ATP-driven Ca2+/H+ antiport in acid vesicles from Dictyostelium

  1. E K Rooney and
  2. J D Gross
  1. Department of Biochemistry, University of Oxford, United Kingdom.

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.

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  1. PNAS September 1, 1992 vol. 89 no. 17 8025-8029
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