Protein Transport: 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.Biological Transport: The movement of materials (including biochemical substances and drugs) through a biological system at the cellular level. The transport can be across cell membranes and epithelial layers. It also can occur within intracellular compartments and extracellular compartments.Golgi Apparatus: A stack of flattened vesicles that functions in posttranslational processing and sorting of proteins, receiving them from the rough ENDOPLASMIC RETICULUM and directing them to secretory vesicles, LYSOSOMES, or the CELL MEMBRANE. The movement of proteins takes place by transfer vesicles that bud off from the rough endoplasmic reticulum or Golgi apparatus and fuse with the Golgi, lysosomes or cell membrane. (From Glick, Glossary of Biochemistry and Molecular Biology, 1990)Biological Transport, Active: The movement of materials across cell membranes and epithelial layers against an electrochemical gradient, requiring the expenditure of metabolic energy.Membrane Transport Proteins: Membrane proteins whose primary function is to facilitate the transport of molecules across a biological membrane. Included in this broad category are proteins involved in active transport (BIOLOGICAL TRANSPORT, ACTIVE), facilitated transport and ION CHANNELS.Brefeldin A: A fungal metabolite which is a macrocyclic lactone exhibiting a wide range of antibiotic activity.Endoplasmic Reticulum: A system of cisternae in the CYTOPLASM of many cells. In places the endoplasmic reticulum is continuous with the plasma membrane (CELL MEMBRANE) or outer membrane of the nuclear envelope. If the outer surfaces of the endoplasmic reticulum membranes are coated with ribosomes, the endoplasmic reticulum is said to be rough-surfaced (ENDOPLASMIC RETICULUM, ROUGH); otherwise it is said to be smooth-surfaced (ENDOPLASMIC RETICULUM, SMOOTH). (King & Stansfield, A Dictionary of Genetics, 4th ed)Vesicular Transport Proteins: A broad category of proteins involved in the formation, transport and dissolution of TRANSPORT VESICLES. They play a role in the intracellular transport of molecules contained within membrane vesicles. Vesicular transport proteins are distinguished from MEMBRANE TRANSPORT PROTEINS, which move molecules across membranes, by the mode in which the molecules are transported.Membrane Proteins: 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.Intracellular Membranes: Thin structures that encapsulate subcellular structures or ORGANELLES in EUKARYOTIC CELLS. They include a variety of membranes associated with the CELL NUCLEUS; the MITOCHONDRIA; the GOLGI APPARATUS; the ENDOPLASMIC RETICULUM; LYSOSOMES; PLASTIDS; and VACUOLES.Carrier Proteins: Transport proteins that carry specific substances in the blood or across cell membranes.Axonal Transport: The directed transport of ORGANELLES and molecules along nerve cell AXONS. Transport can be anterograde (from the cell body) or retrograde (toward the cell body). (Alberts et al., Molecular Biology of the Cell, 3d ed, pG3)Cathepsin A: A carboxypeptidase that catalyzes the release of a C-terminal amino acid with a broad specificity. It also plays a role in the LYSOSOMES by protecting BETA-GALACTOSIDASE and NEURAMINIDASE from degradation. It was formerly classified as EC and EC Vesicles: Vesicles that are involved in shuttling cargo from the interior of the cell to the cell surface, from the cell surface to the interior, across the cell or around the cell to various locations.Molecular Sequence Data: 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.Coatomer Protein: A 700-kDa cytosolic protein complex consisting of seven equimolar subunits (alpha, beta, beta', gamma, delta, epsilon and zeta). COATOMER PROTEIN and ADP-RIBOSYLATION FACTOR 1 are principle components of COAT PROTEIN COMPLEX I and are involved in vesicle transport between the ENDOPLASMIC RETICULUM and the GOLGI APPARATUS.Amino Acid Sequence: 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.Ion Transport: The movement of ions across energy-transducing cell membranes. Transport can be active, passive or facilitated. Ions may travel by themselves (uniport), or as a group of two or more ions in the same (symport) or opposite (antiport) directions.Saccharomyces cerevisiae Proteins: 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.Saccharomyces cerevisiae: 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.Vacuoles: Any spaces or cavities within a cell. They may function in digestion, storage, secretion, or excretion.Cell Membrane: The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells.Fungal Proteins: Proteins found in any species of fungus.Peas: A variable annual leguminous vine (Pisum sativum) that is cultivated for its rounded smooth or wrinkled edible protein-rich seeds, the seed of the pea, and the immature pods with their included seeds. (From Webster's New Collegiate Dictionary, 1973)Cyclopentanes: A group of alicyclic hydrocarbons with the general formula R-C5H9.trans-Golgi Network: A network of membrane compartments, located at the cytoplasmic side of the GOLGI APPARATUS, where proteins and lipids are sorted for transport to various locations in the cell or cell membrane.Protein Sorting Signals: Amino acid sequences found in transported proteins that selectively guide the distribution of the proteins to specific cellular compartments.Kinetics: The rate dynamics in chemical or physical systems.rab2 GTP-Binding Protein: A protein involved in transport between the ENDOPLASMIC RETICULUM and the GOLGI APPARATUS. This enzyme was formerly listed as EC 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.rab GTP-Binding Proteins: A large family of MONOMERIC GTP-BINDING PROTEINS that play a key role in cellular secretory and endocytic pathways. EC 3.6.1.-.Cell Compartmentation: A partitioning within cells due to the selectively permeable membranes which enclose each of the separate parts, e.g., mitochondria, lysosomes, etc.Models, Biological: 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.COP-Coated Vesicles: TRANSPORT VESICLES formed when cell-membrane coated pits (COATED PITS, CELL-MEMBRANE) invaginate and pinch off. The outer surface of these vesicles is covered with a lattice-like network of COP (coat protein complex) proteins, either COPI or COPII. COPI coated vesicles transport backwards from the cisternae of the GOLGI APPARATUS to the rough endoplasmic reticulum (ENDOPLASMIC RETICULUM, ROUGH), while COPII coated vesicles transport forward from the rough endoplasmic reticulum to the Golgi apparatus.Chloroplast Proteins: Proteins encoded by the CHLOROPLAST GENOME or proteins encoded by the nuclear genome that are imported to and resident in the CHOROPLASTS.Monosaccharide Transport Proteins: A large group of membrane transport proteins that shuttle MONOSACCHARIDES across CELL MEMBRANES.Thylakoids: Membranous cisternae of the CHLOROPLAST containing photosynthetic pigments, reaction centers, and the electron-transport chain. Each thylakoid consists of a flattened sac of membrane enclosing a narrow intra-thylakoid space (Lackie and Dow, Dictionary of Cell Biology, 2nd ed). Individual thylakoids are interconnected and tend to stack to form aggregates called grana. They are found in cyanobacteria and all plants.beta-Fructofuranosidase: A glycoside hydrolase found primarily in PLANTS and YEASTS. It has specificity for beta-D-fructofuranosides such as SUCROSE.Recombinant Fusion Proteins: 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.Chloroplasts: Plant cell inclusion bodies that contain the photosynthetic pigment CHLOROPHYLL, which is associated with the membrane of THYLAKOIDS. Chloroplasts occur in cells of leaves and young stems of plants. They are also found in some forms of PHYTOPLANKTON such as HAPTOPHYTA; DINOFLAGELLATES; DIATOMS; and CRYPTOPHYTA.Coated Vesicles: Vesicles formed when cell-membrane coated pits (COATED PITS, CELL-MEMBRANE) invaginate and pinch off. The outer surface of these vesicles are covered with a lattice-like network of coat proteins, such as CLATHRIN, coat protein complex proteins, or CAVEOLINS.Proteins: 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.Endosomes: Cytoplasmic vesicles formed when COATED VESICLES shed their CLATHRIN coat. Endosomes internalize macromolecules bound by receptors on the cell surface.Protein Processing, Post-Translational: Any of various enzymatically catalyzed post-translational modifications of PEPTIDES or PROTEINS in the cell of origin. These modifications include carboxylation; HYDROXYLATION; ACETYLATION; PHOSPHORYLATION; METHYLATION; GLYCOSYLATION; ubiquitination; oxidation; proteolysis; and crosslinking and result in changes in molecular weight and electrophoretic motility.Coat Protein Complex I: A protein complex comprised of COATOMER PROTEIN and ADP RIBOSYLATION FACTOR 1. It is involved in transport of vesicles between the ENDOPLASMIC RETICULUM and the GOLGI APPARATUS.Cell Line: Established cell cultures that have the potential to propagate indefinitely.Electron Transport: The process by which ELECTRONS are transported from a reduced substrate to molecular OXYGEN. (From Bennington, Saunders Dictionary and Encyclopedia of Laboratory Medicine and Technology, 1984, p270)Endoplasmic Reticulum, Rough: A type of endoplasmic reticulum (ER) where polyribosomes are present on the cytoplasmic surfaces of the ER membranes. This form of ER is prominent in cells specialized for protein secretion and its principal function is to segregate proteins destined for export or intracellular utilization.Cytoplasm: 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)Organelles: Specific particles of membrane-bound organized living substances present in eukaryotic cells, such as the MITOCHONDRIA; the GOLGI APPARATUS; ENDOPLASMIC RETICULUM; LYSOSOMES; PLASTIDS; and VACUOLES.rab1 GTP-Binding Proteins: A genetically related subfamily of RAB GTP-BINDING PROTEINS involved in vesicle transport between the ENDOPLASMIC RETICULUM and the GOLGI APPARATUS and through early Golgi compartments. This enzyme was formerly listed as EC Concentration: The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH = log 1/2[1/(H+)], where (H+) is the hydrogen ion concentration in gram equivalents per liter of solution. