Insulin receptor structural requirements for the formation of a ternary complex with IRS-1 and PI 3-kinase.
Insulin receptor substrate-1 (IRS-1) is a major substrate of the insulin receptor tyrosine kinase and is an intermediate in insulin signaling. Phosphotyrosyl-IRS-1 binds to other signaling proteins including phosphatidylinositol 3-kinase (PI 3-kinase). We examined the role of three insulin receptor tyrosine autophosphorylation domains in association of the receptor with IRS-1. Our data support the idea that tyrosine phosphorylation of the insulin receptor juxtamembrane domain is necessary for receptor association with IRS-1. We provide evidence that the kinase regulatory domain, which is part of a loop structure at the mouth of the catalytic cleft, when mutated to replace Tyr1146, Tyr1150, and Tyr1151 with phenylalanine can bind receptor substrates without tyrosine phosphorylation of residues in the receptor juxtamembrane region. In addition, our data show that the amount of PI 3-kinase directly associated with the insulin receptor C-terminus is low when compared to the PI 3-kinase associating with IRS-1. We also demonstrate that a substantial amount (approximately 25%) of the IRS-1 associated PI 3-kinase is associated with the insulin receptor in a ternary complex of insulin receptor/IRS-1/PI 3-kinase.
Department of Pharmacology, University of Missouri-Columbia, School of Medicine 65212, USA. pharmpaw@muccmail.missouri.edu
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Wilden
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Rovira
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Broadway
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001665:Binding Sites; D016466:CHO Cells; D006224:Cricetinae; D015870:Gene Expression; D007328:Insulin / Q000494:pharmacology; D055504:Insulin Receptor Substrate Proteins; D009154:Mutation; D019869:Phosphatidylinositol 3-Kinases; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism*; D011972:Receptor, Insulin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D013329:Structure-Activity Relationship; D014162:Transfection
D007328:Insulin; D055504:Insulin Receptor Substrate Proteins; D010750:Phosphoproteins; D000255:Adenosine Triphosphate; D019869:Phosphatidylinositol 3-Kinases; D017853:Phosphotransferases (Alcohol Group Acceptor); D011972:Receptor, Insulin