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J Biol Chem. 2000 Dec 8;275(49):38245-53.

Cytosolic Ca2+ homeostasis is a constitutive function of the V-ATPase in Saccharomyces cerevisiae.

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1
Department of Biochemistry and Molecular Biology, State University of New York, Upstate Medical University, Syracuse, New York 13210, USA.

Abstract

The vacuole is the major site of intracellular Ca(2+) storage in yeast and functions to maintain cytosolic Ca(2+) levels within a narrow physiological range via a Ca(2+) pump (Pmc1p) and a H(+)/Ca(2+) antiporter (Vcx1p) driven by the vacuolar H(+)-ATPase (V-ATPase). We examined the function of the V-ATPase in cytosolic Ca(2+) homeostasis by comparing responses to a brief Ca(2+) challenge of a V-ATPase mutant (vma2Delta) and wild-type cells treated with the V-ATPase inhibitor concanamycin A. The kinetics of the Ca(2+) response were determined using transgenic aequorin as an in vivo cytosolic Ca(2+) reporter system. In wild-type cells, the V-ATPase-driven Vcx1p was chiefly responsible for restoring cytosolic Ca(2+) concentrations after a brief pulse. In cells lacking V-ATPase activity, brief exposure to elevated Ca(2+) compromised viability, even when there was little change in the final cytosolic Ca(2+) concentration. vma2Delta cells were more efficient at restoring cytosolic [Ca(2+)] after a pulse than concanamycin-treated wild-type cells, suggesting long term loss of V-ATPase triggers compensatory mechanisms. This compensation was dependent on calcineurin, and was mediated primarily by Pmc1p.

PMID:
10991947
DOI:
10.1074/jbc.M006650200
[Indexed for MEDLINE]
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