-3. doi:10.1016/0014-5793(74)80404-7. PMID ...
Benjamin, Mushrooms: poisons and panaceas, p. 217 Wieland, Thomas; V.M. Govindan (1974). "Phallotoxins bind to actins". FEBS ...
Actin is also believed to be important. Axe EL, Walker SA, Manifava M, Chandra P, Roderick HL, Habermann A, Griffiths G, ... Kruppa AJ, Kendrick-Jones J, Buss F (2016). "Myosins, Actin and Autophagy". Traffic (Copenhagen, Denmark). 17 (8): 878-90. doi: ... Aguilera MO, Berón W, Colombo MI (2012). "The actin cytoskeleton participates in the early events of autophagosome formation ...
ACTG1: actin, gamma 1 (17q25). *CDC42EP4: CDC42 effector protein 4 (17q25.1). *USH1G: Usher syndrome 1G (autosomal recessive) ( ...
Polymerization of globular actin (G-actin) leads to a structural filament (F-actin) in the form of a two-stranded helix. Each ... Cardiac alpha actin is a 42.0 kDa protein composed of 377 amino acids. Cardiac alpha actin is a filamentous protein extending ... Actins are highly conserved proteins; the alpha actins are found in muscle tissues and are a major constituent of the ... This isoform differs from the alpha actin that is expressed in skeletal muscle, ACTA1. Alpha cardiac actin is the major protein ...
"Actin' Up , Meek Mill , Music Video". MTV Networks. Retrieved July 10, 2012. Martin, Andrew (January 17, 2013). "Video: Wale " ...
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... which share significant amino acid sequence identity to conventional actins. Both actins and ARPs have an actin fold, which is ... and expression of two novel actin genes, actin-like-7A (ACTL7A) and actin-like-7B (ACTL7B), from the familial dysautonomia ... Actin-like protein 7A is a protein that in humans is encoded by the ACTL7A gene. The protein encoded by this gene is a member ... "Entrez Gene: ACTL7A actin-like 7A". Human ACTL7A genome location and ACTL7A gene details page in the UCSC Genome Browser. ...
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... which share significant amino acid sequence identity to conventional actins. Both actins and ARPs have an actin fold, which is ... "Entrez Gene: ACTL6B actin-like 6B". Oma Y, Nishimori K, Harata M (February 2003). "The brain-specific actin-related protein ... Actin-like protein 6B is a protein that in humans is encoded by the ACTL6B gene. The protein encoded by this gene is a member ... Harata M, Mochizuki R, Mizuno S (1999). "Two isoforms of a human actin-related protein show nuclear localization and mutually ...
Unlike the motility of actin-based cells, which is based on polar cytoskeletal elements such as actin monomers or tubulin ... In contrast to actin, MSP lacks an ATP-binding site. However, it was noticed that ATP is required for MSP filament assembly at ... The two main differences between actin and MSP is that MSP does not bind ATP and the lack of polarity in MSP, thus disabling ... Roberts TM, Stewart M (April 2000). "Acting like actin. The dynamics of the nematode major sperm protein (msp) cytoskeleton ...
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She investigated the regulation of actin polymerisation and how cell movement determines polarity and adhesion. She was awarded ... Jockusch, Brigitte M. (2017-01-03). The Actin Cytoskeleton. Springer. ISBN 9783319463711. Hall, Alan; Nobes, Catherine D. (1999 ... where she identified the role of the GTPase CDC42 and effectors in forming actin-rich filopodial extensions. ...
The CH domain is involved in actin binding in some members of the family. However, in calponins there is evidence that the CH ... Hartwig JH (1995). "Actin-binding proteins. 1: Spectrin super family". Protein Prof. 2 (7): 703-800. PMID 7584474. Gimona M, ... Saraste M, Castresana J (1995). "Does Vav bind to F-actin through a CH domain?". FEBS Lett. 374 (2): 149-151. doi:10.1016/0014- ... Calponin homology domain (or CH domain) is a family of actin binding domains found in both cytoskeletal proteins and signal ...
Elongating the actin filament occurs when free-actin (G-actin) bound to ATP associates with the filament. Under physiological ... Association of G-actin into F-actin is regulated by the critical concentration outlined below. Actin polymerization can further ... The critical concentration is the concentration of either G-actin (actin) or the alpha,beta- tubulin complex (microtubules) at ... Profilin induces ATP binding to G-actin so that it can be incorporated onto the positive end of the filament. Two main theories ...
In fact, annexin A-II is itself an actin-binding protein and therefore it can form a region of interaction with actin by means ... Hayes MJ, Rescher U, Gerke V, Moss SE (August 2004). "Annexin-actin interactions". Traffic. 5 (8): 571-6. doi:10.1111/j.1600- ... in the cell membrane and facilitate actin assembly near the membrane. More recently, annexin scaffolding functions have been ... bisphosphate binding protein recruited to actin assembly sites at cellular membranes". J. Cell Sci. 117 (Pt 16): 3473-80. doi: ...
... which share significant amino acid sequence identity to conventional actins. Both actins and ARPs have an actin fold, which is ... Actin-like protein 6A is a protein that in humans is encoded by the ACTL6A gene. This gene encodes a family member of actin- ... Together with beta-actin, it is required for maximal ATPase activity of BRG1, and for the association of the BAF complex with ... "Entrez Gene: ACTL6A actin-like 6A". Saladi SV, Ross K, Karaayvaz M, Tata PR, Mou H, Rajagopal J, Ramaswamy S, Ellisen LW (2017 ...
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BRK1: SCAR/WAVE actin nucleating complex subunit. *BRPF1: bromodomain and PHD finger containing 1 ...
Actin, Basay, Negros Oriental. "2020 NTC FM Stations" (PDF). Retrieved 2021-03-20. "NegOr Catholic radio station ...
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Actin took a slight lead by the Black Buoy, which they extended to be several lengths up on Myosin by Hammersmith Bridge. ... As such the boats were named Actin and Myosin, the proteins which make the two muscle fibres that pull against each other in ... "CUWBC: Actin vs Myosin". The Boat Race Company Limited. 16 December 2019. Retrieved 10 January 2020. "OUBC Trial Eights Crews ... Myosin fought back before Chiswick Bridge to reduce the deficit, but Actin won by around two lengths. Oxford's men's trial race ...
Lee E, De Camilli P (2002). "Dynamin at actin tails". Proc. Natl. Acad. Sci. U.S.A. 99 (1): 161-6. doi:10.1073/pnas.012607799. ... Orth JD, McNiven MA (2003). "Dynamin at the actin-membrane interface". Curr. Opin. Cell Biol. 15 (1): 31-9. doi:10.1016/S0955- ... Dynamins bind many proteins that bind actin and other cytoskeletal proteins. Dynamins can also self-assemble, a process that ... 2003). "Dynamin2 and cortactin regulate actin assembly and filament organization". Curr. Biol. 12 (21): 1852-7. doi:10.1016/ ...
Figure 1 Tying a knot in an actin filament. Explanatory drawings are added in images 3 7. In images 3 and 7, the microscope ...
F-actin homeostasis through transcriptional regulation and proteasome-mediated proteolysis Masayuki Onishi, Kresti Pecani, ... NAA80 is actins N-terminal acetyltransferase and regulates cytoskeleton assembly and cell motility *From the Cover ... Conformational changes in Arp2/3 complex induced by ATP, WASp-VCA, and actin filaments Sofia Espinoza-Sanchez, Lauren Ann ... Cryo-EM reconstruction of AlfA from Bacillus subtilis reveals the structure of a simplified actin-like filament at 3.4-Å ...
"ACTIN 92". This conference focused on the fundamental properties and cellular functions of actin and actin- based ... Basic Properties of the Actin Molecule and Actin-Based Microfilament Systems. * Front Matter Pages 1-1 ... Roberto Colombo, University of Milan (Italy). This third gathering of researchers devoted to the study of actin and actin- ... Evidence for an F-Actin Like Conformation in the ACTIN:DNASE I Complex ...
Actin and its regulatory proteins are the most abundant set of proteins within cells, and they form one of the major cy ... Working with Actin: Methodological Approaches for the Study of Actin in Neurons ... Actin and its regulatory proteins are the most abundant set of proteins within cells, and they form one of the major ... Neurobiology of Actin: From Neurulation to Synaptic Function opens with a chapter that presents the fundamental concepts ...
In muscle, two long strands of actin molecules are twisted together to form a thin filament, bundles of which alternate with ... The temporary fusion of actin and myosin results in muscle contraction. ... Actin, protein that is an important contributor to the contractile property of muscle and other cells. ... It exists in two forms: G-actin (monomeric globular actin) and F-actin (polymeric fibrous actin), the form involved in muscle ...
Actin-accumulation myopathy is a disorder that primarily affects skeletal muscles, which are muscles that the body uses for ... ACTA1 gene mutations that cause actin-accumulation myopathy may affect the way the skeletal α-actin protein binds to ATP. ATP ... This gene provides instructions for making a protein called skeletal alpha (α)-actin, which is a member of the actin protein ... Mutations in the skeletal muscle alpha-actin gene in patients with actin myopathy and nemaline myopathy. Nat Genet. 1999 Oct;23 ...
