Ca(2+) release-activated Ca(2+) (CRAC) channel subunit which mediates Ca(2+) influx following depletion of intracellular Ca(2+) stores and channel activation by the Ca(2+) sensor, STIM1. CRAC channels are the main pathway for Ca(2+) influx in T-cells and promote the immune response to pathogens by activating the transcription factor NFAT. Plays a prominent role in Ca(2+) influx at the basolateral membrane of mammary epithelial cells independently of the Ca(2+) content of endoplasmic reticulum or Golgi stores. May mediate transepithelial transport of large quantities of Ca(2+) for milk secretion. Oxidation at Cys-196 leads to inactivation of channel activity. Interacts with STIM1 and STIM2; this regulates channel activity (By similarity). Interacts with CALM; this may displace STIM1 and STIM2 and might thereby modulate channel activity (PubMed:23109337). Interacts with CRACR2A/EFCAB4B; the interaction is direct and takes place in absence of Ca(2+) (By similarity). Forms a complex with CRACR2A/EFCAB4B and STIM1 at low concentration of Ca(2+), the complex dissociates at elevated Ca(2+) concentrations (By similarity). Interacts with SLC35G1 (By similarity). Interacts with UBQLN1 (By similarity). Interacts with ADCY8; interaction is calcium store depletion independent; interaction occurs in membrane raft; interaction increases markedly after store depletion; positively regulates SOCE-induced adenylate cyclase activity; contributes to the targeting of ADCY8 to discrete regions of the plasma membrane that are shielded from other calcium events (By similarity). Interacts with EFHB; the interaction takes place upon Ca(2+)-store depletion (By similarity). Interacts (via N- and C-termini) with ATP2C2 (via N-terminus); this interaction regulates Ca(2+) influx at the plasma membrane. Colocalizes with STIM1 at the cell membrane. N-glycosylated. N-glycosylation inhibits channel activity. Ubiquitinated. Cys-196 is oxidated, leading to inactivation of channel activity. Belongs to the Orai family. According to a report, ORAI1 has been shown to colocalize with UBQLN1 in the autophagosome as a target for autophagic degradation; ORAI1 is however not an autophagosomal protein.