title: ATP-driven Ca2+/H+ antiport in acid vesicles from Dictyostelium.
abstract: Amoebae of the cellular slime mold Dictyostelium discoideum possess an extensive and dynamic endomembrane system that includes many types of acidic vacuoles. A light membrane fraction from Dictyostelium, rich in vacuolar-type H(+)-ATPase, has been described [Padh, H., Lavasa, M. & Steck, T.L. (1989) J. Cell Biol. 108, 865-874]. Here, we show that this "acidosomal" fraction also contains a high-affinity vanadate-sensitive Ca2+ uptake activity that is stimulated by the pH gradient formed by the H(+)-ATPase. We attribute this Ca2+ uptake to the presence of a H(+)-countertransporting Ca(2+)-ATPase, pumping Ca2+ into an acidic compartment.
authors.affiliation: Department of Biochemistry, University of Oxford, United Kingdom.
authors.forename: E K
authors.initials: EK
authors.lastname: Rooney
authors.forename: J D
authors.initials: JD
authors.lastname: Gross
mesh_terms: D000136:Acid-Base Equilibrium; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001693:Biological Transport, Active / Q000187:drug effects; D002118:Calcium / Q000378:metabolism; D000252:Calcium-Transporting ATPases / Q000378:metabolism*; D002451:Cell Compartmentation; D004023:Dictyostelium / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D018942:Macrolides; D014617:Vacuoles / Q000378:metabolism; D014638:Vanadates / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D018942:Macrolides; D014638:Vanadates; C040929:bafilomycin A1; D000252:Calcium-Transporting ATPases; D002118:Calcium