The actin filament (F-actin) is composed of actin monomers (G-actin) polymerized head-to-tail to form two intertwining helical ... Figure 6: Electron microscopy of F-actin ± Hsp27. Negative staining images of 2 M actin (a) and 2 M actin plus 6 M Hsp27 (b) ... EM images of F-actin-Hsp27 demonstrated that Hsp27 is not a strong G-actin sequester. Thus, Hsp27, in vitro, is a weak F-actin ... AnB where A is the actin protomer in F-actin, B is Hsp27 irrespective of its oligomeric state, and n is the actin/Hsp27 molar ...
The assembly of polymerized actin with motor proteins at DNA breaks in the nucleus supports the mobility and repair of DNA. ... Actin proteins assemble to protect the genome. The assembly of polymerized actin with motor proteins at DNA breaks in the ... Figure 1 , Nuclear actin polymerizes to preserve genome stability. DNA is packaged with proteins in the nucleus to form a ... Actin filaments form in the nuclei of mammalian cells in response to DNA damage8,9, but their function in DNA repair has also ...
... beta actin ACTC1 - actin, alpha, cardiac muscle 1 ACTG1 - gamma actin 1 ACTG2 - gamma actin 2, smooth muscle, enteric Actin ... In this way there are three species of actin in a filament: ATP-Actin, ADP+Pi-Actin and ADP-Actin. The amount of each one of ... of monomeric G-actin. The Arp2/3 complex binds to actin filaments at 70 degrees to form new actin branches off existing actin ... Cellular actin has two forms: monomeric globules called G-actin and polymeric filaments called F-actin (that is, as filaments ...
Actin definition, a globulin that is present in muscle plasma and that in connection with myosin plays an important role in ... actin. in Medicine. actin. [ăk′tĭn]. n.. *One of the protein components found in muscle, existing as F-actin or G-actin, into ... actin. Historical Examples. of actin. *. "The mares actin as if shed a cup of tea, too," muttered her companion, Ned. ... actin. in Science. actin. [ăk′tĭn]. *A protein found in all eukaryotic cells, forming filaments that make up a main component ...
A list of US medications equivalent to Cipla-Actin is available on the website. ... Cipla-Actin is a medicine available in a number of countries worldwide. ... Cipla-Actin may be available in the countries listed below.. Ingredient matches for Cipla-Actin. Cyproheptadine. Cyproheptadine ... hydrochloride (a derivative of Cyproheptadine) is reported as an ingredient of Cipla-Actin in the following countries:. *South ...
The actin patch is a highly dynamic actin structure in fungi required primarily for endocytosis but possibly also coupled to ... Actin patches are highly motile, they first assemble at sites of polarized cell growth and then move slowly and ...
Actin-binding proteins (ABPs) aid in the transformation of actin filaments throughout the actin remodeling process. These ... It exists in two forms within eukaryotic cells: globular or G-actin and filament/filamentous or F-actin. Globular actin is the ... Within the cell, the concentrations of G-actin and F-actin continuously fluctuate. The assembly and disassembly of F-actin is ... Simultaneously, older G-actin monomers "fall off" of the pointed end of the microfilament. At the "pointed end" of the F-actin ...
Actin-propelled invasive membrane protrusions promote fusogenic protein engagement during cell-cell fusion. ... Actin-propelled[All Fields] AND Invasive[All Fields] AND ("membranes"[MeSH Terms] OR "membranes"[All Fields] OR "membrane"[All ... Search: Actin-propelled Invasive Membrane Protrusions *. Format. Summary. Summary (text). Abstract. Abstract (text). MEDLINE. ...
... This site provides a simple Java applet to build and study the structure of an actin filament. ... Build Your Own Actin Filament is categorized in the following disciplines: * Science and Technology/Biology/Cell and Molecular ... You just viewed Build Your Own Actin Filament. Please take a moment to rate this material. ...
... Celine Alkemade. Collaborators: Gijsje Koenderink (AMOLF), Anna Akhmanova (University ... The actin and microtubule (MT) cytoskeletons are key structural components that allow and coordinate rapid and sometimes ... For example, we have control over density, geometry, and crosslinking of the actin network, as is shown in Figure 2. Coupling ... For a more profound and quantitative understand of actin-MT crosstalk, we use a simple yet realistic reconstituted model system ...
... into the Act88F flight muscle-specific actin gene. We challenged these variant actins to replace the native protein by ... Functional nonequivalence of Drosophila actin isoforms.. Fyrberg EA1, Fyrberg CC, Biggs JR, Saville D, Beall CJ, Ketchum A. ... We conclude that actin isoform sequences are not equivalent and that effects of the amino acid replacements, while minor ... We sequenced the six genes that encode conventional Drosophila actins and found that they specify amino acid replacements in 27 ...
Actin-like protein 6A (ACL6A, also known as BAF53A) is a subunit of the ATP-dependent SWI/SNF-like BAF chromatin remodelling ...
Novel actin-related proteins Arp-T1 and Arp-T2 as components of the cytoskeletal calyx of the mammalian sperm head.. Exp. Cell ... Arp-T1 is an actin-related protein (Arp) that serves as a component of the cytoskeletal calyx of the mammalian sperm head [PMID ...
Liquid behavior of cross-linked actin bundles. Kimberly L. Weirich, Shiladitya Banerjee, Kinjal Dasbiswas, Thomas A. Witten, ... Liquid behavior of cross-linked actin bundles. Kimberly L. Weirich, Shiladitya Banerjee, Kinjal Dasbiswas, Thomas A. Witten, ... Liquid behavior of cross-linked actin bundles. Kimberly L. Weirich, Shiladitya Banerjee, Kinjal Dasbiswas, Thomas A. Witten, ... A dynamic actin-dependent nucleoskeleton and cell identity. Tomas Venit, Nadine Hosny El Said, Syed Raza Mahmood, Piergiorgio ...
Besides the actin cytoskeleton, there are intermediate filaments... ... actin (thing). See all of actin, there is 1 more in this node. ... The actin cytoskeleton appears under the microscope to be ... The toxin comes from the mushroom Amanita phalloides, and it kills you buy mucking with your actin cytoskeleton. Kids, do not ... A protein that makes up one of the three major structural elements in eukaryotic cells. Besides the actin cytoskeleton, there ...
The actin-binding protein α-actinin, that bundles actin filaments, plays a major role in the organization of the actin network ... Talin contains three actin-filament- (F-actin-) binding domains located in the FERM domain (ABD1), the rod domain (ABD2), and ... Regulation of Actin Assembly by Vinculin. Vinculin is a large actin binding protein of 1066 amino acids present in FAs. ... D. Chereau and R. Dominguez, "Understanding the role of the G-actin-binding domain of Ena/VASP in actin assembly," Journal of ...
... which require actin assembly that is regulated by specialized actin nucleation factors. There is a large variety of different ... Nucleating actin for invasion Nat Rev Cancer. 2011 Mar;11(3):177-87. doi: 10.1038/nrc3003. Epub 2011 Feb 10. ... Studies of the mechanisms of various actin nucleation factors that are involved in cancer cell function may ultimately provide ... actin nucleators in human cells, such as formins, spire and Arp2/3-regulating proteins, and the list is likely to grow. ...
If you know of any papers that use this antibody, please contact us at antibodies [at] alzforum [dot] org for consideration in the References section.. ...
Actin is one of the most abundant eukaryotic proteins. It polymerizes to form filamentous actin (F-actin), which plays a key ... A number of disease-causing mutations in the human ACTA1 gene that encodes skeletal muscle actin affect residues in the most ... Actin plasticity is probably required to accommodate its multiple interactions and functions. The authors suggest that the ... The sequence of eukaryotic actin is highly conserved over evolution. One explanation for this is that the many functions of ...
The process of actin polymerization starts with the association of three G-actin monomers into a trimer. ATP-actin then binds ... Actin-binding proteins dictate the formation of either structure since they cross-link actin filaments. Actin filaments have ... The individual subunits of actin (monomers) are known as globular actin, or for short G-actin. The filamentous polymer composed ... Actin occurs in two forms, as a monomer and as a polymer. It is as a polymer, F-actin, that it appears as thin filaments, which ...
immunogen = N-terminal decapeptide of α-smooth muscle actin for 1A4 and with purified rabbit striated muscle actin for 5C5 ...
In this way there are three species of actin in a filament: ATP-Actin, ADP+Pi-Actin and ADP-Actin.[47][60] The amount of each ... are ATP-G-Actin and ADP-F-actin.[28][29]. G-ActinEdit. Scanning electron microscope images indicate that G-actin has a globular ... of monomeric G-actin. The Arp2/3 complex binds to actin filaments at 70 degrees to form new actin branches off existing actin ... Actin. Ribbon diagram of G-actin. ADP bound to actins active site (multi color sticks near center of figure) as well as a ...
