Swiss-Prot Acc.Q13586.Plays a role in mediating store-operated Ca2+ entry (SOCE), a Ca2+ influx following depletion of intracellular Ca2+ stores (PubMed:15866891, PubMed:16005298, PubMed:16208375, PubMed:16537481, PubMed:16733527, PubMed:16766533, PubMed:16807233, PubMed:18854159, PubMed:19249086, PubMed:22464749, PubMed:24069340, PubMed:24351972, PubMed:24591628, PubMed:26322679, PubMed:25326555, PubMed:28219928). Acts as Ca2+ sensor in the endoplasmic reticulum via its EF-hand domain. Upon Ca2+ depletion, translocates from the endoplasmic reticulum to the plasma membrane where it activates the Ca2+ release-activated Ca2+ (CRAC) channel subunit ORAI1 (PubMed:16208375, PubMed:16537481). Involved in enamel formation (PubMed:24621671). Activated following interaction with STIMATE, leading to promote STIM1 conformational switch (PubMed:26322679).