Regulates intracellular calcium levels and cell volume for survival in response to hypo-osmotic shock (PubMed:22910366). Involved in maintaining vacuole integrity and protecting the nuclear envelope upon hypo-osmotic shock (PubMed:25041276). Cortical endoplasmic reticulum. Up-regulated by both hyper- and hypo-osmotic shocks. EF-hand domain is involved in the detection of calcium concentration. Upon hypo-osmotic shock, cells display excessive increase in cell volume compared to wild-type and undergo cell death. Belongs to the MscS (TC 1.A.23) family.