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Title: Identification and partial purification of (Ca2+ or Mg2+)-ATPase in renal brush-border membranes. Author: Van Erum M, Lemmens R, Berden J, Teuchy H, Vanduffel L. Journal: Eur J Biochem; 1995 Jan 15; 227(1-2):150-60. PubMed ID: 7851380. Abstract: The protein responsible for the (Ca2+ or Mg2+)-ATPase activity in brush-border membranes from pig kidney tubular cells was characterized to distinguish this enzyme from the N-ethylmaleimide-sensitive Mg(2+)-ATPase, also present in renal brush borders. Both enzymes are clearly different in their pH optimum and their sensitivity to divalent cations, nucleoside 5'-triphosphates and inhibitors. Solubilization of the (Ca2+ or Mg2+)-ATPase from brush-border membrane vesicles was accomplished with Nonidet P-40 or dodecylmaltoside. However, simultaneous inactivation of the enzyme was inevitable. A tenfold enrichment of the ATPase activity was obtained by chromatofocusing of Nonidet-P-40-solubilized brush borders. A similar degree of purification was achieved by ion-exchange chromatography of dodecylmaltoside-solubilized preparations. From the SDS/polyacrylamide gels of partially purified (Ca2+ or Mg2+)-ATPase, a few protein bands could still be tentatively identified as responsible for the enzyme activity. Labeling of solubilized brush-border preparations with several radioactive ATP analogues also revealed that a protein band of molecular mass 90 kDa is the most probable candidate for the catalytic peptide of the (Ca2+ or Mg2+)-ATPase. Finally, immunoprecipitation as well as semi-dry blotting with antibodies generated against partially purified enzyme preparations, confirmed that a 90-kDa component is a reasonable candidate for the (Ca2+ or Mg2+)-ATPase in renal brush-border membranes.[Abstract] [Full Text] [Related] [New Search]