title: Characterization of the phosphorylated intermediate of the isolated high-affinity (Ca2+ + Mg2+)-ATPase of human erythrocyte membranes.
abstract: Phosphorylation of solubilized and purified high-affinity (Ca2+ + Mg2+)-ATPase (ATP phosphohydrolase, EC 3.6.1.3) of human erythrocyte membranes shows no dependence on cyclic AMP concentration in the range 0.1--1000 microM. Ca2+-dependent phosphoprotein is sensitive to hydroxylamine and molybdate treatment. The phosphate linkage shows maximum stability at low pH values, which is progressively lost as the pH rises, with a shoulder around pH 6. SDS gel electrophoresis of the phosphorylated protein yields a peak which shows relative mobility corresponding to a molecular weight of 145 000 and sensitivity to MgATP-chase and hydroxylamine treatment. This indicates that the phosphoprotein represents the phosphorylated intermediate of the high-affinity (Ca2+ + Mg2+)-ATPase of human erythrocyte membranes.
mesh_terms: D017301:Ca(2+) Mg(2+)-ATPase; D000252:Calcium-Transporting ATPases / Q000097:blood*; D000242:Cyclic AMP / Q000494:pharmacology; D004910:Erythrocyte Membrane / Q000201:enzymology*; D004912:Erythrocytes / Q000201:enzymology*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D006898:Hydroxylamines / Q000494:pharmacology*; D007700:Kinetics; D008982:Molybdenum / Q000494:pharmacology; D010766:Phosphorylation; D011494:Protein Kinases / Q000097:blood*
chemical_list: D006898:Hydroxylamines; D008982:Molybdenum; D000242:Cyclic AMP; D011494:Protein Kinases; D017301:Ca(2+) Mg(2+)-ATPase; D000252:Calcium-Transporting ATPases