contains four putative transmembrane segments. SCID patients are homozygous for a single missense mutation in ORAI1, and expression of wild-type ORAI1 in SCID T cells restores store-operated Ca2+ influx and the CRAC current (ICRAC). SOCE Store operated calcium entry (SOCE) is used to regulate basal calcium, refill intracellular Ca2+ stores, and execute a wide range of specialized activities. STIM and Orai are the essential components enabling the reconstitution of Ca2+ release-activated Ca2+ (CRAC) channels that mediate SOCE. Palty et al. (2012) reported the molecular identification of SARAF as a negative regulator of SOCE. It is an endoplasmic reticulum membrane resident protein that associates with STIM to facilitate slow Ca2+-dependent inactivation of SOCE. SARAF plays a key role in shaping cytosolic Ca2+ signals and determining the content of the major intracellular Ca2+ stores, a role that is likely to be important in protecting cells from Ca2+overfilling. See also Cation diffusion facilitator ORAI1 ORAI2 STIM1 STIM2 TRPC1 Transporter Classification Database References Protein families Integral membrane proteins Ion channels