Calcium release–activated calcium channel protein 1 (ORAI1)

Calcium release–activated calcium channel protein 1 (ORAI1) is a highly selective calcium ion channel found in the plasma membrane of human cells. It is a critical component of store-operated calcium entry (SOCE), which replenishes intracellular calcium stores, particularly after their depletion from the endoplasmic reticulum. The functional channel is formed by six Orai subunits arranged in a hexameric structure around a central aqueous pore. Activation occurs when internal calcium stores are depleted, triggering clustering of STIM1, which then interacts directly with ORAI channels. ORAI channels regulate basal cytosolic Ca²⁺ levels, refill intracellular Ca²⁺ stores, and support diverse cellular activities. Mutations or dysfunctions in ORAI proteins can lead to severe immunodeficiency syndromes.

Other names

CRACM1Orai