... and the breakdown of actin that both play significant roles in cellular mechanisms like migration and adhesion. ... Actin polymerisation research explores the dynamic processes during the growth of actin, via polymerization, ... Alpha actin. Anti-alpha smooth muscle Actin. Conjugated versions. Beta actin. Anti-beta Actin antibody [AC-15]. Conjugated ... Jasplakinolide induces the polymerization of actin and stabilizes actins monomeric form.. Chaetoglobosin A is an actin ...
Actin and Endocytosis in Budding Yeast. Bruce L. Goode, Julian A. Eskin and Beverly Wendland ... Actin and Endocytosis in Budding Yeast. Bruce L. Goode, Julian A. Eskin and Beverly Wendland ... Actin and Endocytosis in Budding Yeast. Bruce L. Goode, Julian A. Eskin and Beverly Wendland ...
  • An actin protein is the monomeric subunit of two types of filaments in cells: microfilaments, one of the three major components of the cytoskeleton, and thin filaments, part of the contractile apparatus in muscle cells. (
  • It is believed that the diverse range of structures formed by actin enabling it to fulfill such a large range of functions is regulated through the binding of tropomyosin along the filaments. (
  • Actin homologs from prokaryotes and archaea polymerize into different helical or linear filaments consisting of one or multiple strands. (
  • In muscle, two long strands of beadlike actin molecules are twisted together to form a thin filament, bundles of which alternate and interdigitate with bundles of thick filaments formed of myosin, the most abundant protein found in muscle. (
  • Myosin works as a motor, hydrolyzing adenosine triphosphate (ATP) to release energy in such a way that a myosin filament moves along an actin filament, causing the two filaments to slide past each other. (
  • Actin filaments are also an important component of the cytoskeleton in various cell types, where they are dynamic structures, continuously assembling and disassembling. (
  • In nonmuscle cells, meshworks of actin filaments play a role in different types of cellular movement. (
  • The name actin-accumulation myopathy derives from characteristic accumulations in muscle cells of filaments composed of a protein called actin . (
  • ATP is a molecule that supplies energy for cells' activities, and is important in the formation of thin filaments from individual actin molecules . (
  • Actin filaments are part of the cytoskeleton and their dynamic structure is involved in the motility and shape change of the cell [ 10 ]. (
  • The protein actin polymerizes to produce filaments that form crosslinked networks in the cytoplasm of cells. (
  • Actin filaments form in the nuclei of mammalian cells in response to DNA damage 8 , 9 , but their function in DNA repair has also been unclear. (
  • They find that nuclear actin polymerizes to form filaments at hetero-chromatic DSB-repair sites, in a process that requires the presence of the protein complex Arp2/3 and its activators (the Scar and Wash proteins). (
  • They observe that Arp2/3 promotes the formation of actin filaments that grow from hetero-chromatic DSBs towards the nuclear periphery. (
  • The nuclear motor proteins myosin I and myosin V then 'walk' the repair sites along the actin filaments (Fig. 1a). (
  • 3 report that, in cells of the fruit fly Drosophila melanogaster , DNA breaks in heterochromatin are moved to the nuclear periphery to ensure correct repair - motor proteins called myosins 'walk' the DNA breaks along filaments made from polymerized actin protein. (
  • The remodeling of actin filaments occurs in a cyclic pattern on cell surfaces and exists as a fundamental aspect to cellular life. (
  • Again triggered by environmental conditions, actin filaments break back down into monomers and the cycle is completed. (
  • Actin-binding proteins (ABPs) aid in the transformation of actin filaments throughout the actin remodeling process. (
  • Possible Mechanisms: De novo nucleation by the Arp2/3 complex, formins, and Spire that forms a trimer[failed verification] Barbed-end uncapping by the removal of barbed-end-capping proteins (CapZ, Hsp70, EPS8) Barbed-end uncapping by actin-binding-proteins that sever actin filaments Elongation Facilitated in vivo by polymerization promoters and barbed-end capping inhibitory proteins. (
  • Besides the actin cytoskeleton , there are intermediate filaments and microtubules . (
  • used electron microscopy of unmodified, frozen-hydrated actin filaments. (
  • The actin filaments provide mechanical support for the cell, determine the cell shape, and enable cell movements through the use of lamellipodia, filopodia, or pseudopodia (cell extensions used for movement). (
  • Actin filaments can also participate in certain cell junctions, such as those in cytoplasmic streaming when the cell cytoplasm is flowing, and in contraction of the cell during cytokinesis (division of the cell cytoplasm following nucleus division). (
  • It is as a polymer, F-actin, that it appears as thin filaments, which are interwoven with thick myosin filaments. (
  • Much like the microtubules, which are also protein structures found in the cytoskeleton, actin filaments are polar and have two oppositely charged ends. (
  • Another important component in filament production is the Arp2/3 complex, which nucleates new actin filaments while bound to existing filaments, thus creating a branched network. (
  • Actin filaments are assembled in two general types of structures: bundles and networks. (
  • Actin-binding proteins dictate the formation of either structure since they cross-link actin filaments. (
  • Actin filaments have the appearance of a double-stranded helix. (
  • In non-muscle actin bundles, the filaments are held together by actin-bundling proteins and/or cationic species so that they are parallel to each other. (
  • Phalloidin inhibits the depolymerization of actin by tightly binding to actin in filaments, which stops them from being able to dissociate. (
  • Cytochalasin has five different forms (A, B, C, D and E), all of which prevent both actin filament assembly and disassembly by binding to the plus ends of the filaments. (
  • The assembly of actin filaments through the polymerization of actin monomers must be fine-tuned by the cell. (
  • This conformation change favors the interaction of certain regulatory proteins--which regulate both actin polymerization and filament disassembly--with actin monomers and filaments. (
  • Some of these extrinsic signals positively affect the cytoskeleton and induce actin polymerization, but extrinsic signals that negatively regulate and disassemble actin filaments also exist. (
  • now find that actin filaments serve as a direct substrate for Mical's enzymatic activity. (
  • Mical posttranslationally alters actin at its methionine 44 residue, which disrupts the association between actin monomers and cutting actin filaments. (
  • A protein involved in redox signaling disassembles actin filaments and alters their reassembly. (
  • The ARP2/3 complex stabilizes F-actin fragments and promotes formation of new actin filaments (3). (
  • actin filaments also participate in muscle contraction. (
  • Actin filaments are called microfilaments to distinguish them from intermediate filaments . (
  • The major structural entity of the cell is called the cytoskeleton, an interior network consisting of three types of protein filaments - actin filaments, intermediate filaments and microtubules. (
  • The organization and dynamics of actin filaments must be precisely controlled during these processes, and consequently defects in regulation of the actin cytoskeleton lead to various diseases including cancer progression, as well as neurological and immunological disorders. (
  • Oxidation of actin filaments by MICAL sabotages protections from cofilin! (
  • Additionally, the modified model is employed to investigate the viscoelastic property of actin-like network by tracking the trajectories of filaments. (
  • actin filaments are on the same axis but may be oriented with the same or opposite polarities and may be packed with different levels of tightness. (
  • However, these filaments do not act individually and an expanding body of evidence emphasises the importance of actin-microtubule crosstalk in orchestrating cytoskeletal dynamics. (
  • This time-lapse series shows that actin filaments "de-branch" in the presence of cortactin and PI(3,5)P 2 . (
  • Branched actin filaments promote several steps in the endocytic pathway, such as vesicle fission and the formation of endosomal tubules. (
  • The researchers found that cortactin uses its N-terminal actin-binding region to latch onto PI(3,5)P 2 and that this interaction led to the release of cortactin from actin filaments. (
  • They play a leading role not only in muscle cells: Actin filaments are one of the most abundant proteins in all mammalian cells. (
  • Note the absence of signal from the red (MitoTracker) and blue (DAPI) fluorophores, but the bright green fluorescence exhibited by the actin filaments. (
  • Inside the cell body, actin cables are composed of short parallel actin filaments, mostly of identical orientations [38]. (
  • At the division site, a cytokinetic ring is composed of short parallel actin filaments, with identical orientations or mixed polarities depending on the stage of cell division [40]. (
  • eEF1A also is involved in regulating the dynamics of microtubules and actin filaments in cytoplasm. (
  • These mutations involved conserved amino acids, were absent in 500 control individuals, and significantly altered metavinculin-mediated cross-linking of actin filaments in an in vitro assay. (
  • Accumulation of actin filaments (in green) at the immunological synapse of a resistant cancer cell in contact with an NK cell (in red). (
  • However, the organization of actin filaments in target cells remains poorly explored. (
  • They revealed that all the cell lines they investigated contain two subpopulations: one showing a very prominent accumulation of actin filaments at the level of the immunological synapse, and one with no such accumulation. (
  • Note the complex two and three-dimensional network of actin filaments and stress fibers that extend throughout the cytoplasm and inhabit the cortex in this cell line. (
  • The cytoskeleton of eukaryotes has three major components: microfilaments (made of the protein actin), intermediate filaments, and microtubules (made of the protein tubulin). (
