Characterization of the plasma membrane Mg2+-ATPase from the yeast, Saccharomyces cerevisiae.

摘要: Abstract The plasma membrane of Saccharomyces cerevisiae has a Mg2+-dependent ATPase which is distinct from the mitochondrial Mg2+-ATPase and at pH optimum 5.5 Km for ATP 1.7 mM Vmax 0.42 mumol hydrolyzed/mg/min. At least three protein components crude (Mr = 210,000, 160,000 115,000) are labeled with [gamma"32P]ATP 5.5. These phosphoproteins form rapidly in presence Mg2+, turn over bound phosphate when unlabeled added, dephosphorylate after incubation hydroxylamine. Vanadate, an inhibitor activity, blocks phosphorylation 210,000- 115,000-dalton proteins. 7.0, only 160,000-dalton proteins phosphorylated. While these phosphorylated intermediates have not been unambiguously identified as Mg2+-ATPase, finding such association that activity implies this enzyme differs mechanism proton pump it similar to metal ion pumps ((Na+-K+)-ATPase Ca2+-ATPase) mammalian membrane.