Calcium release-activated calcium channel protein 1 (Orai1)

Calcium release-activated calcium channel protein 1 (Orai1) is a plasma membrane calcium channel that serves as the pore-forming subunit of the store-operated calcium (SOC) or calcium release-activated calcium (CRAC) channels. It is activated when calcium stores in the endoplasmic reticulum (ER) are depleted, a process detected by the ER calcium sensor STIM1, which binds and activates Orai1, leading to the opening of the channel and influx of extracellular calcium into the cell. This mechanism is central to store-operated calcium entry (SOCE), a key pathway in the signal transduction of immune cells, especially T lymphocytes, where it regulates activation, gene expression, and proliferation. Mutations in Orai1 cause immunodeficiency syndromes, illustrating its critical role in human immunity. Orai1 can assemble as a hexamer and is distinguished from other ion channels by its unique sequence and structural features. Although there are currently no approved drugs directly targeting Orai1, it is a major focus for research into immunosuppressive therapies and treatments for inflammatory and autoimmune diseases. Safety concerns primarily relate to the risk of over-suppressing immune function if Orai1 is inhibited systemically.

Other names

ORAI1CRACM1IMD9ORAT1TAM2TMEM142AORAI calcium release-activated calcium modulator 1

Inhibition reduces store-operated calcium entry (SOCE), thereby modulating immune cell activation and proliferation. Some inhibitors block the channel pore directly, preventing Ca²⁺ influx. Targeting Orai1 can suppress T-cell responses and inflammatory signaling.