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Microscopy, Electron: 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.Protein Binding: 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.ADP-Ribosylation Factors: MONOMERIC GTP-BINDING PROTEINS that were initially recognized as allosteric activators of the MONO(ADP-RIBOSE) TRANSFERASE of the CHOLERA TOXIN catalytic subunit. They are involved in vesicle trafficking and activation of PHOSPHOLIPASE D. This enzyme was formerly listed as EC Enzymes that act at a free C-terminus of a polypeptide to liberate a single amino acid residue.Plant Proteins: Proteins found in plants (flowers, herbs, shrubs, trees, etc.). The concept does not include proteins found in vegetables for which VEGETABLE PROTEINS is available.Bacterial Proteins: Proteins found in any species of bacterium.Adenosine Triphosphatases: 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.Protein PrecursorsMembrane Glycoproteins: Glycoproteins found on the membrane or surface of cells.Sodium: A member of the alkali group of metals. It has the atomic symbol Na, atomic number 11, and atomic weight 23.Nuclear Pore Complex Proteins: Proteins that form the structure of the NUCLEAR PORE. They are involved in active, facilitated and passive transport of molecules in and out of the CELL NUCLEUS.Adenosine Triphosphate: 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.Cloning, Molecular: 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.Escherichia coli Proteins: Proteins obtained from ESCHERICHIA COLI.Escherichia coli: A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.Sequence Homology, Amino Acid: The degree of similarity between sequences of amino acids. This information is useful for the analyzing genetic relatedness of proteins and species.Green Fluorescent Proteins: 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.Endocytosis: Cellular uptake of extracellular materials within membrane-limited vacuoles or microvesicles. ENDOSOMES play a central role in endocytosis.Base Sequence: The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.ADP-Ribosylation Factor 1: ADP-RIBOSYLATION FACTOR 1 is involved in regulating intracellular transport by modulating the interaction of coat proteins with organelle membranes in the early secretory pathway. It is a component of COAT PROTEIN COMPLEX I. This enzyme was formerly listed as EC Chaperones: A family of cellular proteins that mediate the correct assembly or disassembly of polypeptides and their associated ligands. Although they take part in the assembly process, molecular chaperones are not components of the final structures.Active Transport, Cell Nucleus: Gated transport mechanisms by which proteins or RNA are moved across the NUCLEAR MEMBRANE.Temperature: The property of objects that determines the direction of heat flow when they are placed in direct thermal contact. The temperature is the energy of microscopic motions (vibrational and translational) of the particles of atoms.Masoprocol: A potent lipoxygenase inhibitor that interferes with arachidonic acid metabolism. The compound also inhibits formyltetrahydrofolate synthetase, carboxylesterase, and cyclooxygenase to a lesser extent. It also serves as an antioxidant in fats and oils.ran GTP-Binding Protein: A monomeric GTP-binding protein involved in nucleocytoplasmic transport of proteins into the nucleus and RNA into the cytoplasm. This enzyme was formerly listed as EC, Fungal: The functional hereditary units of FUNGI.Melanotrophs: Neuroendocrine cells in the INTERMEDIATE LOBE OF PITUITARY. They produce MELANOCYTE STIMULATING HORMONES and other peptides from the post-translational processing of pro-opiomelanocortin (POMC).Protein Structure, Tertiary: 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.Viral Envelope Proteins: Layers of protein which surround the capsid in animal viruses with tubular nucleocapsids. The envelope consists of an inner layer of lipids and virus specified proteins also called membrane or matrix proteins. The outer layer consists of one or more types of morphological subunits called peplomers which project from the viral envelope; this layer always consists of glycoproteins.Glycosylation: The chemical or biochemical addition of carbohydrate or glycosyl groups to other chemicals, especially peptides or proteins. Glycosyl transferases are used in this biochemical reaction.Cytosol: Intracellular fluid from the cytoplasm after removal of ORGANELLES and other insoluble cytoplasmic components.Cricetinae: A subfamily in the family MURIDAE, comprising the hamsters. Four of the more common genera are Cricetus, CRICETULUS; MESOCRICETUS; and PHODOPUS.Subcellular Fractions: Components of a cell produced by various separation techniques which, though they disrupt the delicate anatomy of a cell, preserve the structure and physiology of its functioning constituents for biochemical and ultrastructural analysis. (From Alberts et al., Molecular Biology of the Cell, 2d ed, p163)Microsomes: Artifactual vesicles formed from the endoplasmic reticulum when cells are disrupted. They are isolated by differential centrifugation and are composed of three structural features: rough vesicles, smooth vesicles, and ribosomes. Numerous enzyme activities are associated with the microsomal fraction. (Glick, Glossary of Biochemistry and Molecular Biology, 1990; from Rieger et al., Glossary of Genetics: Classical and Molecular, 5th ed)Clinical Chemistry Tests: Laboratory tests demonstrating the presence of physiologically significant substances in the blood, urine, tissue, and body fluids with application to the diagnosis or therapy of disease.Cells, Cultured: 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.GTP-Binding Proteins: 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.-.Cell Nucleus: 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)Monensin: An antiprotozoal agent produced by Streptomyces cinnamonensis. It exerts its effect during the development of first-generation trophozoites into first-generation schizonts within the intestinal epithelial cells. It does not interfere with hosts' development of acquired immunity to the majority of coccidial species. Monensin is a sodium and proton selective ionophore and is widely used as such in biochemical studies.Microscopy, Fluorescence: 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.Anion Transport Proteins: Membrane proteins whose primary function is to facilitate the transport of negatively charged molecules (anions) across a biological membrane.Dogs: The domestic dog, Canis familiaris, comprising about 400 breeds, of the carnivore family CANIDAE. They are worldwide in distribution and live in association with people. (Walker's Mammals of the World, 5th ed, p1065)Luminescent 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.Cation Transport Proteins: Membrane proteins whose primary function is to facilitate the transport of positively charged molecules (cations) across a biological membrane.Yeasts: A general term for single-celled rounded fungi that reproduce by budding. Brewers' and bakers' yeasts are SACCHAROMYCES CEREVISIAE; therapeutic dried yeast is YEAST, DRIED.Microscopy, Immunoelectron: Microscopy in which the samples are first stained immunocytochemically and then examined using an electron microscope. Immunoelectron microscopy is used extensively in diagnostic virology as part of very sensitive immunoassays.Qa-SNARE Proteins: A subfamily of Q-SNARE PROTEINS which occupy the same position as syntaxin 1A in the SNARE complex and which also are most similar to syntaxin 1A in their AMINO ACID SEQUENCE. This subfamily is also known as the syntaxins, although a few so called syntaxins are Qc-SNARES.Recombinant Proteins: Proteins prepared by recombinant DNA technology.Diffusion: The tendency of a gas or solute to pass from a point of higher pressure or concentration to a point of lower pressure or concentration and to distribute itself throughout the available space. Diffusion, especially FACILITATED DIFFUSION, is a major mechanism of BIOLOGICAL TRANSPORT.Microtubules: 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.N-Ethylmaleimide-Sensitive Proteins: ATPases that are members of the AAA protein superfamily (ATPase family Associated with various cellular Activities). The NSFs functions, acting in conjunction with SOLUBLE NSF ATTACHMENT PROTEINS (i.e. SNAPs, which have no relation to SNAP 25), are to dissociate SNARE complexes.Genetic Complementation Test: A test used to determine whether or not complementation (compensation in the form of dominance) will occur in a cell with a given mutant phenotype when another mutant genome, encoding the same mutant phenotype, is introduced into that cell.Adaptor Proteins, Vesicular