Calcium homeostasis in yeast cells exposed to high concentrations of calcium Roles of vacuolar H+‐ATPase and cellular ATP

FEBS Letters

Eilam, Y.¹  Halachmi, D.¹ 

[1] Department of Bacteriology, Hebrew University Hadassah Medical School, Jerusalem 91010, Israel

关键词: Saccharomyces cerevisiae;    Cytosolic calcium;    [Ca2+]i homeostasis;    ATP: Vacuolar H+-ATPase;   

DOI  :  10.1016/0014-5793(93)81739-M

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Cytosolic Ca²⁺ concentrations ([Ca²⁺]_i) were determined in haploid and diploid cells of Saccharomyces cerevisiae, loaded with indo-1 and exposed to media containing a range of Ca²⁺ concentrations. [Ca²⁺]_i homeostasis was maintained at the 100–150 nM level in cells which were pre-incubated with glucose and exposed to O.1 μM–1O mM Ca²⁺ in the medium. Slightly higher levels of [Ca²⁺]_i were determined in cells exposed to 50 mM Ca²⁺. Pre-incubation with metabolic inhibitors instead of glucose caused a reduction in cellular ATP levels and an impaired [Ca²⁺]_i homeostasis; [Ca²⁺]_i reached 800 nM in cells exposed to 10 mM CaCl₂. Cells of the Δvma4 mutant strain, with no functional vacuolar H¹-ATPase, had elevated levels of [Ca²⁺]_i, reaching 1.8 μM when pre-incubated with glucose and exposed to 10 mM CaCl₂. Higher levels of [Ca²⁺]_i were measured in the mutant cells which were pre-incubated with metabolic inhibitors. This result indicates the central role of the vacuoles in maintaining [Ca²⁺]_i-homeostasis and suggests the presence of an additional non-vacuolar ATP-requiring mechanism which contributes to keeping [Ca²⁺]_i at low levels.

【 授权许可】

Unknown