  • Actin filaments are linked to α-actinin and to membrane through vinculin . (
  • The tail domain of vinculin binds to membrane lipids and to actin filaments. (
  • In muscle , actin is the major component of thin filaments , which, together with the motor protein myosin (which forms thick filaments ), are arranged into actomyosin myofibrils . (
  • Unstimulated spines contained a stable pool of actin filaments near the base of the spine and a more dynamic pool throughout. (
  • Lasting growth required more of the stable actin filaments, which might originate from the enlargement pool. (
  • The findings explain why larger spines have proportionately more glutamate receptors, since the receptors dock to the ends of actin filaments. (
  • Actin is one of the most abundant proteins found in cells, and actin filaments can be readily labeled using fluorescent forms of a naturally occurring protein called phalloidin. (
  • All these processes are facilitated by the dynamical and mechanical properties of actin filaments, and their ability to exert or resist against forces generated in a cellular environment. (
  • Actin filaments can assemble into a variety of architectures, including branched and crosslinked networks, parallel bundles, and anti-parallel contractile fibers. (
  • We coinjected cortical neurons with fluorescently labeled tubulin and phalloidin and used fluorescence time-lapse imaging to analyze interactions between microtubules and actin filaments (F-actin) in cortical growth cones and axons undergoing branching. (
  • Interactions between dynamic microtubules and dynamic actin filaments involve their coordinated polymerization and depolymerization. (
  • These results suggest that interactions between dynamic microtubules and actin filaments are required for axon branching and directed axon outgrowth. (
  • Much of our understanding of how actin filaments and microtubules reorganize during directed axon outgrowth is based on interpretations from fixed preparations. (
  • Therefore, in the present study, we have used the novel approach of visualizing simultaneous changes in both microtubules and actin filaments in relation to one another during different stages of axon branching in living cortical neurons. (
  • Unipolar reorganization of F-actin layer at bacterial division and bundling of actin filaments by plastin correlate with movement of Shigella flexneri within HeLa cells. (
  • Next, the study looked at F-actin filaments, a protein structure which previous studies have shown plays a role in the constriction of ASM, and found that 6-shogaol was effective in speedily dissolving these filaments. (
  • Actin and its regulatory proteins are the most abundant set of proteins within cells, and they form one of the major cytoskeletal systems-the actin filament cytoskeleton. (
  • While much has been learned about the roles of the actin cytoskeleton in non-neuronal cells, our understanding of the full spectrum of the functions of actin in neurons is far from complete. (
  • This book is an introduction to the interface between the actin cytoskeleton and the myriad of issues fundamental to the understanding of nervous system function. (
  • This text is intended for neuroscientists interested in investigating the actin cytoskeleton in the context of their particular neuroscience research program, and its chapters are cross-referenced in order to assist readers in finding relevant information that is covered in greater depth in other chapters. (
  • The beta and gamma actins coexist in most cell types as components of the cytoskeleton, and as mediators of internal cell motility. (
  • Hsp27 is involved in a variety of cellular functions including molecular chaperone activity, control of apoptosis, and regulation of the actin filament cytoskeleton [ 1 - 3 , 5 - 9 ]. (
  • The cell's signaling pathways cause actin to affect intracellular organization of the cytoskeleton and often consequently, the cell membrane. (
  • Due to the control we have in our reconstituted system, we can confront dynamic MTs with different types of actin networks to account for the diversity of cytoskeleton architectures. (
  • Coupling between the two cytoskeleton components is introduced in form of transient binding of actin-MT crosslinkers, or by proteins that interact both with actin and MT plus-end-binding proteins. (
  • The toxin comes from the mushroom Amanita phalloides , and it kills you buy mucking with your actin cytoskeleton . (
  • Proteins from adhesion structures connect the extracellular matrix to the actin cytoskeleton, allowing the growing actin network to push the plasma membrane and the contractile cables (stress fibers) to pull the cell body. (
  • In this cycle, proteins from adhesion structures connect the ECM to the actin cytoskeleton (Figure 1 ), allowing the growing actin network to push the plasma membrane forward and the contractile stress fibers to pull the cell body and retract the tail. (
  • At the molecular level, talin is one of the first proteins involved in the connection between the ECM and the actin cytoskeleton. (
  • Clathrin-mediated endocytosis shuts down during mitosis in eukaryotic cells because all of the required actin is hoarded by the cytoskeleton. (
  • Using two different methods that released some of the actin from the cytoskeleton but did not decrease membrane tension, they demonstrated that it is possible to restart endocytosis. (
  • Cell behavior is controlled by extracellular signals that work through signal transduction pathways to regulate the organization of the actin cytoskeleton. (
  • Actin, a ubiquitous eukaryotic protein, is the major component of the cytoskeleton. (
  • Bundled actin structures play an essential role in the mechanical response of the actin cytoskeleton in eukaryotic cells. (
  • Our group uses a wide range of biophysical, biochemical, cell biological, and genetic approaches to uncover the general principles underlying regulation of the actin cytoskeleton, and to reveal how defects in actin dynamics affect the physiological functions of cells. (
  • In addition, it's generally known that mechanical force plays an important role in the physiology of eukaryote cells whose major structural component in cortex is actin cytoskeleton. (
  • The actin cytoskeleton plays an important role in this growth. (
  • In fungi the actin cytoskeleton is involved in numerous cellular processes including: cell polarity, cytokinesis, endocytosis, exocytosis, bud site selection, cell wall remodelling and cell shape d. (
  • New chapters cover Actin isoforms in cancer, Actin cytoskeleton regulators at invadopodia, Cytoskeletal Mechanics Drives Heterogeneity in Epithelial Ovarian Cancer, and more. (
  • Dustin, M.L. & Cooper, J.A. The immunological synapse and the actin cytoskeleton: molecular hardware for T cell signaling. (
  • The field of cell movement was abuzz with the revelation that non-muscle cells contained actin and myosin, but no one understood the mechanism regulating those cytoskeleton proteins. (
  • Within this laboratory, the "Cytoskeleton and Cancer Progression" research group, led by Dr. Clément Thomas, focuses in particular on the actin cytoskeleton and related signaling pathways in the context of breast cancer. (
  • The actin cytoskeleton is essential for maintaining the shape of cells and enabling motility, and plays critical roles in tumor cell invasion and metastasis. (
  • In the present research work, Dr. Antoun Al Absi, Dr. Thomas and co-workers investigated whether the actin cytoskeleton plays a role in immune evasion. (
  • The scientists thus took a closer look at possible alterations of the actin cytoskeleton in breast cancer cells comparing NK-mediated cytotoxicity resistant and susceptible cell lines. (
  • Two parallel F-actin strands twist around each other in a helical formation, giving rise to microfilaments of the cytoskeleton. (
  • We discuss possible roles for Cax proteins in the regulation of the actin cytoskeleton. (
  • It has been proposed that the endurance of long-term potentiation (LTP) depends on structural changes entailing reorganization of the spine actin cytoskeleton. (
  • Actins are highly conserved proteins of the cytoskeleton and are involved in B lymphocyte activation. (
  • As cell migration is related to reorganization of the actin cytoskeleton, we also measured the cytoskeletal actin organization by staining F-actin with phalloidin in PC-3 cells and DU145 cells. (
  • Figure 1 Tying a knot in an actin filament. (
  • Dysfunctional actin-ATP binding may result in abnormal thin filament formation and impair muscle contraction, leading to muscle weakness and the other signs and symptoms of actin-accumulation myopathy. (
  • Bornemann A, Petersen MB, Schmalbruch H. Fatal congenital myopathy with actin filament deposits. (
  • The actin filament (F-actin) is composed of actin monomers (G-actin) polymerized head-to-tail to form two intertwining helical strands, resulting in a polar filament with a "barbed end" and a "pointed end" [ 10 ]. (
  • An early study of the Hsp25 (murine and avian isoform of Hsp27)-actin interaction concluded that Hsp25 was an actin filament barbed-end-capping protein based on limited evidence [ 26 ]. (
  • It is also unknown if Hsp27 interacts with the actin filament as a monomer, dimer, or higher multimer. (
  • Such a stoichiometry does not support the view that Hsp27 is simply an actin filament end-capping protein. (
  • Instead, we propose that Hsp27 binds along the side of the F-actin filament. (
  • It exists in two forms within eukaryotic cells: globular or G-actin and filament/filamentous or F-actin. (
  • Play media Initiation Consists of a number of different possible mechanisms that ultimately determine where and when actin filament elongation is to occur. (
  • This site provides a simple Java applet to build and study the structure of an actin filament. (
  • Talin contains three actin-filament- (F-actin-) binding domains located in the FERM domain (ABD1), the rod domain (ABD2), and the C-terminal domain (ABD3), respectively. (
  • Actin is a globular structural protein that polymerizes in a helical fashion to form an actin filament (or microfilament ). (
  • ATP-actin then binds the plus (+) end, and the ATP is subsequently hydrolyzed, which reduces the binding strength between neighboring units and generally destabilizes the filament. (
