Orai3 (ORAI calcium release-activated calcium modulator 3), also known as TMEM142C (transmembrane protein 142C), is a 295 amino acid multi-pass membrane protein that belongs to the Orai family of proteins. Localizing to the plasma membrane, Orai3 plays an important role in store-operated calcium (SOC) entry, a process involving Ca(2+) influx and replenishment of Ca(2+) stores formerly emptied through the action of inositol 1,4,5-trisphosphate production and other Ca(2+) mobilizing agents. CRAC channels are responsible for mediating calcium influx in T cells and play an important role in the immune response. Orai3, specifically, also acts as a regulator or component of the nuclear import of transcription factor NFAT.