{"gene":"ORAI2","run_date":"2026-06-10T05:19:53","timeline":{"discoveries":[{"year":2006,"finding":"Co-expression of ORAI2 with STIM1 in HEK293 cells produces large store-operated Ca2+-selective currents (CRAC currents), demonstrating that ORAI2 can function as a pore-forming subunit of store-operated Ca2+ channels together with STIM1; efficacy is in the order ORAI1 > ORAI2 > ORAI3.","method":"Co-transfection of HEK293 cells with STIM1 and ORAI2 followed by electrophysiological recording of Ca2+-selective store-operated currents and Ca2+ entry measurements","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — direct electrophysiological reconstitution replicated across multiple ORAI homologues with clear functional quantification; foundational study replicated by many subsequent labs","pmids":["16807233"],"is_preprint":false},{"year":2007,"finding":"Murine ORAI2 produces two splice variants (ORAI2L and ORAI2S) that both form functional CRAC channels when co-expressed with STIM1 in HEK293 cells, but not in RBL 2H3 cells, indicating cell-background dependence; ORAI2S shows strong Ca2+-dependent inactivation and exerts a dominant-negative effect on CRAC channel formation when co-expressed with STIM1 and ORAI1.","method":"Cloning of splice variants, Northern blot tissue expression, co-expression with STIM1 in HEK293 and RBL 2H3 cells, whole-cell patch-clamp electrophysiology","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — direct electrophysiological reconstitution with multiple variants in two cell lines; single lab but multiple orthogonal methods including cloning, immunodetection, and patch-clamp","pmids":["17463004"],"is_preprint":false},{"year":2015,"finding":"ORAI2 forms a hetero-oligomeric (likely hetero-tetramer) complex with ORAI1 in chondrocyte cells, as demonstrated by single-molecule TIRF imaging showing direct coupling; overexpression of ORAI2 decreases SOCE while knockdown increases SOCE, indicating ORAI2 reduces ORAI1 function within the heteromeric channel.","method":"siRNA knockdown and overexpression, fluorescence Ca2+ imaging, single-molecule total internal reflection fluorescence (TIRF) microscopy showing ORAI1-ORAI2 direct coupling","journal":"Cell calcium","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — single-molecule imaging with reciprocal gain/loss-of-function experiments supporting heteromeric channel model; multiple orthogonal methods in one study","pmids":["25769459"],"is_preprint":false},{"year":2017,"finding":"ORAI2 forms heteromeric CRAC channels with ORAI1 in mouse T cells and attenuates CRAC channel function; deletion of Orai2 increases SOCE, while deletion of Orai1 reduces SOCE; combined deletion of Orai1 and Orai2 abolishes SOCE and strongly impairs T cell function in vitro and in vivo, including antiviral responses and T cell-mediated autoimmunity.","method":"Genetic deletion (Orai1-/-, Orai2-/-, Orai1/Orai2 double-KO mice), Ca2+ imaging, electrophysiology (CRAC current), co-immunoprecipitation/FRET for heteromeric channel formation, in vivo mouse models of colitis and graft-versus-host disease","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple knockout models with reciprocal phenotypes, multiple orthogonal methods (electrophysiology, Ca2+ imaging, in vivo functional assays), independently reproduced concept","pmids":["28294127"],"is_preprint":false},{"year":2017,"finding":"Deletion of Orai2 in murine peritoneal mast cells augments endogenous CRAC currents, enhances Ca2+ rise triggered by IgE receptor or MAS-related GPCR stimulation, increases Ca2+-dependent degranulation, and intensifies mast cell-mediated anaphylaxis in vivo, demonstrating that Orai2 limits CRAC channel activity in mast cells.","method":"Orai2 gene knockout mouse, whole-cell patch-clamp (CRAC current density), Ca2+ imaging, degranulation assay, in vivo anaphylaxis model","journal":"Cell calcium","confidence":"High","confidence_rationale":"Tier 2 / Moderate — clean genetic KO with electrophysiology, Ca2+ imaging, and in vivo readouts; multiple orthogonal methods in one study","pmids":["29604961"],"is_preprint":false},{"year":2014,"finding":"ORAI2 is localized on secretory granules (not exclusively plasma membrane) in RBL-2H3 mast cells; knockdown of Orai2 attenuates antigen-stimulated Ca2+ release from Ca2+ stores and inhibits exocytotic release, but does not affect thapsigargin-induced Ca2+ release, suggesting a role in antigen-specific Ca2+ mobilization from granules.","method":"Subcellular fractionation and immunofluorescence localization, siRNA knockdown, Ca2+ imaging, exocytosis assay in RBL-2H3 cells","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 3 / Weak — single lab, localization by immunofluorescence and fractionation with functional follow-up; novel subcellular localization claim with limited mechanistic detail","pmids":["25044118"],"is_preprint":false},{"year":2015,"finding":"In proliferating (vs. contractile) pulmonary arterial smooth muscle cells, STIM2 and ORAI2 are upregulated and associated with increased store-operated Ca2+ entry (SOCE), whereas contractile-state cells show increased voltage-dependent Ca2+ entry; knockdown/functional data indicate STIM2 and Orai2 upregulation drives phenotypic transition to a proliferative state.","method":"Quantitative PCR, Western blot, Ca2+ imaging (SOCE assay), siRNA knockdown in PASMC phenotype switch model","journal":"American journal of physiology. Cell physiology","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — multiple methods (qPCR, Western, Ca2+ imaging) in a defined phenotypic model, but mechanistic pathway placement is correlative without rigorous epistasis","pmids":["25673771"],"is_preprint":false},{"year":2019,"finding":"ORAI2 is a central mediator of neuronal capacitative Ca2+ entry; Orai2-deficient neurons show significantly diminished Ca2+ signals induced by store depletion or oxygen/glucose deprivation, and Orai2-deficient mice are protected from ischemic neuronal death during acute stroke and ischemia/reperfusion.","method":"Genetic knockout mouse, Ca2+ imaging in primary neurons (store depletion and OGD), middle cerebral artery occlusion experimental stroke model","journal":"Stroke","confidence":"High","confidence_rationale":"Tier 2 / Moderate — clean genetic KO with direct Ca2+ imaging in neurons and in vivo stroke model; multiple functional readouts in one study","pmids":["31551038"],"is_preprint":false},{"year":2015,"finding":"ORAI2 expression is specifically upregulated at the G2/M phase of the cell cycle in brain capillary endothelial cells; at this phase, increased ORAI2 negatively