  • End-capping proteins such as CapZ prevent the addition or loss of monomers at the filament end where actin turnover is unfavorable, like in the muscle apparatus. (
  • Thymosin β4 is a protein that facilitates filament polymerization by G-actin-sequestering. (
  • Latrunculin has two forms (A and B) and inhibits the polymerization of actin by binding to lone monomers, this has the overall effect of promoting filament disassembly. (
  • An actin-bundling protein inhibits actin depolymerization even under conditions in which it cannot produce a gel, which suggests that bundling proteins may affect actin filament dynamics. (
  • Structures consisting of G-actin or other filament-forming monomers show a variety of morphologies with widely different properties in regard to pore size, degree of isotropy, and extent of cross-linking. (
  • Here, we introduce a Brownian dynamics (BD) simulation model in three dimensions in which actin monomers polymerize into a filament and become cross-linked by two types of cross-linking molecules that constitute either perpendicular or parallel cross-links. (
  • The viscoelastic property appears to be highly affected by characteristics of cross-linking molecules, average filament length, and concentration of actin monomers. (
  • A potential risk-conferring polymorphism (Ala934Val), identified in one DCM patient and one control individual, had a less pronounced effect on actin filament cross-linking. (
  • The polarity of an actin filament can be determined by decorating the microfilament with myosin "S1" fragments, creating barbed (+) and pointed (-) ends on the filament. (
  • Jasnin M., Crevenna A.H.: Quantitative analysis of filament branch orientation in Listeria actin comet tails. (
  • This third gathering of researchers devoted to the study of actin and actin-associated proteins was organized by Dr. James E. Estes, Albany Stratton V A Medical Center and Dr. Paul 1. (
  • Actin is a family of globular multi-functional proteins that form microfilaments. (
  • The evolutionary origin of actin can be traced to prokaryotic cells, which have equivalent proteins. (
  • A large number of illnesses and diseases are caused by mutations in alleles of the genes that regulate the production of actin or of its associated proteins. (
  • Realizing that Banga's coagulating myosin preparations contained actin as well, Szent-Györgyi called the mixture of both proteins actomyosin. (
  • Two other muscle proteins, tropomyosin and troponin, regulate the temporary fusion of actin and myosin that results in the contraction of muscle. (
  • Actin proteins are important for cell movement and the tensing of muscle fibers (muscle contraction). (
  • Actin is one of the most abundant proteins, that is present in almost all eukaryotic cells. (
  • However, the mechanism of the interaction between Hsp27 and actin is unclear and controversial and a binding study of the interaction between the two proteins in vitro has not been reported [ 3 ]. (
  • Since that study it has generally been assumed that Hsp25 and Hsp27 are actin barbed-end-capping proteins, although there has been little further support for this interaction model. (
  • The assembly of polymerized actin with motor proteins at DNA breaks in the nucleus supports the mobility and repair of DNA. (
  • Actin remains one of the most abundant proteins in all of Eukarya and is an enzyme (ATPase) that gradually hydrolyzes ATP. (
  • Over the course of the cycle, actin begins as a monomer, elongates into a polymer with the help of attached actin-binding-proteins, and disassembles back into a monomer so the remodeling cycle may commence again. (
  • In the mechanism that involves the uncapping of the barbed-end, diffusion-regulated actin polymerization of subunits bound to actin-monomer-sequestering proteins control initiation. (
  • Thymosin and Profilin both exist as actin-monomer-sequestering proteins that maintain the ability to limit spontaneous nucleation from occurring, thus halting the actin remodeling process and returning the cycle to its first step. (
  • Novel actin-related proteins Arp-T1 and Arp-T2 as components of the cytoskeletal calyx of the mammalian sperm head. (
  • Right, actin-binding proteins in focal complexes and focal adhesions. (
  • There is a large variety of different actin nucleators in human cells, such as formins, spire and Arp2/3-regulating proteins, and the list is likely to grow. (
  • Actin is one of the most abundant eukaryotic proteins. (
  • Actin is one of two major muscle proteins that play a crucial role in muscle cell contraction, the other protein being myosin . (
  • A relatively simple and ubiquitous protein, being found in most cells, Actin nonetheless demonstrates the extraordinary complexity-and one might say beauty-of creation, requiring a precise order of amino acids folded into a precise three-dimensional shape, and needing myosin, end capping proteins, ATP, and cell signaling mechanisms to function in muscle contraction. (
  • Actin is one of the most abundant proteins in many eukaryotic cells, with concentrations of over 100 μM. (
  • Like all proteins, actin is "born" at the ribosomes, the protein factories of the cell, which string together amino acids into a long chain. (
  • Unlike all previously studied proteins, actin cannot acquire its fold in absence of the chaperonin TRiC. (
  • Actin has many more protein interaction partners than the bacterial cytoskeletal proteins, but it has lost the ability to fold independently. (
  • Recent studies have greatly expanded our understanding of actin-bundling proteins. (
  • A new group of actin-bundling proteins, the fascins, has been recognized. (
  • Northern blot analysis showed the expression of the beta-actin gene was only approximately 20% lower in 4-ABP-treated PC cells than in untreated controls, indicating the cellular change in actin was attributed to a shift between F- and G-actin proteins rather than to net actin synthesis. (
  • Actins are highly conserved proteins that are involved in various types of cell motility and are ubiquitously expressed in all eukaryotic cells. (
  • Actin is highly conserved (the amino-acid sequence of actin from Acanthamoeba (a small soil amoeba) is 95% identical to vertebrate isoforms of actin), and it forms a huge variety of structure in cells in concert with many different actin binding proteins (there are between 60 and 100 different actin binding proteins). (
  • The ADF/cofilin group of actin-binding proteins are particularly complex in their relationship with actin, and can either stimulate polymerisation or depolymerisation, depending on the conditions (particularly pH). (
  • Actin and myosin are the two major cytoskeletal proteins implicated in cell motility. (
  • Actin is one of the most conserved eukaryotic proteins with at least six isoforms. (
  • The NH 2 -terminal region of actin appears to be a major antigenic region and may be involved in the interaction of actin with other proteins such as myosin. (
  • When a muscle is activated, it is the proteins myosin and actin that go to work. (
  • Actin polarity is thought to be crucial for the inheritance of various organelles =-=(22)-=- and may be important for the asymmetric distribution of damaged proteins, as well. (
  • In this study, we investigated the interaction of each domain with F-actin, recombinant Tetrahymena CaM, and eEF1A itself in vitro, using three glutathione-S-transferase-domain fusion proteins (GST-dm1, -2, and -3). (
  • Here we have studied the dynamic activity of proteins involved in regulating actin polymerization in live T cells after activation. (
  • Besides, we offer the CellGlow™ reagents to label actin and tubulin in live cells with fluorescent proteins. (
  • The protein actin is one of the most highly conserved throughout evolution because it interacts with a large number of other proteins, with 80.2% sequence conservation at the gene level between Homo sapiens and Saccharomyces cerevisiae (a species of yeast), and 95% conservation of the primary structure of the protein product. (
  • Beta-actin is an isform of actin proteins. (
  • Actins are highly conserved proteins that are involved in cell motility, structure, and integrity. (
  • It is also known as BRWS1 or PS1TP5BP1.This gene encodes one of six different actin proteins. (
  • EV71 is endemic in the Asia-Pacific region and causes occasional epidemics.Significant differences have been found in the beta-actin variants between the EV71-susceptible RD cells and EV71-resistant RD cells, suggesting that beta-actin, in association with other proteins such as annexin 2 is required in vesicular transport of EV71. (
  • Despite its complexity, actin remodeling may result in complete cytoskeletal reorganization in under a minute. (
  • Arp-T1 is an actin-related protein (Arp) that serves as a component of the cytoskeletal calyx of the mammalian sperm head [ PMID: 12243744 ]. (
  • Quantitative changes in cytoskeletal and nuclear actins during cellular transformation. (
  • In response to cytoskeletal reorganizing signals during processes such as cytokinesis, endocytosis, or stress, cofilin promotes fragmentation and depolymerization of F-actin, resulting in an increase in the monomeric globular form, G-actin (3). (
  • Actin plays a variety of roles in cytoskeletal structural support, cell motility, cellular junctions, muscle contraction, and cellular signaling. (
  • This actin is a major constituent of the contractile apparatus and one of the two nonmuscle cytoskeletal actins. (
  • Application of drugs that attenuate either microtubule or F-actin dynamics also inhibits polymerization of the other cytoskeletal element. (
  • Following up on the discovery of Ilona Banga & Szent-Györgyi in 1941 that the coagulation only occurs in some mysosin extractions and was reversed upon the addition of ATP, Straub identified and purified actin from those myosin preparations that did coagulate. (
  • Since Straub's protein was necessary to activate the coagulation of myosin, it was dubbed actin. (
  • When a signal for muscle contraction is sent along a nerve to a muscle cell , actin and myosin are activated. (
  • Additionally, the respective ends of the actin microfilament are often specified by their appearance under transmission electron microscopy during a technique known as "decoration", where the addition of myosin results in distinctive actin-myosin binding at each terminus. (