Transport: A class of proteins involved in the transport of molecules via TRANSPORT VESICLES. They perform functions such as binding to the cell membrane, capturing cargo molecules and promoting the assembly of CLATHRIN. The majority of adaptor proteins exist as multi-subunit complexes, however monomeric varieties have also been found.HeLa Cells: 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.Glucose: A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement.Cell Fractionation: Techniques to partition various components of the cell into SUBCELLULAR FRACTIONS.Glycoside HydrolasesProton-Motive Force: Energy that is generated by the transfer of protons or electrons across an energy-transducing membrane and that can be used for chemical, osmotic, or mechanical work. Proton-motive force can be generated by a variety of phenomena including the operation of an electron transport chain, illumination of a PURPLE MEMBRANE, and the hydrolysis of ATP by a proton ATPase. (From Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed, p171)Protein Synthesis Inhibitors: Compounds which inhibit the synthesis of proteins. They are usually ANTI-BACTERIAL AGENTS or toxins. Mechanism of the action of inhibition includes the interruption of peptide-chain elongation, the blocking the A site of ribosomes, the misreading of the genetic code or the prevention of the attachment of oligosaccharide side chains to glycoproteins.Sequence Alignment: The arrangement of two or more amino acid or base sequences from an organism or organisms in such a way as to align areas of the sequences sharing common properties. The degree of relatedness or homology between the sequences is predicted computationally or statistically based on weights assigned to the elements aligned between the sequences. This in turn can serve as a potential indicator of the genetic relatedness between the organisms.Amino Acid Transport Systems: Cellular proteins and protein complexes that transport amino acids across biological membranes.Guanine Nucleotide Exchange Factors: Protein factors that promote the exchange of GTP for GDP bound to GTP-BINDING PROTEINS.CHO Cells: CELL LINE derived from the ovary of the Chinese hamster, Cricetulus griseus (CRICETULUS). The species is a favorite for cytogenetic studies because of its small chromosome number. The cell line has provided model systems for the study of genetic alterations in cultured mammalian cells.GTP Phosphohydrolases: Enzymes that hydrolyze GTP to GDP. EC 3.6.1.-.Nuclear Envelope: The membrane system of the CELL NUCLEUS that surrounds the nucleoplasm. It consists of two concentric membranes separated by the perinuclear space. The structures of the envelope where it opens to the cytoplasm are called the nuclear pores (NUCLEAR PORE).Time Factors: Elements of limited time intervals, contributing to particular results or situations.Mitochondria: Semiautonomous, self-reproducing organelles that occur in the cytoplasm of all cells of most, but not all, eukaryotes. Each mitochondrion is surrounded by a double limiting membrane. The inner membrane is highly invaginated, and its projections are called cristae. Mitochondria are the sites of the reactions of oxidative phosphorylation, which result in the formation of ATP. They contain distinctive RIBOSOMES, transfer RNAs (RNA, TRANSFER); AMINO ACYL T RNA SYNTHETASES; and elongation and termination factors. Mitochondria depend upon genes within the nucleus of the cells in which they reside for many essential messenger RNAs (RNA, MESSENGER). Mitochondria are believed to have arisen from aerobic bacteria that established a symbiotic relationship with primitive protoeukaryotes. (King & Stansfield, A Dictionary of Genetics, 4th ed)Guanosine Triphosphate: Guanosine 5'-(tetrahydrogen triphosphate). A guanine nucleotide containing three phosphate groups esterified to the sugar moiety.Transfection: 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.Models, Molecular: Models used experimentally or theoretically to study molecular shape, electronic properties, or interactions; includes analogous molecules, computer-generated graphics, and mechanical structures.Monomeric GTP-Binding Proteins: A class of monomeric, low molecular weight (20-25 kDa) GTP-binding proteins that regulate a variety of intracellular processes. The GTP bound form of the protein is active and limited by its inherent GTPase activity, which is controlled by an array of GTPase activators, GDP dissociation inhibitors, and guanine nucleotide exchange factors. This enzyme was formerly listed as EC Inorganic compounds derived from hydrochloric acid that contain the Cl- ion.Lysosomes: A class of morphologically heterogeneous cytoplasmic particles in animal and plant tissues characterized by their content of hydrolytic enzymes and the structure-linked latency of these enzymes. The intracellular functions of lysosomes depend on their lytic potential. The single unit membrane of the lysosome acts as a barrier between the enzymes enclosed in the lysosome and the external substrate. The activity of the enzymes contained in lysosomes is limited or nil unless the vesicle in which they are enclosed is ruptured. Such rupture is supposed to be under metabolic (hormonal) control. (From Rieger et al., Glossary of Genetics: Classical and Molecular, 5th ed)Protein Conformation: 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).Plasmids: Extrachromosomal, usually CIRCULAR DNA molecules that are self-replicating and transferable from one organism to another. They are found in a variety of bacterial, archaeal, fungal, algal, and plant species. They are used in GENETIC ENGINEERING as CLONING VECTORS.Nocodazole: Nocodazole is an antineoplastic agent which exerts its effect by depolymerizing microtubules.Receptors, Peptide: Cell surface receptors that bind peptide messengers with high affinity and regulate intracellular signals which influence the behavior of cells.Mitochondrial Membrane Transport Proteins: Proteins involved in the transport of specific substances across the membranes of the MITOCHONDRIA.Cell-Free System: A fractionated cell extract that maintains a biological function. A subcellular fraction isolated by ultracentrifugation or other separation techniques must first be isolated so that a process can be studied free from all of the complex side reactions that occur in a cell. The cell-free system is therefore widely used in cell biology. (From Alberts et al., Molecular Biology of the Cell, 2d ed, p166)Albumins: Water-soluble proteins found in egg whites, blood, lymph, and other tissues and fluids. They coagulate upon heating.Symporters: Membrane transporters that co-transport two or more dissimilar molecules in the same direction across a membrane. Usually the transport of one ion or molecule is against its electrochemical gradient and is "powered" by the movement of another ion or molecule with its electrochemical gradient.Binding Sites: The parts of a macromolecule that directly participate in its specific combination with another molecule.MethylglucosidesAdaptor Protein Complex 1: A clathrin adaptor protein complex primarily involved in clathrin-related transport at the TRANS-GOLGI NETWORK.Vesicular stomatitis Indiana virus: The type species of VESICULOVIRUS causing a disease symptomatically similar to FOOT-AND-MOUTH DISEASE in cattle, horses, and pigs. It may be transmitted to other species including humans, where it causes influenza-like symptoms.RNA, Messenger: 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.Cell Polarity: Orientation of intracellular structures especially with respect to the apical and basolateral domains of the plasma membrane. Polarized cells must direct proteins from the Golgi apparatus to the appropriate domain since tight junctions prevent proteins from diffusing between the two domains.Peptides: Members of the class of compounds composed of AMINO ACIDS joined together by peptide bonds between adjacent amino acids into linear, branched or cyclical structures. OLIGOPEPTIDES are composed of approximately 2-12 amino acids. Polypeptides are composed of approximately 13 or more amino acids. PROTEINS are linear polypeptides that are normally synthesized on RIBOSOMES.Arabidopsis: A plant genus of the family BRASSICACEAE that contains ARABIDOPSIS PROTEINS and MADS DOMAIN PROTEINS. The species A. thaliana is used for experiments in classical plant genetics as well as molecular genetic studies in plant physiology, biochemistry, and development.Phospholipid Transfer Proteins: A ubiquitous family of proteins that transport PHOSPHOLIPIDS such as PHOSPHATIDYLINOSITOL and PHOSPHATIDYLCHOLINE between membranes. They play an important role in phospholipid metabolism during vesicular transport and SIGNAL TRANSDUCTION.SNARE Proteins: A superfamily of small proteins which are involved in the MEMBRANE FUSION events, intracellular protein trafficking and secretory processes. They share a homologous SNARE motif. The SNARE proteins are divided into subfamilies: QA-SNARES; QB-SNARES; QC-SNARES; and R-SNARES. The formation of a SNARE complex (composed of one each of the four different types SNARE domains (Qa, Qb, Qc, and R)) mediates MEMBRANE FUSION. Following membrane fusion SNARE complexes are dissociated by the NSFs (N-ETHYLMALEIMIDE-SENSITIVE FACTORS), in conjunction with SOLUBLE NSF ATTACHMENT PROTEIN, i.e., SNAPs (no relation to SNAP 25.)3-O-Methylglucose: A non-metabolizable glucose analogue that is not phosphorylated by hexokinase. 