modulates SOCE activity, and knockdown of ORAI2 at G2/M removes this SOCE decrease and partly attenuates cell proliferation.","method":"Cell synchronization by double thymidine blockage, qPCR and Western blot, siRNA knockdown, Ca2+ imaging (SOCE assay), cell proliferation assay","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — synchronized cell cycle with multiple methods; single lab but orthogonal approaches linking ORAI2 expression, SOCE, and proliferation","pmids":["25748572"],"is_preprint":false},{"year":2016,"finding":"ORAI2 contributes to SOCE in HL60 leukemia cells; Orai2 silencing significantly attenuates thapsigargin-induced SOCE, and combined silencing of Orai1 and Orai2 nearly abolishes SOCE; knockdown of Orai1 and Orai2 impairs HL60 cell migration in vitro, associated with impaired FAK tyrosine phosphorylation.","method":"siRNA knockdown, fluorescence Ca2+ imaging, transwell migration assay, Western blot for FAK phosphorylation","journal":"Biochimica et biophysica acta. Molecular cell research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — siRNA knockdown with Ca2+ imaging, migration assay, and FAK phosphorylation readout; single lab, multiple methods","pmids":["27865925"],"is_preprint":false},{"year":2020,"finding":"ORAI2 mediates store-operated Ca2+ entry and promotes gastric cancer cell proliferation, migration, tumor formation and metastasis; mechanistically, ORAI2-mediated SOC activity activates PI3K/Akt signaling and enhances FAK-mediated MAPK/ERK activation, promoting focal adhesion disassembly at the rear edge of migrating cells.","method":"Gain- and loss-of-function (overexpression and siRNA/shRNA knockdown) in gastric cancer cell lines and xenograft mouse models; Ca2+ imaging, Western blot for PI3K/Akt and FAK/MAPK/ERK, focal adhesion assays","journal":"Cancer research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal gain/loss-of-function with in vivo xenograft and multiple signaling pathway readouts; single lab","pmids":["33310726"],"is_preprint":false},{"year":2020,"finding":"ORAI2 is the primary pore subunit mediating capacitative Ca2+ entry in murine neutrophils; ORAI2-deficient neutrophils show decreased (not increased) Ca2+ influx, contrasting with enhanced SOCE seen in other immune cell types lacking ORAI2; this decreased SOCE in ORAI2-deficient neutrophils is correlated with altered KCa3.1-mediated membrane potential regulation.","method":"Genetic KO mouse (Orai1-/-, Orai2-/-, double KO), Ca2+ imaging, patch-clamp, membrane potential measurements, neutrophil functional assays (phagocytosis, degranulation, ROS, leukotriene), in vivo staphylococcal infection model","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 / Moderate — clean genetic KO with multiple orthogonal methods and mechanistic link to KCa3.1 membrane potential; single lab but rigorous","pmids":["32929002"],"is_preprint":false},{"year":2019,"finding":"LRRK2 kinase activity negatively regulates ORAI2 expression in dendritic cells; LRRK2 deficiency increases ORAI2 expression (but not ORAI1 or ORAI3) and enhances DC migration; silencing ORAI2 markedly decreases DC migration without affecting maturation markers, whereas ORAI1 silencing affects both migration and maturation markers.","method":"Genetic KO (LRRK2-/- mice), pharmacological LRRK2 kinase inhibition, siRNA knockdown of ORAI1/2/3, Ca2+ imaging, transwell migration assay, flow cytometry for maturation markers","journal":"FASEB journal","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic and pharmacological tools with specific isoform knockdown revealing selective ORAI2 regulation by LRRK2; single lab","pmids":["31166814"],"is_preprint":false},{"year":2021,"finding":"ORAI2 amplitude of CRAC current (ICRAC) is sensitive to changes in intracellular pH similarly to ORAI1, but unlike ORAI1, fast Ca2+-dependent inactivation kinetics of ORAI2 are unaffected by acidic intracellular pH; ORAI3-mediated ICRAC shows no pH dependence.","method":"Whole-cell patch-clamp of HEK293T cells heterologously expressing ORAI isoforms with STIM1, intracellular pH manipulation, Orai1-Orai3 chimera domain-swap analysis","journal":"The Journal of physiology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — direct electrophysiological characterization with chimeric constructs and pH clamping; rigorous biophysical dissection in a single study","pmids":["34877682"],"is_preprint":false},{"year":2022,"finding":"ORAI2 negatively modulates SOCE in astrocytes; Orai2 knockdown or knockout increases SOCE and Orai1 expression, and augments production of prostaglandin E2 (via upregulated Ptges and Ptgs2) in TNFα/IL1α-stimulated astrocytes, demonstrating that ORAI2 restrains inflammatory PGE2 production in the CNS.","method":"siRNA knockdown and genetic KO (Orai2-KO) in primary astrocytes, Ca2+ imaging, qPCR and Western blot for Ptges/Ptgs2/Orai1, PGE2 ELISA","journal":"Glia","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic KO confirmed with siRNA knockdown, multiple readouts linking ORAI2 to SOCE and PGE2 pathway; single lab","pmids":["35506586"],"is_preprint":false},{"year":2023,"finding":"NSUN2-mediated m5C modification of ORAI2 mRNA increases its stability and expression; YBX1 acts as the 'reader' of this m5C modification site; upstream, fatty acids from omental adipocytes activate the AMPK pathway to upregulate E2F1, which promotes NSUN2 transcription, thereby driving ORAI2 expression and gastric cancer peritoneal metastasis.","method":"RNA bisulfite sequencing (m5C mapping), RIP (RNA immunoprecipitation) for NSUN2 and YBX1, mRNA stability assay, ChIP for E2F1 on NSUN2 promoter, functional colonization/metastasis assays","journal":"Oncogene","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple biochemical methods (m5C mapping, RIP, ChIP) establishing post-transcriptional regulation; single lab","pmids":["37130916"],"is_preprint":false},{"year":2024,"finding":"ORAI2 mediates a SOCE-dependent signaling axis (ORAI2/JNK/NFAT1) that drives TGF-β1-mediated fibrogenesis in irradiated salivary glands; inhibition of SOCE reduces fibrosis in an ORAI2-dependent manner, and pharmacological inhibition of NFAT1 restores saliva flow to ~85% of normal in irradiated mice.","method":"RNA sequencing of irradiated mouse salivary glands, SOCE inhibition (SKF96365, YM58483), siRNA/KO of ORAI2, Western blot for JNK/NFAT1/TGF-β1, in vivo irradiation model with pharmacological NFAT1 inhibition","journal":"International journal of radiation oncology, biology, physics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic and pharmacological tools with in vivo