  • One of the protein components found in muscle, existing as F-actin or G-actin, into which actomyosin can be split and which acts with myosin in muscle contraction. (
  • Actin and the protein myosin together make up the contractile units (called sarcomeres ) of skeletal muscle fibers. (
  • As constituents of many cell types, actin and myosin are involved in a myriad of cellular process including locomotion, secretion, cytoplasmic streaming, phagocytosis, and cytokinesis. (
  • Protocols and information relating to actin and myosin. (
  • Myosin molecules take hold of actin molecules and pull, like rope pulling, in a process that gets energy from the use of the cellular fuel ATP. (
  • Myosin has two heads called subfragment-1 (S-1) and binds to F-actin in the absence of ATP. (
  • Functional nonequivalence of Drosophila actin isoforms. (
  • We show that different Drosophila actin isoforms are not interchangeable. (
  • In order to establish the consequences of multiple amino acid replacements, we substituted portions of the Drosophila Act88F actin gene with corresponding regions of genes encoding other isoforms. (
  • While all actin isoforms are highly homologous, cytoplasmic β- and γ-actin protein sequences differ by only four biochemically similar amino acids (2). (
  • These actin isoforms regulate the contractile potential of muscle cells (1). (
  • Actin isoforms show greater than 90% overall sequence homology, but only 50-60% homology in their 18 NH2-terminal residues. (
  • Although most yeasts have only a single actin gene, higher eukaryotes , in general, express several isoforms of actin encoded by a family of related genes. (
  • Mammals have at least six actin isoforms coded by separate genes, [1] which are divided into three classes (alpha, beta and gamma) according to their isoelectric point . (
  • In general, alpha actins are found in muscle (α-skeletal, α-aortic smooth, α-cardiac, and γ2-enteric smooth), whereas beta and gamma isoforms are prominent in non-muscle cells (β- and γ1-cytoplasmic). (
  • There are six different but highly conserved actin isoforms in vertebrates. (
  • Four of these isoforms are expressed primarily in striated and smooth muscle cells, whereas beta-actin and gamma-actin isoforms are ubiquitously expressed. (
  • This conference focused on the fundamental properties and cellular functions of actin and actin- based microfilament systems. (
  • Neurobiology of Actin: From Neurulation to Synaptic Function opens with a chapter that presents the fundamental concepts required to appreciate the details of the molecular machinery that regulates actin in a cellular context, setting the stage for the first part of the book which reviews the neurobiology of actin at the cellular level. (
  • It can be present as either a free monomer called G-actin (globular) or as part of a linear polymer microfilament called F-actin (filamentous), both of which are essential for such important cellular functions as the mobility and contraction of cells during cell division. (
  • Actin participates in many important cellular processes, including muscle contraction, cell motility, cell division and cytokinesis, vesicle and organelle movement, cell signaling, and the establishment and maintenance of cell junctions and cell shape. (
  • Many of these processes are mediated by extensive and intimate interactions of actin with cellular membranes. (
  • Actin therefore contributes to processes such as the intracellular transport of vesicles and organelles as well as muscular contraction and cellular migration. (
  • Actin remodeling is the biochemical process that allows for the dynamic alterations of cellular organization. (
  • The actin and microtubule (MT) cytoskeletons are key structural components that allow and coordinate rapid and sometimes drastic changes in cellular morphology, such as polarization, migration and cytokinesis. (
  • however, there is a growing body of work indicating that the cooperative functioning of actin and microtubules is a central element for many cellular key processes, including cell division, cell migration, and adhesion. (
  • Figure 2: Different geometrical and mechanical actin networks, to account for the diverse cellular architectures. (
  • The dynamic processes that occur during the growth of actin, via polymerization, and the breakdown of actin both play significant roles in cellular mechanisms like migration and adhesion. (
  • Researchers from the department "Cellular Biochemistry" of MPIB director F.-Ulrich Hartl have now revealed the unique non-folding properties of the universal protein actin. (
  • Actin, a highly conserved protein comprising cell stress fibers and other cellular structures, is found in both the cytoplasm and nucleus of cells and responds to both epigenetic signals and altered gene expression occurring during tumorigenesis. (
  • Molecules recruited to the TCR regulate actin polymerization and this process drives plasma membrane movement and cellular spreading. (
  • Thus, actin participates in many important cellular functions, including muscle contraction , cell motility , cell division and cytokinesis , vesicle and organelle movement, cell signaling , and the establishment and maintenance of cell junctions and cell shape. (
  • We aim to understand how the native molecular architectures of actin-based cellular processes give rise to force generation and rigidity-sensing. (
  • We use cryo-electron tomography, and develop methodologies allowing for quantitative analysis of cellular actin networks architectures. (
  • Actin is a globular, roughly 42-kDa protein found in all eukaryotic cells (except for nematode sperm) where it may be present at concentrations of over 100 μM. (
  • During the remodeling process, actin monomers polymerize in response to signaling cascades that stem from environmental cues. (
  • Simultaneously, older G-actin monomers "fall off" of the pointed end of the microfilament. (
  • At the "pointed end" of the F-actin polymer, actin monomers are bound to ADP, which dissociates more readily and rapidly than ATP-bound actin, which is found at the "barbed end" of the polymer. (
  • At this point, both termini accept the addition of new monomers (although primarily at the "barbed end") and the actin microfilament lengthens. (
  • The individual subunits of actin (monomers) are known as globular actin, or for short G-actin. (
  • The process of actin polymerization starts with the association of three G-actin monomers into a trimer. (
  • Cofilin encourages depolymerization by promoting dissociation of actin monomers from the actin chain. (
  • Profilin assists polymerization by regulating the creation of ATP-actin monomers to add to the growing actin chain. (
  • Spires are organization factors that promote polymerization by bringing actin monomers together to form a prenucleation scaffold. (
  • Its polymerizing enzyme is not yet known, but the group found that it required calcium and especially high concentrations of actin monomers. (
  • Actin, a protein found in every eukaryotic cell, exists as both monomers and polymers and can be found in many different tertiary forms. (
  • Actin can be labeled with a fluorophore very easily when the monomers form a certain type of microfilament, referred to as F-actin. (
  • ACTA1 gene mutations that cause actin-accumulation myopathy may affect the way the skeletal α-actin protein binds to ATP. (
  • The protein cofilin binds to ADP-actin units and promotes their dissociation from the minus end and prevents their reassembly. (
  • Actin Staining in Fixed Yeast Cells Protocol Phalloidin binds specifically to F-actin, and fluorescent-tagged phalloidin stains the actin skeleton in cells in a manner that is very close to the staining pattern seen using anti-actin antibody. (
  • Fluorescence emission intensity from a culture of bovine pulmonary artery endothelial cells stained with BODIPY FL phallacidin, which binds to the intracellular filamentous actin network. (
  • Rhodamine-phalloidin, which selectively binds to polymerized actin, was detected in perikarya and proximal dendrites of CA1 pyramidal cells that received low-frequency afferent activity but was essentially absent in spines and fine dendritic processes. (
  • Phalloidin, a molecule isolated from death cap mushrooms, binds F-actin microfilaments very tightly and with high specificity and-unlike many primary antibodies against actin-does not bind other forms of actin. (
  • vc]) covalently binds to G-actin and F-actin , and causes actin depolymerization, which leads to cell rounding (Kudryashov et al. (
  • Western blot analysis of extracts from HeLa, L929, C6 and COS cells, using Pan-Actin Antibody. (
  • Immunohistochemical analysis of paraffin-embedded human colon (smooth muscle), using Pan-Actin Antibody. (
  • Mouse IgG1, kappa light chain, monoclonal antibody raised against chicken gizzard actin. (
  • The monoclonal actin (clone B4) antibody is a mouse IgG1, kappa light chain antibody. (
  • This antibody can be used to detect the other smooth muscle actin (alpha-skeletal, alpha-cardiac and alpha-vascular) found in vertebrates. (
  • Hsp27 has been implicated in numerous physiological and pathological processes that involve its interaction with actin and its control of actin dynamics [ 11 - 25 ]. (
  • and in turn, how actin structures within the cell are affected by varying MT dynamics. (
  • Force transmission to the extracellular matrix depends on several parameters including the regulation of actin dynamics in adhesion structures, the contractility of stress fibers, and the mechanosensitive response of adhesion structures. (
  • The migratory cycle is a complex process in which actin dynamics play a central role at every step. (
  • Local release of PIP2 controls actin dynamics in specific subcellular regions and plays a critical role in regulating actin-based cell motility and morphogenesis. (
  • Coordinating neuronal actin-microtubule dynamics. (
  • Here, we summarise our current understanding of the structure and dynamics of actin and microtubules in isolation, before reviewing both the mechanisms and the molecular players involved in mediating actin-microtubule crosstalk in neurons. (
  • Importantly, inhibition of microtubule or F-actin dynamics prevents axon branching but not axon elongation. (
  • Focal adhesion kinase is a regulator of F-actin dynamics: New insights from studies in the testis," Spermatogenesis 3(3): e25385. (