3-O-Methylglucose is used as a marker to assess glucose transport by evaluating its uptake within various cells and organ systems. (J Neurochem 1993;60(4):1498-504)Mutagenesis, Site-Directed: Genetically engineered MUTAGENESIS at a specific site in the DNA molecule that introduces a base substitution, or an insertion or deletion.Ovum Transport: Transport of the OVUM or fertilized ovum (ZYGOTE) from the mammalian oviduct (FALLOPIAN TUBES) to the site of EMBRYO IMPLANTATION in the UTERUS.ATP-Binding Cassette Transporters: A family of MEMBRANE TRANSPORT PROTEINS that require ATP hydrolysis for the transport of substrates across membranes. The protein family derives its name from the ATP-binding domain found on the protein.Signal Recognition Particle: A cytosolic ribonucleoprotein complex that acts to induce elongation arrest of nascent presecretory and membrane proteins until the ribosome becomes associated with the rough endoplasmic reticulum. It consists of a 7S RNA and at least six polypeptide subunits (relative molecular masses 9, 14, 19, 54, 68, and 72K).Membrane Fusion: The adherence and merging of cell membranes, intracellular membranes, or artificial membranes to each other or to viruses, parasites, or interstitial particles through a variety of chemical and physical processes.Plants: Multicellular, eukaryotic life forms of kingdom Plantae (sensu lato), comprising the VIRIDIPLANTAE; RHODOPHYTA; and GLAUCOPHYTA; all of which acquired chloroplasts by direct endosymbiosis of CYANOBACTERIA. They are characterized by a mainly photosynthetic mode of nutrition; essentially unlimited growth at localized regions of cell divisions (MERISTEMS); cellulose within cells providing rigidity; the absence of organs of locomotion; absence of nervous and sensory systems; and an alternation of haploid and diploid generations.Macromolecular Substances: 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.Clathrin: The main structural coat protein of COATED VESICLES which play a key role in the intracellular transport between membranous organelles. Each molecule of clathrin consists of three light chains (CLATHRIN LIGHT CHAINS) and three heavy chains (CLATHRIN HEAVY CHAINS) that form a structure called a triskelion. Clathrin also interacts with cytoskeletal proteins.DNA, Complementary: Single-stranded complementary DNA synthesized from an RNA template by the action of RNA-dependent DNA polymerase. cDNA (i.e., complementary DNA, not circular DNA, not C-DNA) is used in a variety of molecular cloning experiments as well as serving as a specific hybridization probe.Fluorescent Antibody Technique: 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.Amino Acid Transport Systems, Basic: Amino acid transporter systems capable of transporting basic amino acids (AMINO ACIDS, BASIC).Microtubule-Associated Proteins: High molecular weight proteins found in the MICROTUBULES of the cytoskeletal system. Under certain conditions they are required for TUBULIN assembly into the microtubules and stabilize the assembled microtubules.Microscopy, Confocal: 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.Signal Transduction: 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.Potassium: An element in the alkali group of metals with an atomic symbol K, atomic number 19, and atomic weight 39.10. It is the chief cation in the intracellular fluid of muscle and other cells. Potassium ion is a strong electrolyte that plays a significant role in the regulation of fluid volume and maintenance of the WATER-ELECTROLYTE BALANCE.Arabidopsis Proteins: Proteins that originate from plants species belonging to the genus ARABIDOPSIS. The most intensely studied species of Arabidopsis, Arabidopsis thaliana, is commonly used in laboratory experiments.Nuclear Proteins: Proteins found in the nucleus of a cell. Do not confuse with NUCLEOPROTEINS which are proteins conjugated with nucleic acids, that are not necessarily present in the nucleus.DNA Primers: Short sequences (generally about 10 base pairs) of DNA that are complementary to sequences of messenger RNA and allow reverse transcriptases to start copying the adjacent sequences of mRNA. Primers are used extensively in genetic and molecular biology techniques.RNA Transport: The process of moving specific RNA molecules from one cellular compartment or region to another by various sorting and transport mechanisms.Amino Acid Transport Systems, Neutral: Amino acid transporter systems capable of transporting neutral amino acids (AMINO ACIDS, NEUTRAL).Blotting, Western: 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.MethylglycosidesOrganic Cation Transport Proteins: A family of proteins involved in the transport of organic cations. They play an important role in the elimination of a variety of endogenous substances, xenobiotics, and their metabolites from the body.Cricetulus: A genus of the family Muridae consisting of eleven species. C. migratorius, the grey or Armenian hamster, and C. griseus, the Chinese hamster, are the two species used in biomedical research.Proton-Translocating ATPases: Multisubunit enzymes that reversibly synthesize ADENOSINE TRIPHOSPHATE. They are coupled to the transport of protons across a membrane.Two-Hybrid System Techniques: 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.GTPase-Activating Proteins: Proteins that activate the GTPase of specific GTP-BINDING PROTEINS.Electrophoresis, Polyacrylamide Gel: Electrophoresis in which a polyacrylamide gel is used as the diffusion medium.Microinjections: The injection of very small amounts of fluid, often with the aid of a microscope and microsyringes.Liver: A large lobed glandular organ in the abdomen of vertebrates that is responsible for detoxification, metabolism, synthesis and storage of various substances.Plant Leaves: Expanded structures, usually green, of vascular plants, characteristically consisting of a bladelike expansion attached to a stem, and functioning as the principal organ of photosynthesis and transpiration. (American Heritage Dictionary, 2d ed)Amino Acids: Organic compounds that generally contain an amino (-NH2) and a carboxyl (-COOH) group. Twenty alpha-amino acids are the subunits which are polymerized to form proteins.Heat-Shock Proteins: Proteins which are synthesized in eukaryotic organisms and bacteria in response to hyperthermia and other environmental stresses. They increase thermal tolerance and perform functions essential to cell survival under these conditions.Phenotype: The outward appearance of the individual. It is the product of interactions between genes, and between the GENOTYPE and the environment.Arginine: An essential amino acid that is physiologically active in the L-form.Molecular Weight: The sum of the weight of all the atoms in a molecule.Glucose Transport Proteins, Facilitative: A family of monosaccharide transport proteins characterized by 12 membrane spanning helices. They facilitate passive diffusion of GLUCOSE across the CELL MEMBRANE.Exocytosis: Cellular release of material within membrane-limited vesicles by fusion of the vesicles with the CELL MEMBRANE.HSP70 Heat-Shock Proteins: A class of MOLECULAR CHAPERONES found in both prokaryotes and in several compartments of eukaryotic cells. These proteins can interact with polypeptides during a variety of assembly processes in such a way as to prevent the formation of nonfunctional structures.Nerve Tissue ProteinsEpithelial Cells: 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.Aminoisobutyric Acids: A group of compounds that are derivatives of the amino acid 2-amino-2-methylpropanoic acid.Mutagenesis: Process of generating a genetic MUTATION. It may occur spontaneously or be induced by MUTAGENS.Deoxyglucose: 2-Deoxy-D-arabino-hexose. An antimetabolite of glucose with antiviral activity.COS Cells: 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).)Protein Biosynthesis: The biosynthesis of PEPTIDES and PROTEINS on RIBOSOMES, directed by MESSENGER RNA, via TRANSFER RNA that is charged with standard proteinogenic AMINO ACIDS.Microvilli: Minute projections of cell membranes which greatly increase the surface area of the cell.Photosynthetic Reaction Center Complex Proteins: Protein complexes that take part in the process of PHOTOSYNTHESIS. They are located within the THYLAKOID MEMBRANES of plant CHLOROPLASTS and a variety of structures in more primitive organisms. There are two major complexes involved in the photosynthetic process called PHOTOSYSTEM I and PHOTOSYSTEM II.Cell Membrane Permeability: A quality of cell membranes which permits the passage of solvents and solutes into and out of cells.Intestinal Absorption: Uptake of substances through the lining of the INTESTINES.PhloretinGene Deletion: A genetic rearrangement through loss of segments of DNA or RNA, bringing sequences which are normally separated into close proximity. This deletion may be detected using cytogenetic techniques and can also be inferred from the phenotype, indicating a deletion at one specific locus.Hydrolysis: The process of cleaving a chemical compound by the addition of a molecule of water.Transportation: The means of moving persons, animals, goods, or materials from one place to another.Anions: Negatively charged atoms, radicals or groups of atoms which travel to the anode or positive pole during electrolysis.Membrane Transport Modulators: Agents that affect ION PUMPS; ION CHANNELS; ABC TRANSPORTERS; and other MEMBRANE TRANSPORT PROTEINS.Glycoproteins: Conjugated protein-carbohydrate compounds including mucins, mucoid, and amyloid glycoproteins.