validation; ORAI2/JNK/NFAT1/TGF-β1 pathway placed by multiple orthogonal methods in single lab","pmids":["39384103"],"is_preprint":false},{"year":2021,"finding":"ORAI2 downregulation in human neuroglioma H4 cells significantly increases SOCE amplitude; in Aβ-secreting H4-APPswe cells, ORAI2 downregulation (increased SOCE) decreases Aβ42 accumulation, whereas SOCE inhibition increases Aβ42 accumulation, establishing that ORAI2 negatively regulates SOCE and thereby modulates amyloid-beta production.","method":"siRNA knockdown and overexpression, Ca2+ imaging (SOCE measurement), SOCE inhibitor (BTP2), Aβ42 ELISA in H4-APPswe cells","journal":"International journal of molecular sciences","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — reciprocal gain/loss-of-function with functional Ca2+ and Aβ42 readouts, but single lab and single cell line model","pmids":["32722509"],"is_preprint":false}],"current_model":"ORAI2 is a pore-forming subunit of Ca2+ release-activated Ca2+ (CRAC) channels that requires STIM1 for activation; it preferentially forms heteromeric channels with ORAI1 to attenuate the magnitude of store-operated Ca2+ entry (SOCE) in most cell types (T cells, mast cells, astrocytes, chondrocytes), though in neutrophils it contributes positively to SOCE via a KCa3.1-dependent membrane potential mechanism; ORAI2-mediated SOCE regulates diverse downstream processes including NFAT activation, PI3K/Akt and FAK/MAPK/ERK signaling, PGE2 production, neuronal Ca2+ overload during ischemia, and cell cycle progression, with its expression controlled post-transcriptionally by NSUN2-mediated m5C mRNA modification."},"narrative":{"mechanistic_narrative":"ORAI2 is a pore-forming subunit of store-operated Ca2+ release-activated Ca2+ (CRAC) channels that, together with STIM1, conducts Ca2+-selective currents upon store depletion, with intrinsic conductance efficacy ranking ORAI1 > ORAI2 > ORAI3 [PMID:16807233]. In most cell types ORAI2 assembles into hetero-oligomeric (likely hetero-tetrameric) channels with ORAI1, where it acts as a negative rheostat: overexpression lowers and loss-of-function raises store-operated Ca2+ entry (SOCE), as demonstrated by single-molecule coupling in chondrocytes and reciprocal knockout phenotypes in T cells [PMID:25769459, PMID:28294127]. This attenuating role is conserved across mast cells, astrocytes, and neuroglioma, where ORAI2 deletion or knockdown augments CRAC currents and amplifies downstream Ca2+-dependent outputs including mast cell degranulation and anaphylaxis, astrocytic PGE2 production, and amyloid-beta handling [PMID:29604961, PMID:35506586, PMID:32722509]. A second ORAI2 splice variant (ORAI2S) displays strong Ca2+-dependent inactivation and a dominant-negative effect on channel assembly, providing an additional layer of conductance tuning [PMID:17463004]. In specific cellular contexts ORAI2 instead serves as the primary positive driver of SOCE: it is the dominant pore subunit in neutrophils, where its loss decreases Ca2+ influx through a KCa3.1-dependent membrane-potential mechanism, and it sustains capacitative entry in neurons, where Orai2 deficiency protects against ischemic neuronal death [PMID:32929002, PMID:31551038]. ORAI2-mediated SOCE feeds defined signaling axes that govern proliferation, migration, and pathology — activating PI3K/Akt and FAK/MAPK/ERK to promote gastric cancer growth and metastasis, and an ORAI2/JNK/NFAT1 axis driving TGF-beta1-mediated salivary gland fibrosis [PMID:33310726, PMID:39384103]. ORAI2 expression is itself regulated post-transcriptionally by NSUN2-mediated m5C modification of its mRNA, read by YBX1 to enhance transcript stability [PMID:37130916], and is cell-cycle-dependent, peaking at G2/M to restrain SOCE [PMID:25748572].","teleology":[{"year":2006,"claim":"Established that ORAI2 is not merely an ORAI1 homolog but an autonomous pore-forming CRAC channel subunit, answering whether it could conduct store-operated Ca2+ current at all.","evidence":"Co-transfection of ORAI2 with STIM1 in HEK293 cells and electrophysiological recording of Ca2+-selective store-operated currents","pmids":["16807233"],"confidence":"High","gaps":["Did not address ORAI2 behavior in heteromeric channels with ORAI1","Quantitative efficacy ranking measured only in heterologous overexpression"]},{"year":2007,"claim":"Revealed splice-variant and cell-background control of ORAI2 channel function, showing ORAI2S can act dominant-negatively on CRAC assembly and adding a tuning mechanism beyond simple expression level.","evidence":"Cloning of murine ORAI2L/ORAI2S splice variants, expression with STIM1 in HEK293 and RBL 2H3 cells, whole-cell patch-clamp","pmids":["17463004"],"confidence":"High","gaps":["Functional difference between HEK293 and RBL 2H3 not mechanistically explained","Physiological relevance of ORAI2S dominant-negative effect in native cells not established"]},{"year":2014,"claim":"Proposed a non-canonical localization of ORAI2 on secretory granules and a role in antigen-specific Ca2+ mobilization, distinct from a purely plasma-membrane channel function.","evidence":"Subcellular fractionation, immunofluorescence, siRNA knockdown, Ca2+ imaging and exocytosis assay in RBL-2H3 mast cells","pmids":["25044118"],"confidence":"Medium","gaps":["Granular localization shown by fractionation/immunofluorescence only, no reconstitution of granule channel activity","Single cell line; not confirmed in primary mast cells"]},{"year":2015,"claim":"Defined ORAI2 as a negative modulator within ORAI1-ORAI2 heteromeric channels, answering how it shapes SOCE magnitude rather than simply adding conductance.","evidence":"Single-molecule TIRF imaging of ORAI1-ORAI2 coupling plus reciprocal knockdown/overexpression and Ca2+ imaging in chondrocytes","pmids":["25769459"],"confidence":"High","gaps":["Exact stoichiometry of the hetero-oligomer not resolved","Whether attenuation arises from altered gating or reduced ORAI1 incorporation not determined"]},{"year":2015,"claim":"Linked ORAI2 expression and SOCE to cell-state transitions and proliferation, beginning to connect channel function to physiological outcomes.","evidence":"qPCR, Western blot, Ca2+ imaging and siRNA knockdown in pulmonary arterial smooth muscle and brain capillary endothelial cell-cycle models","pmids":["25673771","25748572"],"confidence":"Medium","gaps":["Pathway placement largely correlative without epistasis","Cell-cycle-dependent upregulation mechanism at G2/M not defined"]},{"year":2017,"claim":"Provided definitive in vivo genetic proof that ORAI2 attenuates CRAC function in immune cells, with reciprocal