title: Metal: ATP characteristics of insulin- and epidermal growth factor-stimulated phosphorylation in detergent extracts of rat liver plasma membranes.
abstract: The metal: ATP characteristics of insulin- and epidermal growth factor-(EGF)-stimulated protein kinase activities were examined in Nonidet P40 extracts of rat liver plasma membranes. The two kinase activities were capable of utilizing either manganese or magnesium, although differences were observed. Insulin-stimulated 32P incorporation into an Mr 95 000 protein exhibited a higher affinity for ATP in the presence of manganese compared to magnesium. At 200 microM ATP, insulin stimulated 32P incorporation into the Mr 95 000 protein 3- to 5-fold after 5 min in the presence of either metal. At 1 mM ATP, insulin-stimulated 32P incorporation was significantly greater in the presence of magnesium. In contrast, EGF-stimulated 32P incorporation into an Mr 170 000 protein exhibited similar ATP dependencies in the presence of magnesium or manganese. Basal phosphorylation of the Mr 170 000 protein was 2- to 3-fold higher in the presence of manganese, however. Since the higher basal phosphorylation persisted after chromatography on wheat germ lectin-Sepharose, it may represent an inherent activity of the receptor kinase. In the presence of magnesium: ATP, low concentrations of manganese enhanced both insulin- and EGF-stimulated phosphorylation of angiotensin II suggesting involvement of a second metal binding site which regulates the kinase activity. The results presented show major differences in the metal: ATP properties of the two major hormonally regulated protein kinase activities observed in detergent-extracted liver membranes.
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D002462:Cell Membrane / Q000187:drug effects / Q000201:enzymology; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D007328:Insulin / Q000494:pharmacology*; D008099:Liver / Q000187:drug effects / Q000201:enzymology*; D008274:Magnesium / Q000494:pharmacology*; D008345:Manganese / Q000494:pharmacology*; D008970:Molecular Weight; D017830:Octoxynol; D010766:Phosphorylation; D011092:Polyethylene Glycols / Q000494:pharmacology*; D011494:Protein Kinases / Q000378:metabolism; D051381:Rats
chemical_list: D007328:Insulin; D000804:Angiotensin II; D011092:Polyethylene Glycols; D008345:Manganese; D004815:Epidermal Growth Factor; D000255:Adenosine Triphosphate; D017830:Octoxynol; C010615:Nonidet P-40; D011494:Protein Kinases; D008274:Magnesium