Orai1 (D90B10) Rabbit mAb #3280

Calcium is a key second messenger in many intracellular signaling pathways. Ca²⁺ signals control many cellular functions ranging from short term responses such as contraction and secretion to longer term regulation of cell growth and proliferation (1,2). Orai1 is the Ca²⁺ release-activated Ca²⁺ (CRAC) channel subunit which mediates Ca²⁺ influx following depletion of intracellular Ca²⁺ stores and channel activation by the Ca²⁺ sensor, STIM1 (3). The STIM1 and Orai1 are required for functional CRAC current and their co-expression leads to greatly amplified CRAC currents (4-7). There are three human homologues, Orai1, Orai2 and Orai3, which have been shown to be capable of forming store-operated channels (3, 5, 8). The Orai1, -2, and -3 channels are similarly inhibited by extracellular Ca²⁺, and Orai3 channels appeared to differ from Orai1 and -2 in being somewhat resistant to the process of Ca²⁺ depotentiation (9).