SOCE phenotypes for Orai1 vs Orai2 deletion and physiological consequences for T cell and mast cell biology.","evidence":"Orai1, Orai2 single and double knockout mice with CRAC electrophysiology, Ca2+ imaging, Co-IP/FRET, and in vivo immune and anaphylaxis models","pmids":["28294127","29604961"],"confidence":"High","gaps":["Molecular basis of the attenuating effect within native heteromers not resolved","Tissue-specific expression ratios governing the degree of attenuation not quantified"]},{"year":2019,"claim":"Showed ORAI2 can be the dominant positive mediator of SOCE in specific lineages, overturning a uniform attenuator model; established neuronal and dendritic-cell roles and a regulatory link to LRRK2.","evidence":"Orai2 knockout neurons and mice with Ca2+ imaging and stroke models; LRRK2-KO/inhibitor with isoform-specific siRNA and migration assays","pmids":["31551038","31166814"],"confidence":"High","gaps":["Why ORAI2 is positive in neurons but attenuating elsewhere not mechanistically explained","Mechanism by which LRRK2 kinase activity selectively suppresses ORAI2 expression unknown"]},{"year":2020,"claim":"Resolved the context-dependence by identifying a KCa3.1-dependent membrane-potential mechanism that makes ORAI2 the primary positive SOCE driver in neutrophils, and connected ORAI2 SOCE to oncogenic PI3K/Akt and FAK/MAPK/ERK signaling in cancer.","evidence":"Neutrophil knockout mice with patch-clamp and membrane-potential measurements; gain/loss-of-function in gastric cancer lines and xenografts with signaling readouts","pmids":["32929002","33310726","27865925"],"confidence":"High","gaps":["How KCa3.1 coupling differs between neutrophils and attenuator cell types not defined","Direct biochemical link between ORAI2 channel activity and PI3K/FAK activation not established"]},{"year":2021,"claim":"Distinguished ORAI2 biophysically from its homologs and extended its negative-regulatory role to amyloid-beta production, refining isoform-specific channel properties.","evidence":"Whole-cell patch-clamp with pH manipulation and ORAI1-ORAI3 chimeras; siRNA/overexpression with Abeta42 ELISA in H4-APPswe cells","pmids":["34877682","32722509"],"confidence":"High","gaps":["Structural determinant of ORAI2 pH-insensitive inactivation not mapped to specific residues","Abeta findings limited to a single neuroglioma cell line"]},{"year":2022,"claim":"Demonstrated ORAI2 restrains inflammatory and fibrotic Ca2+-dependent programs, linking it to CNS PGE2 production and to a JNK/NFAT1/TGF-beta1 fibrogenic axis with therapeutic relevance.","evidence":"Astrocyte siRNA/KO with Ca2+ imaging, qPCR/Western and PGE2 ELISA; irradiated salivary gland model with SOCE/NFAT1 inhibition and ORAI2 KO","pmids":["35506586","39384103"],"confidence":"Medium","gaps":["Whether ORAI2-PGE2 and ORAI2-fibrosis effects are direct channel functions or secondary to ORAI1 upregulation not separated","NFAT1 activation mechanism downstream of ORAI2 in fibroblasts not detailed"]},{"year":2023,"claim":"Identified the upstream post-transcriptional control of ORAI2 abundance, explaining how its expression is tuned in disease via an NSUN2/m5C/YBX1 axis.","evidence":"RNA bisulfite sequencing, RIP for NSUN2/YBX1, mRNA stability assays, E2F1 ChIP and metastasis assays in gastric cancer","pmids":["37130916"],"confidence":"Medium","gaps":["Whether m5C regulation of ORAI2 operates outside gastric cancer not tested","Single lab; YBX1-dependent stabilization not reconstituted in vitro"]},{"year":null,"claim":"The molecular determinant that switches ORAI2 between attenuator (T cells, mast cells, astrocytes) and primary positive conductor (neutrophils, neurons) remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structural model of native ORAI1-ORAI2 heteromer stoichiometry across cell types","Relative ORAI1/ORAI2/STIM expression ratios that dictate sign of the effect not systematically mapped"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0005215","term_label":"transporter activity","supporting_discovery_ids":[0,1,3,11,13]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[0,2,3]},{"term_id":"GO:0031410","term_label":"cytoplasmic vesicle","supporting_discovery_ids":[5]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[3,10,16]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[3,4,11]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[7,10,16,17]}],"complexes":["ORAI1-ORAI2 heteromeric CRAC channel"],"partners":["ORAI1","STIM1","STIM2"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q96SN7","full_name":"Protein orai-2","aliases":["CAP-binding protein complex-interacting protein 2","Transmembrane protein 142B"],"length_aa":254,"mass_kda":28.6,"function":"Pore-forming subunit of inward rectifying Ca(2+) release-activated Ca(2+) (CRAC) channels. Assembles with ORAI1 and ORAI3 to form hexameric CRAC channels that mediate Ca(2+) influx upon depletion of endoplasmic reticulum Ca(2+) store and channel activation by Ca(2+) sensor STIM1, a process known as store-operated Ca(2+) entry (SOCE). Various pore subunit combinations may account for distinct CRAC channel spatiotemporal and cell-type specific dynamics. ORAI1 mainly contributes to the generation of Ca(2+) plateaus involved in sustained Ca(2+) entry and is dispensable for cytosolic Ca(2+) oscillations, whereas ORAI2 and ORAI3 generate oscillatory patterns. CRAC channels assemble in Ca(2+) signaling microdomains where Ca(2+) influx is coupled to calmodulin and calcineurin signaling and activation of NFAT transcription factors recruited to ORAI1 via AKAP5. CRAC channels are the main pathway for Ca(2+) influx in T cells and promote the immune response to pathogens by activating NFAT-dependent cytokine and chemokine transcription","subcellular_location":"Cell membrane","url":"https://www.uniprot.org/uniprotkb/Q96SN7/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/ORAI2","classification":"Not Classified","n_dependent_lines":8,"n_total_lines":1208,"dependency_fraction":0.006622516556291391},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/ORAI2","total_profiled":1310},"omim":[{"mim_id":"614178","title":"CALCIUM RELEASE-ACTIVATED CALCIUM CHANNEL REGULATOR 2A; CRACR2A","url":"https://www.omim.org/entry/614178"},{"mim_id":"610930","title":"ORAI CALCIUM RELEASE-ACTIVATED CALCIUM MODULATOR 3; ORAI3","url":"https://www.omim.org/entry/610930"},{"mim_id":"610929","title":"ORAI CALCIUM RELEASE-ACTIVATED CALCIUM MODULATOR 2; ORAI2","url":"https://www.omim.org/entry/610929"},{"mim_id":"610277","title":"ORAI CALCIUM RELEASE-ACTIVATED CALCIUM MODULATOR 