Abstract
Insulin stimulates the formation of binary and ternary signaling complexes between the phosphatidylinositol (PtdIns) 3′-kinase, IRS-1, and the insulin receptor in vivo. Binary complex formation between IRS-1 and the PtdIns 3′-kinase occurs in intact cells and requires the tyrosyl phosphorylation IRS-1, as mutant insulin receptors which weakly phosphorylate IRS-1 in vivo do not mediate formation of IRS-1/ PtdIns 3′-kinase complexes in transfected CHO cells. Association with IRS-1 involves as much as 70% of total cellular PtdIns 3′-kinase activity. Insulin also stimulates the formation of ternary signaling complexes, as both IRS-1 and the PtdIns 3′-kinase are present in anti-insulin receptor immunoprecipitates from insulin-stimulated cells. Overexpression of IRS-1 in CHO cells increases the amount of PtdIns 3′-kinase activity in αIR immunoprecipitates, and IRS-1 markedly increases the in vitro binding of p85α and PtdIns 3-kinase activity to anti-receptor immunoprecipitates. The mechanism for this association is unknown, but appears to involve the binding of IRS-1/PtdIns 3′-kinase complexes to the insulin receptor. The formation of binary and ternary complexes between the insulin receptor, IRS-1 and the PtdIns 3′-kinase may play a critical role in transmission of the insulin signal.
Original language | English (US) |
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Pages (from-to) | 8204-8212 |
Number of pages | 9 |
Journal | Journal of Biological Chemistry |
Volume | 268 |
Issue number | 11 |
State | Published - Apr 15 1993 |
ASJC Scopus subject areas
- Biochemistry
- Molecular Biology
- Cell Biology