Calcium release-activated calcium channel Orai1–STIM1 complex (Orai1–STIM1 CRAC channel complex)

The Calcium release-activated calcium channel Orai1–STIM1 complex is a macromolecular protein complex essential for store-operated calcium entry (SOCE) in non-excitable cells[1][2][6]. The complex forms at endoplasmic reticulum (ER)–plasma membrane (PM) junctions, where STIM1 (stromal interaction molecule 1), a calcium sensor in the ER, detects depletion of ER calcium stores and migrates to these junctions to directly bind and gate the Orai1 channel in the PM[2][3]. Activation of Orai1 by STIM1 leads to highly specific calcium influx, which is essential for activating downstream signaling, particularly in the immune system—such as T cell activation and gene transcription[1][2][3][6]. Genetic mutations in either Orai1 or STIM1 can abolish CRAC channel function, leading to severe immunodeficiency[6]; hyperactivation or dysregulation is implicated in autoimmunity and cancer. While targeted therapies directly against this channel complex are investigational, it remains a validated and promising drug target for autoimmune diseases, allergy, and some cancers due to its central role in calcium-dependent signaling pathways[1][6].

Other names

CRAC channel complexOrai1–STIM1 channel complexStore-operated calcium entry complexOrai1/STIM1 store-operated calcium channel

Blockade of channel-mediated calcium influx (for investigational drugs); Modulation of calcium-dependent signaling pathways