A novel in vivo assay for the analysis of protein-protein interaction. (1/21932)

The Ras Recruitment System (RRS) is a method for identification and isolation of protein-protein interaction. The method is based on translocation of cytoplasmic mammalian Ras protein to the inner leaflet of the plasma membrane through protein-protein interaction. The system is studied in a temperature-sensitive yeast strain where the yeast Ras guanyl nucleotide exchange factor is inactive at 36 degrees C. Protein-protein interaction results in cell growth at the restrictive temperature. We developed a gene reporter assay for the analysis of protein-protein interaction in mammalian cells. Ras activation in mammalian cells induces the mitogen-activated kinase cascade (MAPK), which can be monitored using Ras-dependent reporter genes. This greatly extends the usefulness of the system and provides a novel assay for protein-protein interaction in mammalian cells.  (+info)

Decisive structural determinants for the interaction of proline derivatives with the intestinal H+/peptide symporter. (2/21932)

To elucidate the decisive structural factors relevant for dipeptide-carrier interaction, the affinity of short amide and imide derivatives for the intestinal H+/peptide symporter (PEPT1) was investigated by measuring their ability to inhibit Gly-Sar transport in Caco-2 cells. Dipeptides with proline or alanine in the C-terminal position displayed affinity constants (Ki) of 0.15-1.2 mM and 0.08-9.5 mM, respectively. There was no clear relationship between hydrophobicity, size or ionization status of the N-terminal amino acid and the affinity of the dipeptides. However, analyzing the individual peptide bond conformations of Xaa-Pro dipeptides, a striking correlation between the cis/trans ratios (trans contents 24-70%) and the affinity constants was observed. After correcting the Ki values for the incompetent cis isomers, the Ki corr values of most dipeptides were in a small range of 0.1-0.16 mM. This result revealed the decisive role of peptide bond conformation even for a transport protein that is quite promiscuous in substrate translocation. When measuring affinity constants of Xaa-Pro and Xaa-Sar dipeptides, the cis/trans ratios cannot be ignored. Lower affinities of Lys-Pro, Arg-Pro and Pro-Pro indicate that additional molecular factors affect their binding at PEPT1. The Ki values obtained for the corresponding Xaa-Ala dipeptides support this conclusion. Potential substrates or inhibitors of peptide transport were found among Xaa-piperidides and Xaa-thiazolidides. Dipeptides with N-terminal proline displayed a very diverse affinity profile. However, in contrast to current knowledge, several Pro-Xaa dipeptides such as Pro-Leu, Pro-Tyr and Pro-Pro are recognized by PEPT1 with appreciable affinities. Binding seems mainly determined by the hydrophobicity of the C-terminal amino acid and the rigidity of the structure.  (+info)

Involvement of proline-rich tyrosine kinase 2 in platelet activation: tyrosine phosphorylation mostly dependent on alphaIIbbeta3 integrin and protein kinase C, translocation to the cytoskeleton and association with Shc through Grb2. (3/21932)

Proline-rich tyrosine kinase 2 (Pyk2) (also known as RAFTK, CAKbeta or CADTK) has been identified as a member of the focal adhesion kinase (FAK) family of protein-tyrosine kinases and it has been suggested that the mode of Pyk2 activation is distinct from that of FAK. In the present study we investigated the mode of Pyk2 activation in human platelets. When platelets were stimulated with thrombin, Pyk2, as well as FAK, was markedly tyrosine-phosphorylated, in a manner mostly dependent on alphaIIbbeta3 integrin-mediated aggregation. The residual Pyk2 tyrosine phosphorylation observed in the absence of platelet aggregation was completely abolished by pretreatment with BAPTA/AM [bis-(o-aminophenoxy)ethane-N,N,N',N'-tetra-acetic acid acetoxymethyl ester]. The Pyk2 phosphorylation was inhibited by protein kinase C (PKC) inhibitors at concentrations that inhibited platelet aggregation. In contrast, direct activation of PKC with the active phorbol ester PMA induced the tyrosine phosphorylation of Pyk2 and FAK but only when platelets were fully aggregated with the exogenous addition of fibrinogen (the ligand for alphaIIbbeta3 integrin). Furthermore, PMA-induced Pyk2 (and FAK) tyrosine phosphorylation was also observed when platelets adhered to immobilized fibrinogen. The activation of the von Willebrand factor (vWF)--glycoprotein Ib pathway with botrocetin together with vWF failed to induce Pyk2 (and FAK) tyrosine phosphorylation. Most Pyk2 and FAK was present in the cytosol and membrane skeleton fractions in unstimulated platelets. When platelets were stimulated with thrombin, both Pyk2 and FAK were translocated to the cytoskeleton in an aggregation-dependent manner. In immunoprecipitation studies, Pyk2, as well as FAK, seemed to associate with Shc through Grb2. With the use of glutathione S-transferase fusion proteins containing Shc-SH2, Grb2-SH2, and Grb2 N-terminal and C-terminal SH3 domains, it was implied that the proline-rich region of Pyk2 (and FAK) binds to the N-terminal SH3 domain of Grb2 and that the phosphotyrosine residue of Shc binds to the SH2 domain of Grb2. Although Pyk2 and FAK have been reported to be differentially regulated in many cell types, our results suggest that, in human platelets, the mode of Pyk2 activation is mostly similar to that of FAK, in terms of alphaIIbbeta3 integrin-dependent and PKC-dependent tyrosine phosphorylation. Furthermore, Pyk2, as well as FAK, might have one or more important roles in post-aggregation tyrosine phosphorylation events, in association with the cytoskeleton and through interaction with adapter proteins including Grb2 and Shc.  (+info)

