ORAI1

ORAI1

A gene on chromosome 12q24.31 that encodes a Ca2+ release-activated Ca2+ (CRAC) channel subunit, which mediates Ca2+ influx following depletion of intracellular Ca2+ stores and channel activation by the Ca2+ sensor, STIM1. CRAC channels are the main pathway for Ca2+ influx in T cells and promote an immune response to pathogens by activating the transcription factor NFAT.

Molecular pathology
Defects in ORAI1 cause immune dysfunction with T-cell inactivation due to calcium entry defect type 1.
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References in periodicals archive ?
Studying the calcium channels known as ORAI1, ORAI2 and ORAI3 and their regulators STIM1 and STIM2 helps us to define ways to modulate immune responses for therapeutic use."
have demonstrated that deletion of the [Ca.sup.2+] channel Orai1 in pancreatic acinar cells ([Orai1.sup.-/-] mice) induces several signs of gut inflammation and bacterial overgrowth, leading to bacterial translocation, systemic infection, and death [33].
Variations in ORAI1 gene associated with Kawasaki disease.
Chiu et al., "Involvement of STIM1 and Orai1 in EGF-mediated cell growth in retinal pigment epithelial cells," Journal of Biomedical Science, vol.
Recently, a likely sensor for the luminal calcium concentration in the endoplasmic reticulum has been identified [47-49], and a second protein, Orai1 or CRACM, was identified as a modulator of CRAC ([Ca.sup.2+] release-activated [Ca.sup.2+] channels) or possibly the CRAC itself [50, 51].
Import occurs at the level of (i) cell plasma membrane through the calcium release-activated [Ca.sup.2+] channel protein 1 (ORAI1), the store-operated calcium entry channels (SOCE), and specific receptor-operated channels (ROC) such as AMPA, NMDA, TRPC, and the voltage-dependent calcium channels (VDCC); (ii) endoplasmic reticulum (ER) through the sarco/endoplasmic reticulum calcium ATPase (SERCA); (iii) mitochondria intermembrane space through the voltage-dependent anion channel (VDAC); and (v) in the matrix by the mitochondrial uniporter (MCU), in synergy with the mitochondrial calcium uptake (MICU) system.
After transfer, membranes were immunoblotted with the following primary antibodies: PMCA1, PMCA 4, and PMCA total (Affinity Bioreagents, Rockford, IL), SERCA 2 (Thermo Scientific, Pierce antibodies, Rockford, IL, USA), NCX1 (Swant, Bellinzona, Switzerland), STIM1 (Cell Signaling, Beverly, USA), Orai1 (Proteintech, USA), and IP3R1 (Millipore, USA).
Hogan said that they are not sure why, but theorized that septins rearrange the cellular membrane's structure to "corral" the key proteins STIM and ORAI1, and maybe other factors needed for the calcium channel to operate.
Trebak, "Stim1 and orai1 mediate crac currents and store-operated calcium entry important for endothelial cell proliferation," Circulation Research, vol.
Consequently, a calcium entry channel molecule (Orai1) is activated by STIM1 and elicits store-operated calcium entry (SOCE).