Insulin stimulates the tyrosine dephosphorylation of docking protein p130cas (Crk-associated substrate), promoting the switch of the adaptor protein crk from p130cas to newly phosphorylated insulin receptor substrate-1.
The docking protein p130(cas) (Crk-associated substrate) forms a stable complex with the adaptor protein CrkII in a tyrosine-phosphorylation-dependent manner. Insulin-induced tyrosine phosphorylation of insulin receptor substrates results in the redistribution of CrkII between p130(cas) and insulin receptor substrate-1. A decrease in the association between CrkII and p130(cas) in response to insulin stimulation was detected in CHO cells stably expressing insulin receptor or insulin receptor substrate-1, and in L6 rat myoblasts. Along with the decrease in the association of CrkII with p130(cas), the amount of tyrosine-phosphorylated insulin receptor substrate-1 co-precipitated with CrkII increased in all cell types studied. The insulin-induced decrease in the CrkII-p130(cas) association was further confirmed by Far Western Blot analysis with the Src homology 2 (SH2) domain of CrkII. Insulin regulates the association of CrkII with p130(cas) by tyrosine dephosphorylation of p130(cas) and co-ordinated tyrosine phosphorylation of insulin receptor substrate-1. Tyrosine-phosphorylated insulin receptor substrate-1 serves as a docking protein for multiple adaptor proteins and competes with p130(cas) for CrkII.
Sorokin
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A
Department of Medicine and Cardiovascular Research Center, Medical College of Wisconsin, Milwaukee, WI 53226, USA. sorokin@post.its.mcw.edu
Reed
E
E
D000818:Animals; D001665:Binding Sites; D016466:CHO Cells; D002417:Cattle; D002999:Clone Cells; D006224:Cricetinae; D050719:Crk-Associated Substrate Protein; D006801:Humans; D066298:In Vitro Techniques; D007328:Insulin / Q000494:pharmacology*; D055504:Insulin Receptor Substrate Proteins; D051379:Mice; D010750:Phosphoproteins / Q000737:chemistry* / Q000378:metabolism*; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*; D011506:Proteins; D011518:Proto-Oncogene Proteins; D050737:Proto-Oncogene Proteins c-crk; D051381:Rats; D011972:Receptor, Insulin / Q000378:metabolism*; D050717:Retinoblastoma-Like Protein p130; D014443:Tyrosine / Q000737:chemistry / Q000378:metabolism; D018909:src Homology Domains
C493841:BCAR1 protein, human; C493842:Bcar1 protein, mouse; C493843:Bcar1 protein, rat; C493872:Crk protein, rat; D050719:Crk-Associated Substrate Protein; C526292:IRS1 protein, human; D007328:Insulin; D055504:Insulin Receptor Substrate Proteins; C526295:Irs1 protein, mouse; C526296:Irs1 protein, rat; D010750:Phosphoproteins; D011506:Proteins; D011518:Proto-Oncogene Proteins; D050737:Proto-Oncogene Proteins c-crk; D050717:Retinoblastoma-Like Protein p130; D014443:Tyrosine; D011494:Protein Kinases; D011972:Receptor, Insulin