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Identification of the insulin receptor tyrosine residues undergoing insulin-stimulated phosphorylation in intact rat hepatoma cells

Journal Article · · J. Biol. Chem.; (United States)
OSTI ID:6837967
Tyr(P)-containing proteins were purified from extracts of insulin-treated rat hepatoma cells (H4-II-E-C3) by antiphosphotyrosine immunoaffinity chromatography. Two major insulin-stimulated, Tyr(P) proteins were recovered: an M/sub r/ 95,000 protein (identified as the insulin receptor ..beta.. subunit by its immunoprecipitation by a patient-derived anti-insulin receptor serum and several anti-insulin receptor (peptide) anti-sera) and an M/sub r/ 180,000 protein. After purification and tryptic digestion of the M/sub r/ 95,000 protein, tryptic peptides containing Tyr (P) were purified by sequential antiphosphotyrosine immunoaffinity, reversed-phase, anion-exchange chromatography. Approximately 80% of all ..beta.. subunit (/sup 32/P)Tyr(P) resides on two tryptic peptides: 50-60% of (/sup 32/P)Tyr(P) is found on the tryptic peptide Asp-Ile-Try-Glu-Thr-Asp-Try-Try-Arg from the tyrosine kinase domain. A second tryptic peptide is located near the carboxyl terminus; this contains 20-30% of ..beta.. subunit (/sup 32/P)Tyr(P) and is identified primarily in a double phosphorylated form. In a summary, the insulin-stimulated tyrosine phosphorylation of the insulin receptor in intact rat hepatoma cells involves at least 6 of the 13 tyrosine residues located on the ..beta.. subunit intracellular extension. These tyrosines are clustered in several domains in a distribution virtually identical to that previously found for partially purified human insulin receptor autophosphorylated in vitro in the presence of insulin.
Research Organization:
Harvard Medical School, Boston, MA (USA)
OSTI ID:
6837967
Journal Information:
J. Biol. Chem.; (United States), Journal Name: J. Biol. Chem.; (United States) Vol. 263:1; ISSN JBCHA
Country of Publication:
United States
Language:
English