Aut7p, a soluble autophagic factor, participates in multiple membrane trafficking processes. (4/21932)

Aut7p, a protein recently implicated in autophagic events in the yeast Saccharomyces cerevisiae, exhibits significant homology to a mammalian protein, p16, herein termed GATE-16 (Golgi-associated ATPase Enhancer of 16 kDa), a novel intra-Golgi transport factor. Here we provide evidence for the involvement of Aut7p in different membrane trafficking processes. Aut7p largely substitutes for the activity of GATE-16 in mammalian intra-Golgi transport in vitro. In vivo, AUT7 interacts genetically with endoplasmic reticulum to Golgi SNAREs, specifically with BET1 and SEC22. Aut7p interacts physically with the following two v-SNAREs: Bet1p, which is involved in endoplasmic reticulum to Golgi vesicular transport, and Nyv1p, implicated in vacuolar inheritance. We suggest that, in addition to its role in autophagocytosis, Aut7p has pleiotropic effects and participates in at least two membrane traffic events.  (+info)

Targeting motifs and functional parameters governing the assembly of connexins into gap junctions. (5/21932)

To study the assembly of gap junctions, connexin--green-fluorescent-protein (Cx--GFP) chimeras were expressed in COS-7 and HeLa cells. Cx26-- and Cx32--GFP were targeted to gap junctions where they formed functional channels that transferred Lucifer Yellow. A series of Cx32--GFP chimeras, truncated from the C-terminal cytoplasmic tail, were studied to identify amino acid sequences governing targeting from intracellular assembly sites to the gap junction. Extensive truncation of Cx32 resulted in failure to integrate into membranes. Truncation of Cx32 to residue 207, corresponding to removal of most of the 78 amino acids on the cytoplasmic C-terminal tail, led to arrest in the endoplasmic reticulum and incomplete oligomerization. However, truncation to amino acid 219 did not impair Cx oligomerization and connexon hemichannels were targeted to the plasma membrane. It was concluded that a crucial gap-junction targeting sequence resides between amino acid residues 207 and 219 on the cytoplasmic C-terminal tail of Cx32. Studies of a Cx32E208K mutation identified this as one of the key amino acids dictating targeting to the gap junction, although oligomerization of this site-specific mutation into hexameric hemichannels was relatively unimpaired. The studies show that expression of these Cx--GFP constructs in mammalian cells allowed an analysis of amino acid residues involved in gap-junction assembly.  (+info)

Identification of mammalian TOM22 as a subunit of the preprotein translocase of the mitochondrial outer membrane. (6/21932)

A mitochondrial outer membrane protein of approximately 22 kDa (1C9-2) was purified from Vero cells assessing immunoreactivity with a monoclonal antibody, and the cDNA was cloned based on the partial amino acid sequence of the trypsin-digested fragments. 1C9-2 had 19-20% sequence identity to fungal Tom22, a component of the preprotein translocase of the outer membrane (the TOM complex) with receptor and organizer functions. Despite such a low sequence identity, both shared a remarkable structural similarity in the hydrophobicity profile, membrane topology in the Ncyt-Cin orientation through a transmembrane domain in the middle of the molecule, and the abundant acidic amino acid residues in the N-terminal domain. The antibodies against 1C9-2 inhibited the import of a matrix-targeted preprotein into isolated mitochondria. Blue native polyacrylamide gel electrophoresis of digitonin-solubilized outer membranes revealed that 1C9-2 is firmly associated with TOM40 in the approximately 400-kDa complex, with a size and composition similar to those of the fungal TOM core complex. Furthermore, 1C9-2 complemented the defects of growth and mitochondrial protein import in Deltatom22 yeast cells. Taken together, these results demonstrate that 1C9-2 is a functional homologue of fungal Tom22 and functions as a component of the TOM complex.  (+info)

Inhibition of NFkappaB by methyl chlorogenate from Eriobotrya japonica. (7/21932)

Methylchlorogenic acid (MC) is one of the main components in the leaves of Eriobotrya japonica. We previously reported that MC is the most potent antioxidant among several components of Eriobotrya japonica, and its antioxidant activity is stronger than that of chlorogenic acid. Antioxidants are expected to inhibit redox-sensitive NFkappaB activation since NFkappaB is readily influenced by cellular oxidative state. Based on these findings, in vivo experiments with MC were conducted to determine its ability to downregulate the NFkappaB activation in mouse liver. Results clearly showed that MC is a potent suppressor of BHP-induced NFkappaB activation. We observed a significant reduction by MC on BHP-induced translocation of p65 subunit of NFkappaB. This may be due to formation of p50/p65 heterodimer, which is mainly inducible NFkappaB. MC slightly blocked the BHP-induced IkappaB alpha degradation. There is a possibility of IkappaB alpha resynthesis via activated NFkappaB during a 5 h waiting period following BHP injection. The present results suggest that MC may inhibit NFkappaB activation, exhibiting its ability to downregulate the NFkappaB-dependent gene expression. Thus, it can be expected that MC may have potential for therapeutic intervention on various NFkappaB-dependent pathological conditions such as inflammatory or possibly mutagenic processes.  (+info)

Functional and structural characterization of synthetic HIV-1 Vpr that transduces cells, localizes to the nucleus, and induces G2 cell cycle arrest. (8/21932)

Human immunodeficiency virus (HIV) Vpr contributes to nuclear import of the viral pre-integration complex and induces G(2) cell cycle arrest. We describe the production of synthetic Vpr that permitted the first studies on the structure and folding of the full-length protein. Vpr is unstructured at neutral pH, whereas under acidic conditions or upon addition of trifluorethanol it adopts alpha-helical structures. Vpr forms dimers in aqueous trifluorethanol, whereas oligomers exist in pure water. (1)H NMR spectroscopy allows the signal assignment of N- and C-terminal amino acid residues; however, the central section of the molecule is obscured by self-association. These findings suggest that the in vivo folding of Vpr may require structure-stabilizing interacting factors such as previously described interacting cellular and viral proteins or nucleic acids. In biological studies we found that Vpr is efficiently taken up from the extracellular medium by cells in a process that occurs independent of other HIV-1 proteins and appears to be independent of cellular receptors. Following cellular uptake, Vpr is efficiently imported into the nucleus of transduced cells. Extracellular addition of Vpr induces G(2) cell cycle arrest in dividing cells. Together, these findings raise the possibility that circulating forms of Vpr observed in HIV-infected patients may exert biological effects on a broad range of host target cells.  (+info)

