Insulin Receptor Substrate Proteins
A structurally-related group of signaling proteins that are phosphorylated by the INSULIN RECEPTOR PROTEIN-TYROSINE KINASE. The proteins share in common an N-terminal PHOSPHOLIPID-binding domain, a phosphotyrosine-binding domain that interacts with the phosphorylated INSULIN RECEPTOR, and a C-terminal TYROSINE-rich domain. Upon tyrosine phosphorylation insulin receptor substrate proteins interact with specific SH2 DOMAIN-containing proteins that are involved in insulin receptor signaling.
Phosphoproteins
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).
Receptor, Insulin
A cell surface receptor for INSULIN. It comprises a tetramer of two alpha and two beta subunits which are derived from cleavage of a single precursor protein. The receptor contains an intrinsic TYROSINE KINASE domain that is located within the beta subunit. Activation of the receptor by INSULIN results in numerous metabolic changes including increased uptake of GLUCOSE into the liver, muscle, and ADIPOSE TISSUE.
Phosphorylation
Phosphatidylinositol 3-Kinases
Phosphotransferases that catalyzes the conversion of 1-phosphatidylinositol to 1-phosphatidylinositol 3-phosphate. Many members of this enzyme class are involved in RECEPTOR MEDIATED SIGNAL TRANSDUCTION and regulation of vesicular transport with the cell. Phosphatidylinositol 3-Kinases have been classified both according to their substrate specificity and their mode of action within the cell.
Insulin Resistance
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.
Intracellular Signaling Peptides and Proteins
Proteins and peptides that are involved in SIGNAL TRANSDUCTION within the cell. Included here are peptides and proteins that regulate the activity of TRANSCRIPTION FACTORS and cellular processes in response to signals from CELL SURFACE RECEPTORS. Intracellular signaling peptide and proteins may be part of an enzymatic signaling cascade or act through binding to and modifying the action of other signaling factors.
Glucose
Tyrosine
Receptor, IGF Type 1
A protein-tyrosine kinase receptor that is closely related in structure to the INSULIN RECEPTOR. Although commonly referred to as the IGF-I receptor, it binds both IGF-I and IGF-II with high affinity. It is comprised of a tetramer of two alpha and two beta subunits which are derived from cleavage of a single precursor protein. The beta subunit contains an intrinsic tyrosine kinase domain.
Proto-Oncogene Proteins c-akt
A protein-serine-threonine kinase that is activated by PHOSPHORYLATION in response to GROWTH FACTORS or INSULIN. It plays a major role in cell metabolism, growth, and survival as a core component of SIGNAL TRANSDUCTION. Three isoforms have been described in mammalian cells.
Phosphotyrosine
An amino acid that occurs in endogenous proteins. Tyrosine phosphorylation and dephosphorylation plays a role in cellular signal transduction and possibly in cell growth control and carcinogenesis.
Substrate Specificity
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.
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.
Insulin-Like Growth Factor I
A well-characterized basic peptide believed to be secreted by the liver and to circulate in the blood. It has growth-regulating, insulin-like, and mitogenic activities. This growth factor has a major, but not absolute, dependence on GROWTH HORMONE. It is believed to be mainly active in adults in contrast to INSULIN-LIKE GROWTH FACTOR II, which is a major fetal growth factor.
Phosphotransferases (Alcohol Group Acceptor)
Enzyme Activation
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.
Muscle, Skeletal
Adaptor Proteins, Signal Transducing
A broad category of carrier proteins that play a role in SIGNAL TRANSDUCTION. They generally contain several modular domains, each of which having its own binding activity, and act by forming complexes with other intracellular-signaling molecules. Signal-transducing adaptor proteins lack enzyme activity, however their activity can be modulated by other signal-transducing enzymes
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.
Chaperonin 10
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.
Monosaccharide Transport Proteins
A large group of membrane transport proteins that shuttle MONOSACCHARIDES across CELL MEMBRANES.
Protein-Serine-Threonine Kinases
A group of enzymes that catalyzes the phosphorylation of serine or threonine residues in proteins, with ATP or other nucleotides as phosphate donors.
Protein-Tyrosine Kinases
Protein kinases that catalyze the PHOSPHORYLATION of TYROSINE residues in proteins with ATP or other nucleotides as phosphate donors.
Deoxyglucose
2-Deoxy-D-arabino-hexose. An antimetabolite of glucose with antiviral activity.
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.
GRB2 Adaptor Protein
A signal transducing adaptor protein that links extracellular signals to the MAP KINASE SIGNALING SYSTEM. Grb2 associates with activated EPIDERMAL GROWTH FACTOR RECEPTOR and PLATELET-DERIVED GROWTH FACTOR RECEPTORS via its SH2 DOMAIN. It also binds to and translocates the SON OF SEVENLESS PROTEINS through its SH3 DOMAINS to activate PROTO-ONCOGENE PROTEIN P21(RAS).
Insulin Antagonists
Compounds which inhibit or antagonize the biosynthesis or action of insulin.
Liver
Hypoglycemic Agents
Substances which lower blood glucose levels.
Serine
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.
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.