1; ORAI1","url":"https://www.omim.org/entry/610277"},{"mim_id":"605921","title":"STROMAL INTERACTION MOLECULE 1; STIM1","url":"https://www.omim.org/entry/605921"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Nucleoplasm","reliability":"Supported"},{"location":"Mitochondria","reliability":"Supported"},{"location":"Cytosol","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in many","driving_tissues":[],"url":"https://www.proteinatlas.org/search/ORAI2"},"hgnc":{"alias_symbol":["CBCIP2","FLJ12474","FLJ14733","H_NH0514P08.8"],"prev_symbol":["C7orf19","TMEM142B"]},"alphafold":{"accession":"Q96SN7","domains":[{"cath_id":"1.20.140.140","chopping":"51-178_191-243","consensus_level":"medium","plddt":86.1126,"start":51,"end":243}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q96SN7","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q96SN7-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q96SN7-F1-predicted_aligned_error_v6.png","plddt_mean":80.12},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=ORAI2","jax_strain_url":"https://www.jax.org/strain/search?query=ORAI2"},"sequence":{"accession":"Q96SN7","fasta_url":"https://rest.uniprot.org/uniprotkb/Q96SN7.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q96SN7/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q96SN7"}},"corpus_meta":[{"pmid":"16807233","id":"PMC_16807233","title":"Large store-operated calcium selective currents due to co-expression of Orai1 or Orai2 with the intracellular calcium sensor, Stim1.","date":"2006","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/16807233","citation_count":462,"is_preprint":false},{"pmid":"28294127","id":"PMC_28294127","title":"ORAI2 modulates store-operated calcium entry and T cell-mediated immunity.","date":"2017","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/28294127","citation_count":178,"is_preprint":false},{"pmid":"25673771","id":"PMC_25673771","title":"Upregulated expression of STIM2, TRPC6, and Orai2 contributes to the transition of pulmonary arterial smooth muscle cells from a contractile to proliferative phenotype.","date":"2015","source":"American journal of physiology. Cell physiology","url":"https://pubmed.ncbi.nlm.nih.gov/25673771","citation_count":104,"is_preprint":false},{"pmid":"33310726","id":"PMC_33310726","title":"ORAI2 Promotes Gastric Cancer Tumorigenicity and Metastasis through PI3K/Akt Signaling and MAPK-Dependent Focal Adhesion Disassembly.","date":"2020","source":"Cancer research","url":"https://pubmed.ncbi.nlm.nih.gov/33310726","citation_count":95,"is_preprint":false},{"pmid":"17463004","id":"PMC_17463004","title":"Murine ORAI2 splice variants form functional Ca2+ release-activated Ca2+ (CRAC) channels.","date":"2007","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/17463004","citation_count":92,"is_preprint":false},{"pmid":"37130916","id":"PMC_37130916","title":"Peritoneal high-fat environment promotes peritoneal metastasis of gastric cancer cells through activation of NSUN2-mediated ORAI2 m5C modification.","date":"2023","source":"Oncogene","url":"https://pubmed.ncbi.nlm.nih.gov/37130916","citation_count":61,"is_preprint":false},{"pmid":"27865925","id":"PMC_27865925","title":"Orai1 and Orai2 mediate store-operated calcium entry that regulates HL60 cell migration and FAK phosphorylation.","date":"2016","source":"Biochimica et biophysica acta. Molecular cell research","url":"https://pubmed.ncbi.nlm.nih.gov/27865925","citation_count":47,"is_preprint":false},{"pmid":"29604961","id":"PMC_29604961","title":"Deletion of Orai2 augments endogenous CRAC currents and degranulation in mast cells leading to enhanced anaphylaxis.","date":"2017","source":"Cell calcium","url":"https://pubmed.ncbi.nlm.nih.gov/29604961","citation_count":45,"is_preprint":false},{"pmid":"32929002","id":"PMC_32929002","title":"ORAI1 and ORAI2 modulate murine neutrophil calcium signaling, cellular activation, and host defense.","date":"2020","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/32929002","citation_count":41,"is_preprint":false},{"pmid":"25769459","id":"PMC_25769459","title":"Orai1-Orai2 complex is involved in store-operated calcium entry in chondrocyte cell lines.","date":"2015","source":"Cell calcium","url":"https://pubmed.ncbi.nlm.nih.gov/25769459","citation_count":40,"is_preprint":false},{"pmid":"31551038","id":"PMC_31551038","title":"Loss of Orai2-Mediated Capacitative Ca2+ Entry Is Neuroprotective in Acute Ischemic Stroke.","date":"2019","source":"Stroke","url":"https://pubmed.ncbi.nlm.nih.gov/31551038","citation_count":38,"is_preprint":false},{"pmid":"32882268","id":"PMC_32882268","title":"Orai-1 and Orai-2 regulate oral cancer cell migration and colonisation by suppressing Akt/mTOR/NF-κB signalling.","date":"2020","source":"Life sciences","url":"https://pubmed.ncbi.nlm.nih.gov/32882268","citation_count":37,"is_preprint":false},{"pmid":"35008277","id":"PMC_35008277","title":"Orai2 Modulates Store-Operated Ca2+ Entry and Cell Cycle Progression in Breast Cancer Cells.","date":"2021","source":"Cancers","url":"https://pubmed.ncbi.nlm.nih.gov/35008277","citation_count":25,"is_preprint":false},{"pmid":"25748572","id":"PMC_25748572","title":"Regulation of store-operated Ca2+ entry activity by cell cycle dependent up-regulation of Orai2 in brain capillary endothelial cells.","date":"2015","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/25748572","citation_count":25,"is_preprint":false},{"pmid":"32722509","id":"PMC_32722509","title":"ORAI2 Down-Regulation Potentiates SOCE and Decreases Aβ42 Accumulation in Human Neuroglioma Cells.","date":"2020","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/32722509","citation_count":19,"is_preprint":false},{"pmid":"25044118","id":"PMC_25044118","title":"Orai-2 is localized on secretory granules and regulates antigen-evoked Ca²⁺ mobilization and exocytosis in mast cells.","date":"2014","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/25044118","citation_count":15,"is_preprint":false},{"pmid":"31772693","id":"PMC_31772693","title":"Identification of Key Pathways and Genes in the Orai2 Mediated Classical and Mesenchymal Subtype of Glioblastoma by Bioinformatic Analyses.","date":"2019","source":"Disease markers","url":"https://pubmed.ncbi.nlm.nih.gov/31772693","citation_count":13,"is_preprint":false},{"pmid":"34877682","id":"PMC_34877682","title":"Orai1- and Orai2-, but not Orai3-mediated ICRAC is regulated by intracellular pH.","date":"2021","source":"The Journal of physiology","url":"https://pubmed.ncbi.nlm.nih.gov/34877682","citation_count":10,"is_preprint":false},{"pmid":"31166814","id":"PMC_31166814","title":"Leucine-rich repeat kinase 2 