  • Actin networks in cell migration and organization of nascent adhesions and focal adhesions. (
  • One of four intragenic complementing groups of temperature-sensitive yeast calmodulin mutations, cmd1A , results in a characteristic functional defect in actin organization. (
  • Interestingly, all the mutations themselves affect actin organization. (
  • Each group has a characteristic functional defect in actin organization ( cmd1A ), calmodulin localization ( cmd1B ), nuclear division ( cmd1C ), or bud emergence ( cmd1D ). (
  • Enlargement requires actin polymerization, prompting the authors to examine spine actin organization in brain slices before and after synaptic stimulation. (
  • Jasnin M., Ecke M., Baumeister W., Gerisch G.: Actin organization in cells responding to a perforated surface, revealed by live imaging and cryo-electron tomography. (
  • Actin assembles into short polymer microfilaments, these are thought to contribute to parasite gliding motility. (
  • Actin is a globular protein that can polymerise to form microfilaments . (
  • Finally, to test whether the anti-actin ELISA used was specific for F-actin , we assayed for IgG anti- F-actin in 18 sera from patients with type 1 AH, positive by IF for IgG anti- F-actin on HEP-2 cells (titer range, 1:160 -1:1280), and 30 negative sera from healthy controls. (
  • It exists in two forms: G-actin (monomeric globular actin) and F-actin (polymeric fibrous actin), the form involved in muscle contraction. (
  • Globular actin is the monomeric form of the protein while the filamentous actin is a linear polymer of globular subunits. (
  • Jasplakinolide induces the polymerization of actin and stabilizes actins monomeric form. (
  • The official symbol of beta-actin gene is ACTB (provided by HGNC). (
  • Beta-actin gene and regulatory elements, preparation and use. (
  • Here we highlight recent findings on the molecular mechanisms by which actin assembly is regulated in adhesion structures and the molecular basis of the mechanosensitivity of focal adhesions. (
  • 1) The mechanism by which actin assembly is initiated in nascent adhesions, (2) the mechanosensitive maturation of FAs, (3) the molecular mechanisms underlying the formation of stress fibers, and (4) the regulation of actin assembly in focal adhesions. (
  • Due to the critical role that actin plays in these processes, cancer and cardiovascular research is currently focusing on understanding the molecular processes that occur during actin reorganization. (
  • But actin is different because it absolutely requires the molecular folding help of TRiC. (
  • It seems like this molecular trade-off made the versatility of actin possible", comments Balchin. (
  • Instead, their test tube was filled with some "contaminant": A high molecular weight polymer they would soon identify as the first actin-binding protein, later called filamin A. (
  • The team next analyzed the effects of the actin rearrangement in cancer cells at the molecular level. (
  • The molecular weight (MW) of beta-actin is approximately 42 kD. (
  • This article explores key molecules for research into actin polymerization . (
  • When tropomyosin molecules are added to the solution of F-actin, they bind to F-actin and settle in the grooves of F-actin helix forming tropomyosin strands (Fig. ld). (
  • In order to address some of these issues we have investigated the interaction between Hsp27 and actin, in vitro , using fluorescence probes attached to Hsp27. (
  • To determine whether nuclear actin is also altered and how nuclear and cytoplasmic actin alterations are interrelated in transformation, an in vitro model of carcinogen-induced transformation consisting of 2 human uroepithelial cell lines immortalized by infection with SV-40 was studied. (
  • Altering the methionine 44 residue makes actin resistant to Mical-mediated disassembly in vitro and in vivo in Drosophila . (
  • Cleavage of actin under apoptotic conditions has been observed in vitro and in cardiac and skeletal muscle, as shown in research studies (5-7). (
  • In vitro, cortactin promoted the formation and stabilization of actin branches. (
  • We demonstrate here that in vitro capacitation of bull, ram, mouse, and human sperm was accompanied by a time-dependent increase in actin polymerization. (
  • Inhibition of F-actin formation by cytochalasin D blocked sperm capacitation and reduced the in vitro fertilization rate of metaphase II-arrested mouse eggs. (
  • The filamentous polymer composed of individual G-actin subunits is a microfilament and is called F-actin. (
  • In addition, ATP-actin units bound to profilin will dissociate from cofilin and are then free to polymerize. (
  • The fluorescence of acrylodan attached to Hsp27 increased 4-5-fold upon interaction with F-actin. (
  • Upon interaction with F-actin the pyrene-Hsp27 excimer fluorescence was largely lost, suggesting that Hsp27 interacts with F-actin as a monomer, consistent with the acrylodan-Hsp27 results. (
  • CytoPainter F-actin Staining Kit - Blue Fluorescence (ab112124). (
  • Fluorescence emission intensity from a culture of human bone osteosarcoma ( U2OS line) epithelial cells that were transfected with a pEYFP-Actin plasmid subcellular localization vector. (
  • d) Fluorescence microscopy observed the increased H9c2 cells surface area of F-actin staining in PA group, which was suppressed by Nec- 1 (10 nM), according to the semiquantitative results by ImageJ software, n = 3. (
  • The second section of the book then discusses the functions of actin in the context of neurobiological issues ranging from early development to synaptic function and disease states of the nervous system. (
  • One explanation for this is that the many functions of actin require a large degree of biochemical and structural plasticity and heterogeneity. (
  • Polymerization of actin also increases the mobility of DNA breaks that will be repaired by HR and the ability of a subset of DNA breaks to form clusters in the nucleus. (
  • These results indicate that near-threshold conditions for inducing stable potentiation cause the rapid polymerization of actin in mature spines and suggest that the effect is both sufficiently discrete to satisfy the synapse-specificity rule of LTP as well as rapid enough to participate in the initial stages of LTP consolidation. (
  • Interestingly, the toxin phalloidin is used in conjunction with fluorescent dyes to visualize the actin in cells in microscopy . (
  • We offer a selection of phalloidin conjugates to label actin in fixed and permeabilized cells. (
  • The present study used a new technique involving intracellular and extracellular application of rhodamine-phalloidin to conventional hippocampal slices to test whether induction of LTP by naturalistic patterns of afferent activity selectively increases actin polymerization in juvenile to young adult spines. (
  • Actin staining with fluorescent phalloidin conjugates can be easily added to an immunolabeling protocol. (
  • After fixing, permeabilizing, and blocking, BPAE cells were labeled with ActinRed™ reagent (TRITC-conjugated phalloidin that labels F-actin), and nuclei were labeled with NucBlue™ Fixed reagent (a form of DAPI). (
  • If you have trouble visualizing F-actin using a phalloidin-conjugated fluorophore, try optimizing your sample fixation time. (
  • 25% bovine serum albumin for 30 min, and stained with phalloidin and DAPI solution to visualize F-actin and nuclei, respectively (Life Technology, Seoul, Korea). (
  • Invasive cell migration requires the formation of various structures, such as invadopodia and pseudopodia, which require actin assembly that is regulated by specialized actin nucleation factors. (
  • Studies of the mechanisms of various actin nucleation factors that are involved in cancer cell function may ultimately provide new treatments for invasive and metastatic disease. (
  • Formins are a group of nucleation and elongation factors that promote the formation of linear actin chains. (
  • The ARP 2/3 complexes behaves as a nucleation site for actin by mimicking the structure of an actin trimer. (
  • Vesicles organize their own actin tracks by recruiting the actin nucleation factors Spire1, Spire2 and Formin-2, which assemble an extensive actin network from the vesicles' surfaces. (
  • Gallego, M.D., Santamaria, M., Pena, J. & Molina, I.J. Defective actin reorganization and polymerization of Wiskott-Aldrich T cells in response to CD3-mediated stimulation. (
  • Reports that actin also has functions in the cell nucleus remain controversial 1 , 2 , partly because of the challenges of performing experiments that exclusively perturb the nuclear actin pool without also perturbing actin in the cytoplasm. (
  • In the cytosol (fluid component of cytoplasm), actin is predominantly bound to adenosine triphosphate , or ATP. (
  • After incubation with 4-ABP, F-actin decreased and G-actin increased in both cytoplasm and nuclei of PC cells and cytoplasmic F-actin fibers were lost, but only cytoplasmic actin was altered in the BC cells. (
  • Being organized in a dynamic vesicle-actin network allows vesicles to move in a local random manner and a global directed manner at the same time: they can reach any position in the cytoplasm, but also move directionally to the cell surface as a collective. (
  • The actin patch is a highly dynamic actin structure in fungi required primarily for endocytosis but possibly also coupled to exocytosis. (
  • Nuclear actin polymerizes to preserve genome stability. (
  • Nonmuscle β- and γ-actin, also known as cytoplasmic actin, are ubiquitously expressed, controlling cell structure and motility (1). (
  • Complementary DNA sequence of a human cytoplasmic actin. (
  • The assembly of filamentous actin arises as a result of weak, noncovalent interactions between G-actin and appears in the arrangement of a two-stranded asymmetrical helical polymer. (
  • showing that ATP hydrolysis and release of a phosphate group results in one segment of actin switching from a strand to a helical conformation. (
  • F-actin is a two-stranded helical polymer. (
  • Actin plasticity is probably required to accommodate its multiple interactions and functions. (
  • leton either directly or indirectly through its interactions with components of the actin/septin machinery (Fig. 4A). (
