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Arch Biochem Biophys. 2013 Sep 1;537(1):125-32. doi: 10.1016/j.abb.2013.07.005. Epub 2013 Jul 19.

Characterization of Ca(2+)/H(+) exchange in the plasma membrane of Saccharomyces cerevisiae.

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1
Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresources/College of Agriculture, Hainan University, Haikou, China.

Abstract

The characteristics of the Ca(2+)/H(+) exchange were directly investigated in functionally inverted (inside-out) plasma membrane vesicles isolated from yeast using an aqueous two-phase partitioning method. Results showed that following the generation of an inside-acid pH gradient (fluorescence quenching), addition of Ca(2+) caused movement of H(+) out of the vesicles (fluorescence recovery). The Ca(2+)/H(+) exchange displayed saturation kinetics with respect to extravesicular Ca(2+) and ATP concentrations in the plasma membrane, and showed specificity for Ca(2+). The protonophore FCCP (carbonyl cyanide p-(trifluoromethoxy) phenylhydrazone), abolished the fluorescence quenching and consequently inhibited Ca(2+)/H(+) exchange in plasma membrane vesicles. Vanadate, which is known to inhibit the plasma membrane H(+)-ATPase, significantly decreased the Ca(2+)-dependent transport of H(+) out of vesicles. When the electrical potential across the plasma membrane was dissipated with valinomycin and potassium, the rate of Ca(2+)/H(+) exchange increased compared to that of the control without valinomycin, indicating that the stoichiometric ratio for this exchange is greater than 2H(+):Ca(2+). These data suggest that Ca(2+) is transported out of yeast cells through a Ca(2+)/H(+) exchange system that is driven by the proton-motive force generated by the plasma membrane H(+)-ATPase.

KEYWORDS:

Ca(2+)/H(+) exchange; H(+)-ATPase; Plasma membrane; Saccharomyces cerevisiae

PMID:
23871844
DOI:
10.1016/j.abb.2013.07.005
[Indexed for MEDLINE]
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