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.
Cell Membrane
The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells.
Membranes
Membrane Lipids
Lipids, predominantly phospholipids, cholesterol and small amounts of glycolipids found in membranes including cellular and intracellular membranes. These lipids may be arranged in bilayers in the membranes with integral proteins between the layers and peripheral proteins attached to the outside. Membrane lipids are required for active transport, several enzymatic activities and membrane formation.
Membrane Potentials
The voltage differences across a membrane. For cellular membranes they are computed by subtracting the voltage measured outside the membrane from the voltage measured inside the membrane. They result from differences of inside versus outside concentration of potassium, sodium, chloride, and other ions across cells' or ORGANELLES membranes. For excitable cells, the resting membrane potentials range between -30 and -100 millivolts. Physical, chemical, or electrical stimuli can make a membrane potential more negative (hyperpolarization), or less negative (depolarization).
Membranes, Artificial
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)
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)
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.
Cell Membrane Permeability
A quality of cell membranes which permits the passage of solvents and solutes into and out of cells.
Erythrocyte Membrane
Membrane Fluidity
The motion of phospholipid molecules within the lipid bilayer, dependent on the classes of phospholipids present, their fatty acid composition and degree of unsaturation of the acyl chains, the cholesterol concentration, and temperature.
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)
Cell Fractionation
Techniques to partition various components of the cell into SUBCELLULAR FRACTIONS.
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.
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.
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.)
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.
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.
Brefeldin A
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.
Basement Membrane
A darkly stained mat-like EXTRACELLULAR MATRIX (ECM) that separates cell layers, such as EPITHELIUM from ENDOTHELIUM or a layer of CONNECTIVE TISSUE. The ECM layer that supports an overlying EPITHELIUM or ENDOTHELIUM is called basal lamina. Basement membrane (BM) can be formed by the fusion of either two adjacent basal laminae or a basal lamina with an adjacent reticular lamina of connective tissue. BM, composed mainly of TYPE IV COLLAGEN; glycoprotein LAMININ; and PROTEOGLYCAN, provides barriers as well as channels between interacting cell layers.
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.
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.-.
Carrier Proteins
Endocytosis
Cellular uptake of extracellular materials within membrane-limited vacuoles or microvesicles. ENDOSOMES play a central role in endocytosis.
Transport Vesicles
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.
Membrane Proteins
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.
Lipid Bilayers
Layers of lipid molecules which are two molecules thick. Bilayer systems are frequently studied as models of biological membranes.
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.
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.
Microscopy, Fluorescence
Monosaccharide Transport Proteins
Endosomes
Calcium
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.
Munc18 Proteins
A family of proteins involved in intracellular membrane trafficking. They interact with SYNTAXINS and play important roles in vesicular docking and fusion during EXOCYTOSIS. Their name derives from the fact that they are related to Unc-18 protein, C elegans.
Exocytosis
Cellular release of material within membrane-limited vesicles by fusion of the vesicles with the CELL MEMBRANE.
Microscopy, Confocal
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.
Liposomes
Artificial, single or multilaminar vesicles (made from lecithins or other lipids) that are used for the delivery of a variety of biological molecules or molecular complexes to cells, for example, drug delivery and gene transfer. They are also used to study membranes and membrane proteins.
Models, Biological
Membrane Fusion
R-SNARE Proteins
SNARE proteins where the central amino acid residue of the SNARE motif is an ARGININE. They are classified separately from the Q-SNARE PROTEINS where the central amino acid residue of the SNARE motif is a GLUTAMINE. This subfamily contains the vesicle associated membrane proteins (VAMPs) based on similarity to the prototype for the R-SNAREs, VAMP2 (synaptobrevin 2).
Green Fluorescent Proteins
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.
Cricetinae
Detergents
Vacuoles
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)
Mutation
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.
Nodaviridae
Cells, Cultured
Cytoplasmic Vesicles
Glucose Transporter Type 4
A glucose transport protein found in mature MUSCLE CELLS and ADIPOCYTES. It promotes transport of glucose from the BLOOD into target TISSUES. The inactive form of the protein is localized in CYTOPLASMIC VESICLES. In response to INSULIN, it is translocated to the PLASMA MEMBRANE where it facilitates glucose uptake.
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).)
Syntaxin 1
A neuronal cell membrane protein that combines with SNAP-25 and SYNAPTOBREVIN 2 to form a SNARE complex that leads to EXOCYTOSIS.
