Association of IRS-1 with the insulin receptor and the phosphatidylinositol 3'-kinase. Formation of binary and ternary signaling complexes in intact cells.
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 alpha IR immunoprecipitates, and IRS-1 markedly increases the in vitro binding of p85 alpha 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.
Joslin Diabetes Center, Department of Medicine, Brigham and Women's Hospital, Boston Massachusetts 02215.
J M
JM
Backer
M G
MG
Myers
X J
XJ
Sun
D J
DJ
Chin
S E
SE
Shoelson
M
M
Miralpeix
M F
MF
White
D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies; D016466:CHO Cells; D002462:Cell Membrane / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D002855:Chromatography, Thin Layer; D006224:Cricetinae; D006801:Humans; D007295:Inositol Phosphates / Q000302:isolation & purification / Q000378:metabolism; D007328:Insulin / Q000494:pharmacology*; D055504:Insulin Receptor Substrate Proteins; D008954:Models, Biological; D008969:Molecular Sequence Data; D010455:Peptides / Q000138:chemical synthesis / Q000276:immunology; D019869:Phosphatidylinositol 3-Kinases; D010748:Phosphopeptides / Q000138:chemical synthesis; D010750:Phosphoproteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D010770:Phosphotransferases / Q000302:isolation & purification / Q000378:metabolism*; D011972:Receptor, Insulin / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D014162:Transfection
D000906:Antibodies; C526292:IRS1 protein, human; D007295:Inositol Phosphates; D007328:Insulin; D055504:Insulin Receptor Substrate Proteins; D010455:Peptides; D010748:Phosphopeptides; D010750:Phosphoproteins; D011994:Recombinant Proteins; D010770:Phosphotransferases; D019869:Phosphatidylinositol 3-Kinases; D011972:Receptor, Insulin