  • Research by University at Buffalo biologists is providing new insights into alpha-synuclein, a small acidic protein associated with Parkinson's disease. (
  • The scientists found that when the larvae are engineered to produce both excess alpha-synuclein and a version of alpha-synuclein with the NAC region missing, the larvae crawl normally, the protein doesn't aggregate, and the synapses are normal. (
  • In addition to a defect in glucose uptake, the cdc25-5 mutant strain exhibited differences in glucose metabolism, probably due to the decreased cAMP level and hence decreased protein kinase A activity. (
  • It has been hypothesized on the basis of studies on BC3H-1 myocytes that diacylglycerol generation with activation of protein kinase C (PKC) is involved in the stimulation of glucose transport in muscle by insulin. (
  • We have hypothesized that the 5′AMP-activated protein kinase (AMPK) functions as a signaling intermediary in exercise-stimulated glucose uptake. (
  • The phosphatidylinositol 3-kinase (PI 3-kinase) inhibitor wortmannin completely blocked insulin-stimulated transport, but did not inhibit AICAR- or contraction-stimulated transport. (
  • The PINOID gene was recently cloned and found to encode a protein-serine/threonine kinase. (
  • Here we show that the PINOID gene is inducible by auxin and that the protein kinase is present in the primordia of cotyledons, leaves and floral organs and in vascular tissue in developing organs or proximal to meristems. (
  • article{4103eda6-97a4-45fe-8b8c-d30ec247d415, abstract = {Many of the core proteins in Photosystem II (PS II) undergo reversible phosphorylation. (
  • Perez-Gonzalez A, Rodriguez A, Huarte M, Salanueva IJ, Nieto A. hCLE/CGI-99, a human protein that interacts with the influenza virus polymerase, is a mRNA transcription modulator. (
  • Transport of mRNA to distal compartments in neurons, such as growth cones and dendritic spines, ensures local translation of proteins in response to receptor signaling. (
  • its contribution to the trafficking of mRNA binding proteins important for mRNA localization is not well understood. (
  • Myelin basic protein (MBP) mRNA is localized to myelin produced by oligodendrocytes of the central nervous system. (
  • MBP mRNA microinjected into oligodendrocytes in primary culture is assembled into granules in the perikaryon, transported along the processes, and localized to the myelin compartment. (
  • In this work, microinjection of various deleted and chimeric RNAs was used to delineate regions in MBP mRNA that are required for transport and localization in oligodendrocytes. (
  • The results indicate that transport requires a 21-nucleotide sequence, termed the RNA transport signal (RTS), in the 3′ UTR of MBP mRNA. (
  • Insertion of the RTS from MBP mRNA into nontransported mRNAs, causes the RNA to be transported to the oligodendrocyte processes. (
  • If the coding region of the mRNA is deleted, the RLR is no longer required for localization, and the region between nucleotide 667 and 953, containing the RTS, is sufficient for both RNA transport and localization. (
  • This provided evidence that mRNA encoding a protein synthesized on free polysomes was spatially localized within the cell. (
  • Transport and localization of exogenous myelin basic protein mRNA microinjected into oligodendrocytes. (
  • We have studied transport and localization of MBP mRNA in oligodendrocytes in culture by microinjecting labeled mRNA into living cells and analyzing the intracellular distribution of the injected RNA by confocal microscopy. (
  • Within minutes, the RNA forms granules which, in the case of MBP mRNA, are transported down the processes to the periphery of the cell where the distribution again becomes dispersed. (
  • This work represents the first characterization of intracellular movement of mRNA in living cells, and the first description of the role of RNA granules in transport and localization of mRNA in cells. (
  • Further investigation into the regulation of αENaC by Per1 revealed that cortical αENaC mRNA was reduced in Per1 KO mice, and Per1 knockdown resulted in reduced αENaC protein levels in immortalized murine renal cortical CD (CCD) mpkCCD c14 cells. (
  • In addition to Cu acquisition, SPL7 triggers the expression of various microRNAs, denoted Cu-microRNAs, which promote the degradation of the transcripts encoding for dispensable Cu-utilizing proteins, including cytosolic Cu/Zn-SOD ( CSD1 ), chloroplast stroma Cu/Zn-SOD ( CSD2 ), several laccases, and plantacyanin [ 9 , 14 - 16 ]. (
  • Thereby, Xdj1 promotes the transfer of precursory proteins from the cytosolic chaperones to the TOM complex to initiate their import into the mitochondria . (
  • Recruitment of Cytosolic J-Proteins by TOM Receptors Promotes Mitochondrial Protein Biogenesis, Cell Reports (2018). (
  • You can select a given mouse superfamily member and download (or forward to NCBI BLAST) FASTA formatted protein sequences of that mouse gene and its mouse, human and rat homologs, as defined in the corresponding HomoloGene Class. (
  • p>This section provides information about the protein and gene name(s) and synonym(s) and about the organism that is the source of the protein sequence. (
  • section indicates the name(s) of the gene(s) that code for the protein sequence(s) described in the entry. (
  • One of these polypeptides, termed Erv14p (ER-vesicle protein of 14 kD), corresponds to an open reading frame on yeast chromosome VII that is predicted to encode an integral membrane protein and shares sequence identity with the Drosophila cornichon gene product. (
  • p>Describes annotations that are concluded from looking at variations or changes in a gene product such as mutations or abnormal levels and includes techniques such as knockouts, overexpression, anti-sense experiments and use of specific protein inhibitors. (
  • 4 Circadian clock proteins interact with E-box response elements in target gene promoters to affect transcriptional regulation. (
  • This gene encodes a member of the WD repeat protein family. (
  • Death-associated protein 6 also known as Daxx is a protein that in humans is encoded by the DAXX gene. (
  • Half a century later this idea has turned into one of the most studied of all transporter proteins (SGLT1), the sodium-glucose cotransporter. (
  • The BK virus genome encodes three regulatory proteins, large and small tumor-antigen and the agnoprotein, as well as the capsid proteins VP1 to VP3. (
  • The lipid A-core moiety and the O-antigen repeat units are synthesized at the cytoplasmic face of the IM and are separately exported via two independent transport systems, namely, the O-antigen transporter Wzx ( 13 , 17 ) and the ATP binding cassette (ABC) transporter MsbA that flips the lipid A-core moiety from the inner leaflet to the outer leaflet of the IM ( 12 , 28 , 45 ). (
  • It interacts with a wide variety of proteins, such as apoptosis antigen Fas, centromere protein C, and transcription factor erythroblastosis virus E26 oncogene homolog 1 (ETS1). (
  • Transport of proteins into and out of the nucleus occurs through nuclear pore complexes (NPC). (
  • Two additional proteins, the GTPase Ran and p10, are required to translocate the docked NLS protein into the nucleus. (
  • The retina projects proteins into more than 30 different areas of the central nervous system, but for the study, her team chose to evaluate the two major targets: the superior colliculus (which analyzes motion in the visual field and controls goal-directed head and eye movements), and the lateral geniculate nucleus (which analyzes the shape of objects we see and sends that information to a higher brain area, the visual cortex). (
  • These are proteins that are usually in the nucleus of a cell, but we found them far, far away from the nucleus, participating in some form of communication. (
  • Transport of maize streak virus (MSV) DNA into the nucleus of host cells is essential for virus replication and the presence of virus particles in the nuclei of infected cells implies that coat protein (CP) must enter the nucleus. (
  • Both ss and ds DNA moved into the nucleus when co-injected with the CP but not with E. coli proteins alone. (
  • These results suggest that, in addition to entering the nucleus where it is required for encapsidation of the viral ss DNA, the MSV CP facilitates the rapid transport of viral (ss or ds) DNA into the nucleus. (
  • Although some of these nucleus-bound cargoes are essential for life, others cause disease, and researchers have been looking for ways to disrupt the transport chain that can fuel infection and cancer alike. (
  • Most importins, like the importin a1, tow upwards of 500-600 different proteins into the nucleus. (
  • ASK1 will be transported to the nucleus when UV-irradiation is used to treat the cell. (
  • Pathways for water and plasma proteins across the endothelial barrier that may be regulated by ANP. (
  • A ) Pathways for plasma protein transport across the endothelial permeability barrier that ANP may modulate, including water and plasma transport through the interendothelial cleft at sites where there are infrequent breaks in the junctional strand (see refs. (
  • In conclusion, the bidirectional transport of glutamine, glutamate, and aspartate by SLC38A10, and the immunostaining detected in neurons and astrocytes, suggest that SLC38A10 plays a role in pathways involved in neurotransmission. (
  • A related system operates in bacteria, apparently for the export of redox cofactor-containing proteins. (
  • A heterodimeric protein complex, composed of karyopherin alpha and beta (or importin alpha and beta) functions to target proteins containing a nuclear localization sequence (NLS) to the NPCs. (