Electrophoresis, Polyacrylamide Gel
Freeze Fracturing
Preparation for electron microscopy of minute replicas of exposed surfaces of the cell which have been ruptured in the frozen state. The specimen is frozen, then cleaved under high vacuum at the same temperature. The exposed surface is shadowed with carbon and platinum and coated with carbon to obtain a carbon replica.
Cytosol
Intracellular fluid from the cytoplasm after removal of ORGANELLES and other insoluble cytoplasmic components.
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)
Octoxynol
Nonionic surfactant mixtures varying in the number of repeating ethoxy (oxy-1,2-ethanediyl) groups. They are used as detergents, emulsifiers, wetting agents, defoaming agents, etc. Octoxynol-9, the compound with 9 repeating ethoxy groups, is a spermatocide.
Cell Compartmentation
A partitioning within cells due to the selectively permeable membranes which enclose each of the separate parts, e.g., mitochondria, lysosomes, etc.
Transfection
Microscopy, Immunoelectron
Mitochondrial Membranes
The two lipoprotein layers in the MITOCHONDRION. The outer membrane encloses the entire mitochondrion and contains channels with TRANSPORT PROTEINS to move molecules and ions in and out of the organelle. The inner membrane folds into cristae and contains many ENZYMES important to cell METABOLISM and energy production (MITOCHONDRIAL ATP SYNTHASE).
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)
Hydrogen-Ion Concentration
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)
Luminescent Proteins
Fluorescent Dyes
Qc-SNARE Proteins
A subfamily of Q-SNARE PROTEINS which occupy the same position in the SNARE complex as the C-terminal SNARE domain of SNAP-25 and which also are most similar to the C-terminal region of SNAP-25 in their AMINO ACID SEQUENCE.
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.
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.
Phosphatidylcholines
Derivatives of phosphatidic acids in which the phosphoric acid is bound in ester linkage to a choline moiety. Complete hydrolysis yields 1 mole of glycerol, phosphoric acid and choline and 2 moles of fatty acids.
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.
Blood Platelets
Biological Transport, Active
The movement of materials across cell membranes and epithelial layers against an electrochemical gradient, requiring the expenditure of metabolic energy.
Synaptic Membranes
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.
Cercopithecus aethiops
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.
Binding Sites
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).
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 3.6.1.47
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.
Base Sequence
Nerve Tissue Proteins
'Nerve tissue proteins' are specialized proteins found within the nervous system's biological tissue, including neurofilaments, neuronal cytoskeletal proteins, and neural cell adhesion molecules, which facilitate structural support, intracellular communication, and synaptic connectivity essential for proper neurological function.
Cloning, Molecular
Rabbits
Immunoblotting
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.
Synaptosomal-Associated Protein 25
A ubiquitous target SNARE protein that interacts with SYNTAXIN and SYNAPTOBREVIN. It is a core component of the machinery for intracellular MEMBRANE FUSION. The sequence contains 2 SNARE domains, one is the prototype for the Qb-SNARES, and the other is the prototype for the Qc-SNARES.
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.
Models, Molecular
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.
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.
Qb-SNARE Proteins
A subfamily of Q-SNARE PROTEINS which occupy the same position in the SNARE complex as the N-terminal SNARE domain of SNAP-25 and which also are most similar to the N-terminal region of SNAP-25 in their AMINO ACID SEQUENCE.
Myristic Acid
Protein Structure, Secondary
The level of protein structure in which regular hydrogen-bond interactions within contiguous stretches of polypeptide chain give rise to alpha helices, beta strands (which align to form beta sheets) or other types of coils. This is the first folding level of protein conformation.
Solubility
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.-.
Centrifugation, Density Gradient
Muscle Proteins
Cattle
rab5 GTP-Binding Proteins
A genetically related subfamily of RAB GTP-BINDING PROTEINS involved in transport from the cell membrane to early endosomes. This enzyme was formerly listed as EC 3.6.1.47.
Cholesterol
Glycoproteins
Conjugated protein-carbohydrate compounds including mucins, mucoid, and amyloid glycoproteins.
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.
Extraembryonic Membranes
The thin layers of tissue that surround the developing embryo. There are four extra-embryonic membranes commonly found in VERTEBRATES, such as REPTILES; BIRDS; and MAMMALS. They are the YOLK SAC, the ALLANTOIS, the AMNION, and the CHORION. These membranes provide protection and means to transport nutrients and wastes.
