title: Insulin stimulation of phosphorylation of the beta subunit of the insulin receptor. Formation of both phosphoserine and phosphotyrosine.
abstract: Rat hepatoma cells were labeled with [32P]orthophosphate and the insulin receptor subunits were identified by immunoprecipitation and sodium dodecyl sulfate-acrylamide gel electrophoresis. In the basal state, only the Mr = 95,000 (beta) subunit of the insulin receptor was phosphorylated. The covalent labeling with 32P of this subunit was stimulated about 3-fold by insulin (10(-6) M). This stimulation was due to an increase in the content of phosphoserine, the appearance of phosphotyrosine, and a possible increase in phosphothreonine as well. These results suggest phosphorylation of the insulin receptor at multiple sites is an early event in insulin action.
mesh_terms: D000596:Amino Acids / Q000302:isolation & purification; D000818:Animals; D007328:Insulin / Q000494:pharmacology*; D008114:Liver Neoplasms, Experimental / Q000378:metabolism; D046911:Macromolecular Substances; D008970:Molecular Weight; D010766:Phosphorylation; D010768:Phosphoserine / Q000096:biosynthesis*; D019000:Phosphotyrosine; D051381:Rats; D011972:Receptor, Insulin / Q000187:drug effects / Q000378:metabolism*; D012694:Serine / Q000031:analogs & derivatives*; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000096:biosynthesis
chemical_list: D000596:Amino Acids; D007328:Insulin; D046911:Macromolecular Substances; D010768:Phosphoserine; D019000:Phosphotyrosine; D014443:Tyrosine; D012694:Serine; D011972:Receptor, Insulin