  • Although actin is known to play an important role in regulating the distribution of microtubules, the exact nature of F-actin-microtubule interactions in the growth cone is not well understood ( Suter and Forscher, 2000 ) and has not been well characterized in motile cells ( Waterman-Storer and Salmon, 1999 ). (
  • To anchor the protrusion, the cell front interacts with the extracellular matrix (ECM) by forming nascent adhesions (or focal complexes) that are connected to the intracellular lamellipodial actin network. (
  • In this process, G-actin subunits primarily add to the "barbed end" of the filamentous polymer. (
  • Actin occurs in two forms, as a monomer and as a polymer. (
  • Actin exists mainly as a fibrous polymer, F-actin. (
  • Mutations and polymorphisms of the skeletal muscle alpha-actin gene (ACTA1). (
  • Skeletal muscle α-actin diseases (actinopathies): pathology and mechanisms. (
  • A number of disease-causing mutations in the human ACTA1 gene that encodes skeletal muscle actin affect residues in the most dynamic structural elements of the protein. (
  • Immunoblotting Rat skeletal muscle and HeLa total cell extract were separated on SDS-PAGE and probed with monoclonal AIA to Actin N-Terminal (RB) (Cat. (
  • Left, scheme of a migrating cell displaying characteristic actin structures: lamellipodial and filopodial actin networks and the three classes of stress fibers (transverse arcs, dorsal stress fibers, ventral stress fibers). (
  • Royle and colleagues first observed that in HeLa cells, cortactin, a protein that activates actin polymerization, was present in clathrin structures during interphase but was greatly reduced during mitosis. (
  • These structures provide architectural specificities for different regions of the cell, and can also organize into more complex actin-based machineries. (
  • and F-actin (polymeric fibrous actin), the form involved in muscle contraction. (
  • Mutations in the different genes that regulate actin production in humans can cause muscular diseases, variations in the size and function of the heart as well as deafness. (
  • Ca 2 /calmodulin (CaM) causes reversion of the eEF1A dimer to the monomer, which loosens F-actin bundling, and then Ca 2 /CaM/eEF1A monomer complexes dissociate from F-actin. (
  • It polymerizes to form filamentous actin (F-actin), which plays a key role in regulating cell shape, polarity, and force generation. (
  • Until now, there have been no tools to visualize actin or the actin-binding protein fimbrin in live cells of a filamentous fungus. (
  • G-actin subunits assemble into long filamentous polymers called F-actin. (
  • The work presented herein focuses on the mechanical response of cross-linked actin networks. (
  • In Paper B, a finite element framework was used to assess the influence of numerous geometrical and material parameters on the response of cross-linked actin networks. (
  • Finally, a micromechanically motivated constitutive model in a continuum framework was presented, capturing some essential characteristic features of cross-linked actin networks. (
  • Figure 1: TIRF images of dynamic microtubules in a polymerizing actin network. (
  • Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. (
  • R.-J. Hung, C. W. Pak, J. R. Terman, Direct redox regulation of F-actin assembly and disassembly by Mical. (
  • RESTORATION HARDWARE: During interphase, mammalian cells have low membrane tension, and clathrin-mediated endocytosis (CME) proceeds normally with no special need for actin (1). (
  • An unmet actin requirement explains the mitotic inhibition of clathrin-mediated endocytosis," eLife , 3:e00829, 2014. (
  • This led Royle's team to investigate whether inactive actin was prohibiting endocytosis from occurring. (
  • The researchers showed that, during mitosis, much of the actin is engaged with the cell's rigid cortex, which causes the cells to become round during mitosis, and none is available to help out with endocytosis. (
  • This finding nixed the idea that increased membrane tension alone is responsible for the endocytosis shutdown, and instead led the team to propose that actin availability determines whether endocytosis proceeds. (
  • It seems that whether actin is required for endocytosis really depends on how much work the endocytic machinery has to do to create a vesicle," says Royle. (
  • Still, Traub suspects that actin unavailability is not the only regulatory mechanism controlling endocytosis. (
  • Our data support a novel apical recycling model which indicates a critical role for actin patch-mediated endocytosis to maintain polarized growth at the apex. (
  • Actin-propelled invasive membrane protrusions promote fusogenic protein engagement during cell-cell fusion. (
  • Actin is implicated in chemotaxis , phagocytosis , pinocytosis , membrane ruffling , and pretty much anything that requires the shape of a cell to change. (
  • Actin assembly drives the extension of flat membrane protrusions called lamellipodia and finger-like protrusions called filopodia to push the membrane. (
  • During mitosis, membrane tension is high, the actin (purple) is sequestered at the cell cortex, and CME can't proceed because actin is required to help stretch the clathrin-coated pits to form full vesicles (2). (
  • Royle's team is now addressing how the endocytic machinery is able to sense high membrane tension and recruit actin within cells of tissues undergoing physical stretching or in polarized epithelial cells, which have different tensions at their basolateral and apical membranes. (
  • The overall outward-directed movement of the vesicle-actin network is driven by recruitment of vesicles to the plasma membrane in the periphery of the oocyte. (
  • Heinrich D., Ecke M., Jasnin M., Engel U., Gerisch G.: Reversible membrane pearling in live cells upon destruction of the actin cortex. (
  • Actin , protein that is an important contributor to the contractile property of muscle and other cells . (
  • 4 report that, in human cells, polymerized actin promotes the processing (resection) of broken DNA ends in chromatin (the compartments involved were not determined) and facilitates a DNA-repair pathway called homologous recombination (HR, not shown), although the underlying mechanism is unclear. (
  • Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle contractions. (
  • Cytoplasmic and nuclear F- and G-actin were determined by QFIA on individual cells using fluorochrome-labeled phallicidin and DNase, I, respectively. (
  • Before exposure to 4-ABP, the PC cells had lower cytoplasmic F-actin content, higher cytoplasmic G-actin content, but similar levels of nuclear G- and F-actin in comparison to the BC cells. (
  • A dynamic polymeric actin structure inside the nucleus is part of the serum response in mammalian tissue culture cells. (
  • Immunoblotting Chicken fi broblast cells extract was separated on SDS-PAGE and probed with Monoclonal PA to Actin (Cat. (
  • Actin does not react with the α-actin of non-muscle (endothelial cells) sources (1). (
  • In cells, live imaging showed that PI(3,5)P 2 promoted turnover of endosomal actin if cortactin was present. (
  • In contrast to cells transfected in culture, where the level of actin-GFP expression in neurons varies considerably, transgenic mice. (
  • T cell receptor (TCR) engagement leads to actin polymerization at the site of T cell contact with antigen-presenting cells. (
  • When using high-throughput imaging flow cytometry we observed that actin massively concentrates at the immunological synapse in tumor cells resistant to NK cytotoxicity, indicating a causal link between this actin response and resistance,' states Dr. Al Absi who conducted the major part of the experimental work. (
  • This abolished the actin response and made previously resistant cancer cells remarkably more susceptible to NK cell attack. (
  • Thus the actin response is linked to the protection of cancer cells against the attack of NK cells. (
  • On cells with an actin response, a significant increase in immune-inhibitory ligands such as HLA-A, -B, -C and the immune checkpoint protein PD-L1 was found at the contact site with NK cells. (
  • The researchers thus concluded that the actin response protects cancer cells from lysis by limiting the accumulation of granzyme B. They are currently evaluating the hypothesis that the actin response actually drives the local recruitment of immune-inhibitory ligands to alter the cytotoxic function of immune cells. (
  • Finally, to validate their results, Dr. Al Absi and co-workers also monitored the actin response using primary NK cells isolated from donors to exclude that the phenomenon is solely observable with the NK cell line initially used for the study. (
  • The plasmid -derived gene ParM encodes an actin-like protein whose polymerised form is dynamically unstable , and appears to partition the plasmid DNA into the daughter cells during cell division by a mechanism analogous to that employed by microtubules in eukaryotic mitosis . (
  • Induction of the acrosome reaction in capacitated cells initiated fast F-actin breakdown. (
  • Incubation of sperm in media lacking BSA or methyl-β-cyclodextrin, Ca 2 , or NaHCO 3 , components that are all required for capacitation, prevented actin polymerization as well as capacitation, as assessed by the ability of the cells to undergo the acrosome reaction. (
  • Beta-actin, also known as a "housekeeping" protein, is usually used as a loading control , for among others, the integrity of cells, protein degradation, in PCR and Western blotting. (
  • Actin plays important roles in many biological processes, such as establishing cell polarization, accommodating protruding and retracting activities of motile cells, maintaining the physical integrity of the cell, and sensing environmental forces. (
  • Cryo-electron tomography workflow (A-D) and actin architecture (E-G) in a thin protrusion assembled by Dictyostelium cells in response to a hole. (
  • Specifically, shrunken cells and F-actin accumulation were observed after nicotine treatment. (
  • Prior to neural tube closure, F-actin is accumulated at the medial plane of the epidermal cells adjacent to the neural plate. (
  • While other researchers were consumed with showing a direct role for actin in the formation of endocytic vesicles, this study shows that if actin is not available, vesicle budding cannot occur," says Linton Traub, a cell biologist at the University of Pittsburgh who was not involved in the study. (