Precipitin Tests
ADP-Ribosylation Factor 1
Virus Replication
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.
Saccharomyces cerevisiae
Nuclear Envelope
RNA Replicase
Vacuolar Proton-Translocating ATPases
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.
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 3.4.12.1 and EC 3.4.21.13.
Sodium-Potassium-Exchanging ATPase
An enzyme that catalyzes the active transport system of sodium and potassium ions across the cell wall. Sodium and potassium ions are closely coupled with membrane ATPase which undergoes phosphorylation and dephosphorylation, thereby providing energy for transport of these ions against concentration gradients.
Actins
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.
Vesicle-Associated Membrane Protein 3
A member of the vesicle associated membrane protein family. It has a broad tissue distribution and is involved in MEMBRANE FUSION events of the endocytic pathways.
Insulin
A 51-amino acid pancreatic hormone that plays a major role in the regulation of glucose metabolism, directly by suppressing endogenous glucose production (GLYCOGENOLYSIS; GLUCONEOGENESIS) and indirectly by suppressing GLUCAGON secretion and LIPOLYSIS. Native insulin is a globular protein comprised of a zinc-coordinated hexamer. Each insulin monomer containing two chains, A (21 residues) and B (30 residues), linked by two disulfide bonds. Insulin is used as a drug to control insulin-dependent diabetes mellitus (DIABETES MELLITUS, TYPE 1).
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.
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.
DNA, Complementary
3T3 Cells
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.
Kidney
Mutagenesis, Site-Directed
Genetically engineered MUTAGENESIS at a specific site in the DNA molecule that introduces a base substitution, or an insertion or deletion.
Cytoskeleton
The network of filaments, tubules, and interconnecting filamentous bridges which give shape, structure, and organization to the cytoplasm.
Soluble N-Ethylmaleimide-Sensitive Factor Attachment Proteins
SNARE binding proteins that facilitate the ATP hydrolysis-driven dissociation of the SNARE complex. They are required for the binding of N-ETHYLMALEIMIDE-SENSITIVE PROTEIN (NSF) to the SNARE complex which also stimulates the ATPASE activity of NSF. They are unrelated structurally to SNAP-25 PROTEIN.
Lipids
A generic term for fats and lipoids, the alcohol-ether-soluble constituents of protoplasm, which are insoluble in water. They comprise the fats, fatty oils, essential oils, waxes, phospholipids, glycolipids, sulfolipids, aminolipids, chromolipids (lipochromes), and fatty acids. (Grant & Hackh's Chemical Dictionary, 5th ed)
Rats, Sprague-Dawley
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.
Amino Acid Motifs
Commonly observed structural components of proteins formed by simple combinations of adjacent secondary structures. A commonly observed structure may be composed of a CONSERVED SEQUENCE which can be represented by a CONSENSUS SEQUENCE.
Receptors, Cell Surface
Cell surface proteins that bind signalling molecules external to the cell with high affinity and convert this extracellular event into one or more intracellular signals that alter the behavior of the target cell (From Alberts, Molecular Biology of the Cell, 2nd ed, pp693-5). Cell surface receptors, unlike enzymes, do not chemically alter their ligands.
Calcium-Transporting ATPases
Dogs
Phosphatidylinositol Phosphates
Phosphoproteins
Phosphoproteins are proteins that have been post-translationally modified with the addition of a phosphate group, usually on serine, threonine or tyrosine residues, which can play a role in their regulation, function, interaction with other molecules, and localization within the cell.
Enzyme Activation
Immunohistochemistry
Fatty Acids
Organic, monobasic acids derived from hydrocarbons by the equivalent of oxidation of a methyl group to an alcohol, aldehyde, and then acid. Fatty acids are saturated and unsaturated (FATTY ACIDS, UNSATURATED). (Grant & Hackh's Chemical Dictionary, 5th ed)
Liver
Neurons
Rats, Inbred Strains
Peptide Fragments
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.
Mutagenesis
Process of generating a genetic MUTATION. It may occur spontaneously or be induced by MUTAGENS.
Cell Membrane Structures
Structures which are part of the CELL MEMBRANE or have cell membrane as a major part of their structure.
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.
Structure-Activity Relationship
Microvilli
Minute projections of cell membranes which greatly increase the surface area of the cell.
Glycosylation
Gene Expression
Microscopy, Electron, Transmission
Fibroblasts
Plasmids
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.