  • The number of protein sequences returned does not always match the numbers of homologs shown, because the same protein sequence can be associated with multiple homologs. (
  • For mouse superfamily members not included in any HomoloGene Class, only the mouse protein sequence is returned. (
  • View conserved domains detected in this protein sequence using CD-search. (
  • Note that the 'protein existence' evidence does not give information on the accuracy or correctness of the sequence(s) displayed. (
  • Despite exceptional sequence diversity, S-layer proteins (SLPs) share important characteristics such as their ability to form crystalline sheets punctuated with nano-scale pores, and their propensity for charged amino acids, leading to acidic or basic isoelectric points. (
  • In response to Cu limitation, Arabidopsis master Cu homeostasis regulator SPL7 (SQUAMOSA promoter-binding protein-like 7), similar to Chlamydomonas reinhardtii Crr1 transcription factor [ 8 ], activates the expression of multiple genes that contain within their promoter repetitive Cu-responsive elements (CuREs) with a GTAC motif as the essential core sequence [ 9 - 11 ]. (
  • The [ 3 H]LTC 4 -labeled 190-kilodalton protein was immunoprecipitated by an antiserum against the COOH-terminal sequence of multidrug resistance-associated protein. (
  • The multifunctional RNA-binding protein Tudor-SN plays multiple roles in transcriptional and posttranscriptional processes due to its modular domain structure, consisting of four tandem Staphylococcus nuclease (SN)-like domains (4SN), followed by a carboxyl-terminal Tudor domain, followed by a fifth partial SN sequence (Tsn). (
  • Researchers reveal that the protein RCC1's overall structure, not its distinct amino acid sequence, determines whether it's fast-tracked into nuclei. (
  • Retention within the lumen of the ER correlates with an additional signal located at the C terminus, represented by the sequence Lys-Asp-Glu-Leu, known to be responsible for preventing secretion of proteins from the lumen of the ER in eukaryotic cells. (
  • In this project, the first goal is to design a plan to extend already successful in vitro biophysical research on copper transport proteins to (1) zinc and manganese transport proteins, for which less is known, and to (2) in vivo conditions exploring diseases related to problems with metal transport. (
  • Thylakoids require the coordinated expression of both nuclear- and plastid-encoded proteins to allow rapid response to changing environmental conditions. (
  • and proteins that play a direct role in the transport of karyopherin complexes through the nuclear pore complex. (
  • Mutagenesis of a potential nuclear localization signal in the CP resulted in cytoplasmic accumulation of the mutant protein. (
  • To investigate if CP might also be involved in viral DNA nuclear transport, Escherichia coli -expressed CP, together with TOTO-1-labeled viral ss or ds DNA, was microinjected into maize and tobacco epidermal cells. (
  • The importin a3 molecule, or "car," is one of a family of importin proteins that help ferry other proteins across the nuclear membrane where they can alter the course of DNA transcription. (
  • Its repression can be relieved by the sequestration of this protein into promyelocytic leukemia nuclear bodies or nucleoli. (
  • The SemiSWEETs, among the smallest known transport proteins, assemble in pairs, thereby creating a structure that looks like their bigger plant and human SWEET homologs. (
  • Scientists at the University of Groningen studied the structure of a transport system that allows bacteria to pick up aspartate, a building block for proteins, from their environment. (
  • The structure of a transport complex used by bacteria to import aspartate has been mapped in unique detail by University of Groningen scientists. (
  • We have identified sister of open brain ( sopb ), a null allele of mouse Intraflagellar transport protein 122 ( Ift122 ). (
  • These sugars are taken up into cells, no matter whether these are bacteria, yeast, human cells or plant cells, by proteins that create sugar-specific pores in the membrane that surrounds a cell. (
  • In mammals, Rhesus proteins regulate acid and ion balance in kidney and liver cells. (
  • Defective transport of carbohydrates into cells is associated with a range of disorders, including cystic fibrosis, hypercholesterolemia, and diabetes. (
  • And at the root of all eye-to-brain communication are the hundreds of proteins generated by the retina's nerve cells. (
  • Using this new method--developed over the course of several years--Cline's team was able to "label" about 1,000 different types of proteins that originate in the eye's retinal ganglion cells, and then watch how and where they travel in a living brain of a rat. (
  • This can help us study what happens when a person experiences nerve damage and vision loss--and will hopefully lead us to treatments that can enhance protein transport and prevent cells from dying. (
  • The latter is also important for humans: we have a very similar transport system in our brain that plays a vital role in effective communication between brain cells. (
  • Such protein aggregates can be detrimental for cells and are thought to underlie the development of many diseases. (
  • Immunohistochemical analysis of the gw/gw cochlea showed loss of the tight junction protein CLDN11 in strial basal cells from E40, loss of the potassium channel subunit KCNJ10 in strial intermediate cells from E50, and loss of the Na-K-Cl cotransporter SLC12A2 in strial marginal cells from E50. (
  • As part of a study to determine the function of primary cilia in lens we investigated the role of a key component of the intraflagellar transport (IFT) complex, IFT88, in cilia assembly in lens cells. (
  • In mice conditionally deficient for IFT88, the protein was absent from most lens cells, although a few scattered cells did show some reactivity. (
  • This supports tumor growth and metastasis as the exported lactate is taken up into other cancer cells by another transport protein (MCT1), where it serves as fuel. (
  • BKV agnoprotein and α-SNAP were found to partially co-localize in cells, and a complex consisting of agnoprotein and α-SNAP could be co-immunoprecipitated from cells ectopically expressing the proteins as well as from BKV-transfected cells. (
  • All the characteristic features of L-arginine transport displayed by the reconstituted system were similar to those observed in intact cells. (
  • Recent advances in understanding the machinery of vesicle transport have established general principles that underlie a broad variety of physiological processes, including cell surface growth, the biogenesis of distinct intracellular organelles, endocytosis, and the controlled release of hormones and neurotransmitters. (
  • Alcock F, Baker MA, Greene NP, Palmer T, Wallace MI, Berks BC (2013) Live cell imaging shows reversible assembly of the TatA component of the twin-arginine protein transport system. (
  • A new study from Scripps Research , which appears this month in Cell Reports , examines these proteins in unprecedented detail--providing surprising new insights into how visual signals are distributed to different regions of the brain. (
  • Because this type of neuronal protein exists in other parts of the body, it may play a role in other nerve-cell communication disorders such as Charcot-Marie-Tooth disease. (
  • Live cell imaging of mCherryZBP1 in neurons expressing GTD showed an increase in the number of motile particles, run length, and stimulated anterograde moving ZBP1 particles, suggesting that MyoVa controls availability of ZBP1 for microtubule-dependent transport. (
  • Aspartate is picked up from the environment, transported through the cell membrane and released on the inside of the cell. (
  • Homologous sequences are present in several other localized mRNAs, suggesting that the RTS represents a general transport signal in a variety of different cell types. (
  • In order to function properly, mitochondria are dependent on roughly 1,000 kinds of proteins, which are imported from the cytosol, the fluid inside the cell. (
  • In this study, Dr. Cingolani's "cargo" was the RCC1 protein, which has a multitude of functions in the cell, and without which, the cell dies. (
  • In vitro and in vivo measurement of defined cargoes and motors indicated that opposing motors are simultaneously engaged on cargoes that undergo bidirectional transport and suggest a potential for regulation during activation by controlling motor type and number. (
  • It could be proposed therefore that directed ZBP1 transport is carried out by and requires a fine-tuned regulation of multiple microtubule and actin motors. (
  • The current study aimed to investigate radiation-induced regulation of iron proteins including ferritin subunits in rats. (
  • The circadian clock protein period 1 (Per1) contributes to the regulation of expression of the α subunit of the renal epithelial sodium channel at the basal level and in response to the mineralocorticoid hormone aldosterone. (
  • These data support a role for the circadian clock protein Per1 in the coordinate regulation of genes involved in renal sodium reabsorption. (
  • The researchers also investigated the transport properties of SfMCT and possible binding sites for inhibitors. (
  • Both meristem organisation and growth of the primary root were rescued when seedlings were grown in the presence of polar auxin transport inhibitors, such as naphthylphtalamic acid (NPA). (
  • Treatment of seedlings or plant tissues with inhibitors of this polar auxin transport (PAT), such as naphthylphtalamic acid (NPA) or 2,3,5,-triiodo-benzoic acid (TIBA), showed that PAT provides directional and positional information for developmental processes such as vascular differentiation, apical dominance, organ development and tropic growth. (