TMEM66SARAF is a protein that in humans is encoded by the SARAF gene, formerly known as TMEM66.FunctionSARAF is a negative regulator of the [Calcium release activated channel|store-operated calcium in biology|calcium channel] into cells. SARAF is an endoplasmic reticulum membrane resident protein that associates with STIM1, to facilitate the inactivation of SOCE. SARAF plays a key role in shaping cytoplasmic calcium signals and determining the content of the major intracellular Ca2+ stores in the cell. By doing so it is likely to be important in protecting cells from calcium overfilling.