title: Insulin-like growth factor I binding and receptor kinase in red and white muscle.
abstract: IGF-I receptors were partially purified from red and white skeletal muscle by lectin-affinity chromatography and the resultant fraction was depleted of insulin receptors by insulin affinity chromatography. Equilibrium binding of 125I-IGF-I to receptor preparations from red and white muscle yielded identical Scatchard plots. The integrity of the IGF-I receptor preparation in the two fiber types was identical as determined by affinity cross-linking. The tyrosine kinase activity of the receptor from red muscle was 2-3-fold more active towards exogenous substrates in both the basal and ligand-activated states as compared to white muscle. These data show that there is IGF-I-dependent kinase activity intrinsic to IGF-I receptors from skeletal muscle, and suggest that identical cellular factors may regulate the kinase activity of insulin and IGF-I receptors in a parallel manner in vivo.
authors.affiliation: Department of Biochemistry, Boston University School of Medicine, MA 02118.
authors.forename: A
authors.initials: A
authors.lastname: Zorzano
authors.forename: D E
authors.initials: DE
authors.lastname: James
authors.forename: N B
authors.initials: NB
authors.lastname: Ruderman
authors.forename: P F
authors.initials: PF
authors.lastname: Pilch
mesh_terms: D000818:Animals; D007328:Insulin / Q000494:pharmacology; D007334:Insulin-Like Growth Factor I / Q000378:metabolism* / Q000494:pharmacology; D007700:Kinetics; D008297:Male; D009132:Muscles / Q000378:metabolism*; D009928:Organ Specificity; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D011972:Receptor, Insulin / Q000302:isolation & purification / Q000378:metabolism*; D017451:Receptors, Somatomedin; D013002:Somatomedins / Q000378:metabolism*
chemical_list: D007328:Insulin; D017451:Receptors, Somatomedin; D013002:Somatomedins; D007334:Insulin-Like Growth Factor I; D011505:Protein-Tyrosine Kinases; D011972:Receptor, Insulin