regulates mouse dendritic cell migration by ORAI2.","date":"2019","source":"FASEB journal : official publication of the Federation of American Societies for Experimental Biology","url":"https://pubmed.ncbi.nlm.nih.gov/31166814","citation_count":9,"is_preprint":false},{"pmid":"38709251","id":"PMC_38709251","title":"Sodium Houttuyfonate Alleviates Monocrotaline-induced Pulmonary Hypertension by Regulating Orai1 and Orai2.","date":"2024","source":"American journal of respiratory cell and molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/38709251","citation_count":9,"is_preprint":false},{"pmid":"35506586","id":"PMC_35506586","title":"Orai2 channel regulates prostaglandin E2 production in TNFα/IL1α-stimulated astrocytes.","date":"2022","source":"Glia","url":"https://pubmed.ncbi.nlm.nih.gov/35506586","citation_count":8,"is_preprint":false},{"pmid":"39384103","id":"PMC_39384103","title":"ORAI2 is Important for the Development of Early-Stage Postirradiation Fibrosis in Salivary Glands.","date":"2024","source":"International journal of radiation oncology, biology, physics","url":"https://pubmed.ncbi.nlm.nih.gov/39384103","citation_count":6,"is_preprint":false},{"pmid":"34595206","id":"PMC_34595206","title":"X-Ray Causes mRNA Transcripts Change to Enhance Orai2-Mediated Ca2+ Influx in Rat Brain Microvascular Endothelial Cells.","date":"2021","source":"Frontiers in molecular biosciences","url":"https://pubmed.ncbi.nlm.nih.gov/34595206","citation_count":5,"is_preprint":false},{"pmid":"37119920","id":"PMC_37119920","title":"Bisbenzylisoquinoline alkaloids from Plumula Nelumbinis inhibit vascular smooth muscle cells migration and proliferation by regulating the ORAI2/Akt pathway.","date":"2023","source":"Phytochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/37119920","citation_count":4,"is_preprint":false},{"pmid":"36012752","id":"PMC_36012752","title":"Blockade of Platelet Glycoprotein Ibα Augments Neuroprotection in Orai2-Deficient Mice during Middle Cerebral Artery Occlusion.","date":"2022","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/36012752","citation_count":1,"is_preprint":false},{"pmid":"36831699","id":"PMC_36831699","title":"Correction: Sanchez-Collado et al. Orai2 Modulates Store-Operated Ca2+ Entry and Cell Cycle Progression in Breast Cancer Cells. Cancers 2021, 14, 114.","date":"2023","source":"Cancers","url":"https://pubmed.ncbi.nlm.nih.gov/36831699","citation_count":1,"is_preprint":false},{"pmid":"42065066","id":"PMC_42065066","title":"Circ72688 Drives Breast Cancer Invasion and Metastasis via the miR-654-5p/ORAI2 Axis.","date":"2026","source":"Oncology research","url":"https://pubmed.ncbi.nlm.nih.gov/42065066","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2025.10.08.681053","title":"Endothelial CYB5R3 couples store-operated calcium entry to TRPV2 activation and vascular fitness","date":"2025-10-08","source":"bioRxiv","url":"https://doi.org/10.1101/2025.10.08.681053","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":17350,"output_tokens":5108,"usd":0.064335,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":13389,"output_tokens":4345,"usd":0.087785,"stage2_stop_reason":"end_turn"},"total_usd":0.15212,"stage1_batch_id":"msgbatch_013a8chtv3AWyTqv4z4sEF4C","stage2_batch_id":"msgbatch_01AHsuW63vinsvuTgzmQ3n62","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2006,\n      \"finding\": \"Co-expression of ORAI2 with STIM1 in HEK293 cells produces large store-operated Ca2+-selective currents (CRAC currents), demonstrating that ORAI2 can function as a pore-forming subunit of store-operated Ca2+ channels together with STIM1; efficacy is in the order ORAI1 > ORAI2 > ORAI3.\",\n      \"method\": \"Co-transfection of HEK293 cells with STIM1 and ORAI2 followed by electrophysiological recording of Ca2+-selective store-operated currents and Ca2+ entry measurements\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — direct electrophysiological reconstitution replicated across multiple ORAI homologues with clear functional quantification; foundational study replicated by many subsequent labs\",\n      \"pmids\": [\"16807233\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Murine ORAI2 produces two splice variants (ORAI2L and ORAI2S) that both form functional CRAC channels when co-expressed with STIM1 in HEK293 cells, but not in RBL 2H3 cells, indicating cell-background dependence; ORAI2S shows strong Ca2+-dependent inactivation and exerts a dominant-negative effect on CRAC channel formation when co-expressed with STIM1 and ORAI1.\",\n      \"method\": \"Cloning of splice variants, Northern blot tissue expression, co-expression with STIM1 in HEK293 and RBL 2H3 cells, whole-cell patch-clamp electrophysiology\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — direct electrophysiological reconstitution with multiple variants in two cell lines; single lab but multiple orthogonal methods including cloning, immunodetection, and patch-clamp\",\n      \"pmids\": [\"17463004\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"ORAI2 forms a hetero-oligomeric (likely hetero-tetramer) complex with ORAI1 in chondrocyte cells, as demonstrated by single-molecule TIRF imaging showing direct coupling; overexpression of ORAI2 decreases SOCE while knockdown increases SOCE, indicating ORAI2 reduces ORAI1 function within the heteromeric channel.\",\n      \"method\": \"siRNA knockdown and overexpression, fluorescence Ca2+ imaging, single-molecule total internal reflection fluorescence (TIRF) microscopy showing ORAI1-ORAI2 direct coupling\",\n      \"journal\": \"Cell calcium\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — single-molecule imaging with reciprocal gain/loss-of-function experiments supporting heteromeric channel model; multiple orthogonal methods in one study\",\n      \"pmids\": [\"25769459\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"ORAI2 forms heteromeric CRAC channels with ORAI1 in mouse T cells and attenuates CRAC channel function; deletion of Orai2 increases SOCE, while deletion of Orai1 reduces SOCE; combined deletion of Orai1 and Orai2 abolishes SOCE and strongly impairs T cell function in vitro and in vivo, including antiviral responses and T cell-mediated autoimmunity.