Plays a role in mediating store-operated Ca(2+) entry (SOCE), a Ca(2+) influx following depletion of intracellular Ca(2+) 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 Ca(2+) sensor in the endoplasmic reticulum via its EF-hand domain. Upon Ca(2+) depletion, translocates from the endoplasmic reticulum to the plasma membrane where it activates the Ca(2+) release-activated Ca(2+) (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).