SARAF is as family of eukaryotic proteins embedded in the ER. SARAF is SOCE-associated regulatory factor, where SOCE is store operated calcium entry. ie a mechanism governing calcium homoeostasis in the cell and the mitochondria. SOCE involves the enabling of Ca2+ release-activated Ca2+ (CRAC) channels. SARAF is a single pass ER membrane protein whose systolic-facing domain is responsible for activity and whose luminary-facing domain carries out a regulatory function in conjunction with another membrane protein STIM, an ER single pass membrane protein that detects changes in ER Ca2+ levels through its EF-hand, conserved Ca2+ binding domain. STIM is the major target for SARAF regulation, and thus SARAF negatively regulates the SOCE entry of calcium into cells protecting them from overfilling [1].

1: SARAF inactivates the store operated calcium entry machinery to prevent excess calcium refilling. Palty R, Raveh A, Kaminsky I, Meller R, Reuveny E; Cell. 2012;149:425-438. PMID:22464749