Calcium release-activated calcium channel complex (CRAC channel)

The Calcium Release-Activated Calcium (CRAC) channel complex, composed of the ER-resident calcium sensor STIM1 and the plasma membrane pore-forming subunit Orai1, is the primary mediator of store-operated calcium entry (SOCE) (Prakriya & Lewis, 2015, Physiol Rev). When calcium levels within the endoplasmic reticulum (ER) drop, the N-terminal luminal EF-hand domain of STIM1 dissociates from calcium, triggering a conformational change that leads to STIM1 oligomerization and translocation to ER-plasma membrane junctions (Stathopulos et al., 2008, JBC). At these junctions, STIM1 physically interacts with and activates Orai1 channels, allowing a sustained influx of extracellular calcium into the cytoplasm. This signaling pathway is essential for maintaining intracellular calcium homeostasis and driving downstream processes such as the activation of the NFAT transcription factor, which is critical for T-cell function and the immune response (Feske et al., 2006, Nature). Dysregulation of the STIM-Orai pathway is implicated in various pathologies, including severe combined immunodeficiency, autoimmune disorders, and several types of cancer where it promotes cell migration and proliferation. Consequently, the CRAC channel has emerged as a significant therapeutic target, with several small-molecule inhibitors currently in clinical trials for conditions like acute pancreatitis and plaque psoriasis (CalciMedica, 2024; Rhizen Pharmaceuticals, 2023).

Other names

STIM-ORAI complexStore-operated calcium channelSOCE complexSOC channelSTIM1-Orai1 complex

Inhibition of Orai1-mediated calcium conductance or disruption of the STIM1-Orai1 interaction to prevent store-operated calcium entry (SOCE).