\",\n      \"method\": \"Genetic deletion (Orai1-/-, Orai2-/-, Orai1/Orai2 double-KO mice), Ca2+ imaging, electrophysiology (CRAC current), co-immunoprecipitation/FRET for heteromeric channel formation, in vivo mouse models of colitis and graft-versus-host disease\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple knockout models with reciprocal phenotypes, multiple orthogonal methods (electrophysiology, Ca2+ imaging, in vivo functional assays), independently reproduced concept\",\n      \"pmids\": [\"28294127\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Deletion of Orai2 in murine peritoneal mast cells augments endogenous CRAC currents, enhances Ca2+ rise triggered by IgE receptor or MAS-related GPCR stimulation, increases Ca2+-dependent degranulation, and intensifies mast cell-mediated anaphylaxis in vivo, demonstrating that Orai2 limits CRAC channel activity in mast cells.\",\n      \"method\": \"Orai2 gene knockout mouse, whole-cell patch-clamp (CRAC current density), Ca2+ imaging, degranulation assay, in vivo anaphylaxis model\",\n      \"journal\": \"Cell calcium\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean genetic KO with electrophysiology, Ca2+ imaging, and in vivo readouts; multiple orthogonal methods in one study\",\n      \"pmids\": [\"29604961\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"ORAI2 is localized on secretory granules (not exclusively plasma membrane) in RBL-2H3 mast cells; knockdown of Orai2 attenuates antigen-stimulated Ca2+ release from Ca2+ stores and inhibits exocytotic release, but does not affect thapsigargin-induced Ca2+ release, suggesting a role in antigen-specific Ca2+ mobilization from granules.\",\n      \"method\": \"Subcellular fractionation and immunofluorescence localization, siRNA knockdown, Ca2+ imaging, exocytosis assay in RBL-2H3 cells\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, localization by immunofluorescence and fractionation with functional follow-up; novel subcellular localization claim with limited mechanistic detail\",\n      \"pmids\": [\"25044118\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"In proliferating (vs. contractile) pulmonary arterial smooth muscle cells, STIM2 and ORAI2 are upregulated and associated with increased store-operated Ca2+ entry (SOCE), whereas contractile-state cells show increased voltage-dependent Ca2+ entry; knockdown/functional data indicate STIM2 and Orai2 upregulation drives phenotypic transition to a proliferative state.\",\n      \"method\": \"Quantitative PCR, Western blot, Ca2+ imaging (SOCE assay), siRNA knockdown in PASMC phenotype switch model\",\n      \"journal\": \"American journal of physiology. Cell physiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — multiple methods (qPCR, Western, Ca2+ imaging) in a defined phenotypic model, but mechanistic pathway placement is correlative without rigorous epistasis\",\n      \"pmids\": [\"25673771\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"ORAI2 is a central mediator of neuronal capacitative Ca2+ entry; Orai2-deficient neurons show significantly diminished Ca2+ signals induced by store depletion or oxygen/glucose deprivation, and Orai2-deficient mice are protected from ischemic neuronal death during acute stroke and ischemia/reperfusion.\",\n      \"method\": \"Genetic knockout mouse, Ca2+ imaging in primary neurons (store depletion and OGD), middle cerebral artery occlusion experimental stroke model\",\n      \"journal\": \"Stroke\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean genetic KO with direct Ca2+ imaging in neurons and in vivo stroke model; multiple functional readouts in one study\",\n      \"pmids\": [\"31551038\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"ORAI2 expression is specifically upregulated at the G2/M phase of the cell cycle in brain capillary endothelial cells; at this phase, increased ORAI2 negatively modulates SOCE activity, and knockdown of ORAI2 at G2/M removes this SOCE decrease and partly attenuates cell proliferation.\",\n      \"method\": \"Cell synchronization by double thymidine blockage, qPCR and Western blot, siRNA knockdown, Ca2+ imaging (SOCE assay), cell proliferation assay\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — synchronized cell cycle with multiple methods; single lab but orthogonal approaches linking ORAI2 expression, SOCE, and proliferation\",\n      \"pmids\": [\"25748572\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"ORAI2 contributes to SOCE in HL60 leukemia cells; Orai2 silencing significantly attenuates thapsigargin-induced SOCE, and combined silencing of Orai1 and Orai2 nearly abolishes SOCE; knockdown of Orai1 and Orai2 impairs HL60 cell migration in vitro, associated with impaired FAK tyrosine phosphorylation.\",\n      \"method\": \"siRNA knockdown, fluorescence Ca2+ imaging, transwell migration assay, Western blot for FAK phosphorylation\",\n      \"journal\": \"Biochimica et biophysica acta. Molecular cell research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — siRNA knockdown with Ca2+ imaging, migration assay, and FAK phosphorylation readout; single lab, multiple methods\",\n      \"pmids\": [\"27865925\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"ORAI2 mediates store-operated Ca2+ entry and promotes gastric cancer cell proliferation, migration, tumor formation and metastasis; mechanistically, ORAI2-mediated SOC activity activates PI3K/Akt signaling and enhances FAK-mediated MAPK/ERK activation, promoting focal adhesion disassembly at the rear edge of migrating cells.\",\n      \"method\": \"Gain- and loss-of-function (overexpression and siRNA/shRNA knockdown) in gastric cancer cell lines and xenograft mouse models; Ca2+ imaging, Western blot for PI3K/Akt and FAK/MAPK/ERK, focal adhesion assays\",\n      \"journal\": \"Cancer research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal gain/loss-of-function with in vivo xenograft and multiple signaling pathway readouts; single lab\",\n      \"pmids\": [\"33310726\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"ORAI2 is the primary pore subunit mediating capacitative Ca2+ entry in murine neutrophils; ORAI2-deficient neutrophils show decreased (not increased) Ca2+ influx, contrasting with enhanced SOCE seen in other immune cell types lacking ORAI2; this decreased SOCE in ORAI2-deficient neutrophils is correlated with altered KCa3.1-mediated membrane potential regulation.\",\n      \"method\": \"Genetic KO mouse (Orai1-/-, Orai2-/-, double KO), Ca2+ imaging, patch-clamp, membrane potential measurements, neutrophil functional assays (phagocytosis, degranulation, ROS, leukotriene), in vivo staphylococcal infection model\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean genetic KO with multiple orthogonal methods and mechanistic link to KCa3.1 membrane potential; single lab but rigorous\",\n      \"pmids\": [\"32929002\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"LRRK2 kinase activity negatively regulates ORAI2 expression in dendritic cells; LRRK2 deficiency increases ORAI2 expression (but not ORAI1 or ORAI3) and enhances DC migration; silencing ORAI2 markedly decreases DC migration without affecting maturation markers, whereas ORAI1 silencing affects both migration and maturation markers.