Adipose Tissue
Specialized connective tissue composed of fat cells (ADIPOCYTES). It is the site of stored FATS, usually in the form of TRIGLYCERIDES. In mammals, there are two types of adipose tissue, the WHITE FAT and the BROWN FAT. Their relative distributions vary in different species with most adipose tissue being white.
Binding Sites
Chaperonin 60
A group I chaperonin protein that forms the barrel-like structure of the chaperonin complex. It is an oligomeric protein with a distinctive structure of fourteen subunits, arranged in two rings of seven subunits each. The protein was originally studied in BACTERIA where it is commonly referred to as GroEL protein.
Proto-Oncogene Proteins
Diabetes Mellitus, Type 2
A subclass of DIABETES MELLITUS that is not INSULIN-responsive or dependent (NIDDM). It is characterized initially by INSULIN RESISTANCE and HYPERINSULINEMIA; and eventually by GLUCOSE INTOLERANCE; HYPERGLYCEMIA; and overt diabetes. Type II diabetes mellitus is no longer considered a disease exclusively found in adults. Patients seldom develop KETOSIS but often exhibit OBESITY.
Cells, Cultured
Islets of Langerhans
Irregular microscopic structures consisting of cords of endocrine cells that are scattered throughout the PANCREAS among the exocrine acini. Each islet is surrounded by connective tissue fibers and penetrated by a network of capillaries. There are four major cell types. The most abundant beta cells (50-80%) secrete INSULIN. Alpha cells (5-20%) secrete GLUCAGON. PP cells (10-35%) secrete PANCREATIC POLYPEPTIDE. Delta cells (~5%) secrete SOMATOSTATIN.
Cricetinae
Protein Tyrosine Phosphatases
An enzyme group that specifically dephosphorylates phosphotyrosyl residues in selected proteins. Together with PROTEIN-TYROSINE KINASE, it regulates tyrosine phosphorylation and dephosphorylation in cellular signal transduction and may play a role in cell growth control and carcinogenesis.
Precipitin Tests
Ribosomal Protein S6 Kinases
A family of protein serine/threonine kinases which act as intracellular signalling intermediates. Ribosomal protein S6 kinases are activated through phosphorylation in response to a variety of HORMONES and INTERCELLULAR SIGNALING PEPTIDES AND PROTEINS. Phosphorylation of RIBOSOMAL PROTEIN S6 by enzymes in this class results in increased expression of 5' top MRNAs. Although specific for RIBOSOMAL PROTEIN S6 members of this class of kinases can act on a number of substrates within the cell. The immunosuppressant SIROLIMUS inhibits the activation of ribosomal protein S6 kinases.
Androstadienes
Mice, Knockout
Strains of mice in which certain GENES of their GENOMES have been disrupted, or "knocked-out". To produce knockouts, using RECOMBINANT DNA technology, the normal DNA sequence of the gene being studied is altered to prevent synthesis of a normal gene product. Cloned cells in which this DNA alteration is successful are then injected into mouse EMBRYOS to produce chimeric mice. The chimeric mice are then bred to yield a strain in which all the cells of the mouse contain the disrupted gene. Knockout mice are used as EXPERIMENTAL ANIMAL MODELS for diseases (DISEASE MODELS, ANIMAL) and to clarify the functions of the genes.
Protein Tyrosine Phosphatase, Non-Receptor Type 1
A subtype of non-receptor protein tyrosine phosphatases that includes two distinctive targeting motifs; an N-terminal motif specific for the INSULIN RECEPTOR, and a C-terminal motif specific for the SH3 domain containing proteins. This subtype includes a hydrophobic domain which localizes it to the ENDOPLASMIC RETICULUM.
Hyperinsulinism
A syndrome with excessively high INSULIN levels in the BLOOD. It may cause HYPOGLYCEMIA. Etiology of hyperinsulinism varies, including hypersecretion of a beta cell tumor (INSULINOMA); autoantibodies against insulin (INSULIN ANTIBODIES); defective insulin receptor (INSULIN RESISTANCE); or overuse of exogenous insulin or HYPOGLYCEMIC AGENTS.
Transfection
Muscle Proteins
The protein constituents of muscle, the major ones being ACTINS and MYOSINS. More than a dozen accessory proteins exist including TROPONIN; TROPOMYOSIN; and DYSTROPHIN.
Phosphoserine
The phosphoric acid ester of serine.
Glucose Tolerance Test
A test to determine the ability of an individual to maintain HOMEOSTASIS of BLOOD GLUCOSE. It includes measuring blood glucose levels in a fasting state, and at prescribed intervals before and after oral glucose intake (75 or 100 g) or intravenous infusion (0.5 g/kg).
src Homology Domains
Regions of AMINO ACID SEQUENCE similarity in the SRC-FAMILY TYROSINE KINASES that fold into specific functional tertiary structures. The SH1 domain is a CATALYTIC DOMAIN. SH2 and SH3 domains are protein interaction domains. SH2 usually binds PHOSPHOTYROSINE-containing proteins and SH3 interacts with CYTOSKELETAL PROTEINS.
Protein Tyrosine Phosphatase, Non-Receptor Type 11
A subtype of non-receptor protein tyrosine phosphatases that contain two SRC HOMOLOGY DOMAINS. Mutations in the gene for protein tyrosine phosphatase, non-receptor type 11 are associated with NOONAN SYNDROME.