Insulin rapidly stimulates phosphorylation of a 46-kDa membrane protein on tyrosine residues as well as phosphorylation of several soluble proteins in intact fat cells

Journal Article · Thu Jan 01 04:00:00 EST 1987 · Proc. Natl. Acad. Sci. U.S.A.; (United States)

DOI:https://doi.org/10.1073/pnas.84.1.113· OSTI ID:5520453

Haering, H U; White, M F; Machicao, F; Ermel, B; Schleicher, E; Obermaier, B

It is speculated that the transmission of an insulin signal across the plasma membrane of cells occurs through activation of the tyrosine-specific receptor kinase, autophosphorylation of the receptor, and subsequent phosphorylation of unidentified substrates in the cell. In an attempt to identify possible substrates, the authors labeled intact rat fat cells with (/sup 32/P)orthophosphate and used an antiphosphotyrosine antibody to identify proteins that become phosphorylated on tyrosine residues in an insulin-stimulated way. In the membrane fraction of the fat cells, they found, in addition to the 95-kDa ..beta..-subunit of the receptor, a 46-kDa phosphoprotein that is phosphorylated exclusively on tyrosine residues. This protein is not immunoprecipitated by antibodies against different regions of the insulin receptor and its HPLC tryptic peptide map is different from the tryptic peptide map of the insulin receptor, suggesting that it is not derived from the receptor ..beta..-subunit. Insulin stimulates the tyrosine phosphorylation of the 46-kDa protein within 150 sec in the intact cell 3- to 4-fold in a dose-dependent way at insulin concentrations between 0.5 nM and 100 nM. Insulin (0.5 nM, 100 nM) stimulated within 2 min the /sup 32/P incorporation into a 116-kDa band, a 62 kDa band, and three bands between 45 kDa and 50 kDa 2- to 10-fold. They suggest that the 46-kDa membrane protein and possibly also the soluble proteins are endogenous substrates of the receptor tyrosine kinase in fat cells and that their phosphorylation is an early step in insulin signal transmission.

• Research Organization: Institut fuer Diabetesforschung, Munich, Germany, F.R.
• OSTI ID: 5520453
• Journal Information: Proc. Natl. Acad. Sci. U.S.A.; (United States), Journal Name: Proc. Natl. Acad. Sci. U.S.A.; (United States) Vol. 84:1; ISSN PNASA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ADIPOSE TISSUE
AMINO ACIDS
ANIMAL CELLS
ANIMAL TISSUES
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOCHEMISTRY
BODY
CARBOXYLIC ACIDS
CELL CONSTITUENTS
CELL MEMBRANES
CHEMICAL REACTIONS
CHEMISTRY
CONNECTIVE TISSUE
DAYS LIVING RADIOISOTOPES
DOMESTIC ANIMALS
ENZYME INDUCTION
ENZYMES
GENE REGULATION
HORMONES
HYDROXY ACIDS
INSULIN
ISOTOPES
LABELLING
LIGHT NUCLEI
MAMMALS
MEMBRANES
NUCLEI
ODD-ODD NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
PEPTIDE HORMONES
PHOSPHORUS 32
PHOSPHORUS ISOTOPES
PHOSPHORUS-GROUP TRANSFERASES
PHOSPHORYLATION
PHOSPHOTRANSFERASES
PROTEINS
RADIOISOTOPES
RATS
RODENTS
SWINE
TISSUES
TRANSFERASES
TYROSINE
VERTEBRATES