Mutants of Saccharomyces cerevisiae lacking activity of the Ca2+/calmodulin-dependent protein phosphatase calcineurin, show sensitivity to high concentrations of sodium that is partly reversed by the external supply of Ca2+. On long-time exposure to NaCl stress the mutants display an increased intracellular Na+/K+ ratio which is partially corrected by the addition of Ca2+, improving the sodium efflux of not only calcineurin-defective cells but also wild-type cells. We also demonstrate that the NaCl sensitivity of cmd mutants, expressing modified forms of calmodulin that do not bind Ca2+, is strongly reversed by the addition of Ca2+. This effect is highly dependent on calcineurin, since the NaCl tolerance of a cmd1-3 strain, carrying an additional mutation in calcineurin, is only slightly assisted by Ca2+. A striking characteristic of the loss of function of calcineurin is a several-fold increased content of intracellular Ca2+, localized mainly in subcellular compartment(s). If the compartmentalized Ca2+ pool is brought back to normal levels by an additional inactivating mutation of the vacuolar Ca2+-transporting ATPase, such double mutants do not significantly improve their tolerance to NaCl.
|Evidence ID||Analyze ID||Interactor||Interactor Systematic Name||Interactor||Interactor Systematic Name||Type||Assay||Annotation||Action||Modification||Phenotype||Source||Reference||Note|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Gene Ontology Term||Gene Ontology Term ID||Qualifier||Aspect||Method||Evidence||Source||Assigned On||Annotation Extension||Reference|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Phenotype||Experiment Type||Experiment Type Category||Mutant Information||Strain Background||Chemical||Details||Reference|
|Evidence ID||Analyze ID||Regulator||Regulator Systematic Name||Target||Target Systematic Name||Experiment||Assay||Construct||Conditions||Strain Background||Reference|