title: Characterization of skeletal muscle insulin receptor.
abstract: The insulin receptor from rat skeletal muscle was characterized. Treatment of muscle membranes with the photoactive insulin analog, 125I[N-epsilonB29-monoazidobenzoyl]-insulin revealed a single protein band of 135,000 Da, the alpha subunit. Iodination of total membrane protein followed by Triton X-100 solubilization and immunoprecipitation demonstrated the presence of a protein band of 90,000 Da, the beta subunit, together with a protein band of 190,000 Da, which may be the receptor precursor. In partially purified receptor preparations, the beta subunit exhibited dose-dependent, insulin-stimulated phosphorylation with incorporation of phosphate solely into tyrosine residues, which was also observed in the 190,000-Da receptor precursor. Purified plasma membranes contained a large amount of insulin-degrading activity which had to be inactivated prior to performing insulin-binding studies. If degradation of insulin was not prevented, apparent enhanced binding in the presence of unlabeled insulin was observed.
mesh_terms: D000345:Affinity Labels; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D001345:Autoradiography; D001386:Azides; D002462:Cell Membrane / Q000378:metabolism; D055598:Chemical Phenomena; D002621:Chemistry; D002845:Chromatography / Q000379:methods; D007328:Insulin / Q000031:analogs & derivatives; D008297:Male; D008565:Membrane Proteins / Q000032:analysis; D009132:Muscles / Q000378:metabolism*; D010446:Peptide Fragments / Q000032:analysis; D010766:Phosphorylation; D010777:Photochemistry; D051381:Rats; D011919:Rats, Inbred Strains; D011972:Receptor, Insulin / Q000032:analysis*
chemical_list: D000345:Affinity Labels; D000596:Amino Acids; D001386:Azides; D007328:Insulin; D008565:Membrane Proteins; D010446:Peptide Fragments; C025300:insulin, 4-azidobenzoyl(B29)-; D011972:Receptor, Insulin