Protein Isoforms
Glucose Transporter Type 1
A ubiquitously expressed glucose transporter that is important for constitutive, basal GLUCOSE transport. It is predominately expressed in ENDOTHELIAL CELLS and ERYTHROCYTES at the BLOOD-BRAIN BARRIER and is responsible for GLUCOSE entry into the BRAIN.
Viral Nonstructural Proteins
Proteins encoded by a VIRAL GENOME that are produced in the organisms they infect, but not packaged into the VIRUS PARTICLES. Some of these proteins may play roles within the infected cell during VIRUS REPLICATION or act in regulation of virus replication or VIRUS ASSEMBLY.
Lipid Metabolism
Physiological processes in biosynthesis (anabolism) and degradation (catabolism) of LIPIDS.
Electrophoresis
Erythrocytes
Red blood cells. Mature erythrocytes are non-nucleated, biconcave disks containing HEMOGLOBIN whose function is to transport OXYGEN.
Adipocytes
Cells in the body that store FATS, usually in the form of TRIGLYCERIDES. WHITE ADIPOCYTES are the predominant type and found mostly in the abdominal cavity and subcutaneous tissue. BROWN ADIPOCYTES are thermogenic cells that can be found in newborns of some species and hibernating mammals.
PC12 Cells
A CELL LINE derived from a PHEOCHROMOCYTOMA of the rat ADRENAL MEDULLA. PC12 cells stop dividing and undergo terminal differentiation when treated with NERVE GROWTH FACTOR, making the line a useful model system for NERVE CELL differentiation.
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)
Group IV Phospholipases A2
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.
Membrane Potential, Mitochondrial
The voltage difference, normally maintained at approximately -180mV, across the INNER MITOCHONDRIAL MEMBRANE, by a net movement of positive charge across the membrane. It is a major component of the PROTON MOTIVE FORCE in MITOCHONDRIA used to drive the synthesis of ATP.
Purple Membrane
Functionally and structurally differentiated, purple-pigmented regions of the cytoplasmic membrane of some strains of Halobacterium halobium. The membrane develops under anaerobic conditions and is made almost entirely of the purple pigment BACTERIORHODOPSINS. (From Singleton & Sainsbury Dictionary of Microbiology and Molecular Biology, 2d ed)
Ion Channels
Gated, ion-selective glycoproteins that traverse membranes. The stimulus for ION CHANNEL GATING can be due to a variety of stimuli such as LIGANDS, a TRANSMEMBRANE POTENTIAL DIFFERENCE, mechanical deformation or through INTRACELLULAR SIGNALING PEPTIDES AND PROTEINS.
Sodium
Antigens, Surface
Antigens on surfaces of cells, including infectious or foreign cells or viruses. They are usually protein-containing groups on cell membranes or walls and may be isolated.
Phospholipids
Lipids containing one or more phosphate groups, particularly those derived from either glycerol (phosphoglycerides see GLYCEROPHOSPHOLIPIDS) or sphingosine (SPHINGOLIPIDS). They are polar lipids that are of great importance for the structure and function of cell membranes and are the most abundant of membrane lipids, although not stored in large amounts in the system.
Protein Precursors
Protein precursors, also known as proproteins or prohormones, are inactive forms of proteins that undergo post-translational modification, such as cleavage, to produce the active functional protein or peptide hormone.
NADH Dehydrogenase
A flavoprotein and iron sulfur-containing oxidoreductase that catalyzes the oxidation of NADH to NAD. In eukaryotes the enzyme can be found as a component of mitochondrial electron transport complex I. Under experimental conditions the enzyme can use CYTOCHROME C GROUP as the reducing cofactor. The enzyme was formerly listed as EC 1.6.2.1.
Tissue Distribution
Accumulation of a drug or chemical substance in various organs (including those not relevant to its pharmacologic or therapeutic action). This distribution depends on the blood flow or perfusion rate of the organ, the ability of the drug to penetrate organ membranes, tissue specificity, protein binding. The distribution is usually expressed as tissue to plasma ratios.
Chloride Channels
Cell membrane glycoproteins that form channels to selectively pass chloride ions. Nonselective blockers include FENAMATES; ETHACRYNIC ACID; and TAMOXIFEN.
Multiprotein Complexes
Tumor Cells, Cultured
Cells grown in vitro from neoplastic tissue. If they can be established as a TUMOR CELL LINE, they can be propagated in cell culture indefinitely.