\",\n      \"method\": \"Genetic KO (LRRK2-/- mice), pharmacological LRRK2 kinase inhibition, siRNA knockdown of ORAI1/2/3, Ca2+ imaging, transwell migration assay, flow cytometry for maturation markers\",\n      \"journal\": \"FASEB journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic and pharmacological tools with specific isoform knockdown revealing selective ORAI2 regulation by LRRK2; single lab\",\n      \"pmids\": [\"31166814\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"ORAI2 amplitude of CRAC current (ICRAC) is sensitive to changes in intracellular pH similarly to ORAI1, but unlike ORAI1, fast Ca2+-dependent inactivation kinetics of ORAI2 are unaffected by acidic intracellular pH; ORAI3-mediated ICRAC shows no pH dependence.\",\n      \"method\": \"Whole-cell patch-clamp of HEK293T cells heterologously expressing ORAI isoforms with STIM1, intracellular pH manipulation, Orai1-Orai3 chimera domain-swap analysis\",\n      \"journal\": \"The Journal of physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — direct electrophysiological characterization with chimeric constructs and pH clamping; rigorous biophysical dissection in a single study\",\n      \"pmids\": [\"34877682\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"ORAI2 negatively modulates SOCE in astrocytes; Orai2 knockdown or knockout increases SOCE and Orai1 expression, and augments production of prostaglandin E2 (via upregulated Ptges and Ptgs2) in TNFα/IL1α-stimulated astrocytes, demonstrating that ORAI2 restrains inflammatory PGE2 production in the CNS.\",\n      \"method\": \"siRNA knockdown and genetic KO (Orai2-KO) in primary astrocytes, Ca2+ imaging, qPCR and Western blot for Ptges/Ptgs2/Orai1, PGE2 ELISA\",\n      \"journal\": \"Glia\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic KO confirmed with siRNA knockdown, multiple readouts linking ORAI2 to SOCE and PGE2 pathway; single lab\",\n      \"pmids\": [\"35506586\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"NSUN2-mediated m5C modification of ORAI2 mRNA increases its stability and expression; YBX1 acts as the 'reader' of this m5C modification site; upstream, fatty acids from omental adipocytes activate the AMPK pathway to upregulate E2F1, which promotes NSUN2 transcription, thereby driving ORAI2 expression and gastric cancer peritoneal metastasis.\",\n      \"method\": \"RNA bisulfite sequencing (m5C mapping), RIP (RNA immunoprecipitation) for NSUN2 and YBX1, mRNA stability assay, ChIP for E2F1 on NSUN2 promoter, functional colonization/metastasis assays\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple biochemical methods (m5C mapping, RIP, ChIP) establishing post-transcriptional regulation; single lab\",\n      \"pmids\": [\"37130916\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"ORAI2 mediates a SOCE-dependent signaling axis (ORAI2/JNK/NFAT1) that drives TGF-β1-mediated fibrogenesis in irradiated salivary glands; inhibition of SOCE reduces fibrosis in an ORAI2-dependent manner, and pharmacological inhibition of NFAT1 restores saliva flow to ~85% of normal in irradiated mice.\",\n      \"method\": \"RNA sequencing of irradiated mouse salivary glands, SOCE inhibition (SKF96365, YM58483), siRNA/KO of ORAI2, Western blot for JNK/NFAT1/TGF-β1, in vivo irradiation model with pharmacological NFAT1 inhibition\",\n      \"journal\": \"International journal of radiation oncology, biology, physics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic and pharmacological tools with in vivo validation; ORAI2/JNK/NFAT1/TGF-β1 pathway placed by multiple orthogonal methods in single lab\",\n      \"pmids\": [\"39384103\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"ORAI2 downregulation in human neuroglioma H4 cells significantly increases SOCE amplitude; in Aβ-secreting H4-APPswe cells, ORAI2 downregulation (increased SOCE) decreases Aβ42 accumulation, whereas SOCE inhibition increases Aβ42 accumulation, establishing that ORAI2 negatively regulates SOCE and thereby modulates amyloid-beta production.\",\n      \"method\": \"siRNA knockdown and overexpression, Ca2+ imaging (SOCE measurement), SOCE inhibitor (BTP2), Aβ42 ELISA in H4-APPswe cells\",\n      \"journal\": \"International journal of molecular sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — reciprocal gain/loss-of-function with functional Ca2+ and Aβ42 readouts, but single lab and single cell line model\",\n      \"pmids\": [\"32722509\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"ORAI2 is a pore-forming subunit of Ca2+ release-activated Ca2+ (CRAC) channels that requires STIM1 for activation; it preferentially forms heteromeric channels with ORAI1 to attenuate the magnitude of store-operated Ca2+ entry (SOCE) in most cell types (T cells, mast cells, astrocytes, chondrocytes), though in neutrophils it contributes positively to SOCE via a KCa3.1-dependent membrane potential mechanism; ORAI2-mediated SOCE regulates diverse downstream processes including NFAT activation, PI3K/Akt and FAK/MAPK/ERK signaling, PGE2 production, neuronal Ca2+ overload during ischemia, and cell cycle progression, with its expression controlled post-transcriptionally by NSUN2-mediated m5C mRNA modification.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"ORAI2 is a pore-forming subunit of store-operated Ca2+ release-activated Ca2+ (CRAC) channels that, together with STIM1, conducts Ca2+-selective currents upon store depletion, with intrinsic conductance efficacy ranking ORAI1 > ORAI2 > ORAI3 [#0]. In most cell types ORAI2 assembles into hetero-oligomeric (likely hetero-tetrameric) channels with ORAI1, where it acts as a negative rheostat: overexpression lowers and loss-of-function raises store-operated Ca2+ entry (SOCE), as demonstrated by single-molecule coupling in chondrocytes and reciprocal knockout phenotypes in T cells [#2, #3]. This attenuating role is conserved across mast cells, astrocytes, and neuroglioma, where ORAI2 deletion or knockdown augments CRAC currents and amplifies downstream Ca2+-dependent outputs including mast cell degranulation and anaphylaxis, astrocytic PGE2 production, and amyloid-beta handling [#4, #14, #17]. A second ORAI2 splice variant (ORAI2S) displays strong Ca2+-dependent inactivation and a dominant-negative effect on channel assembly, providing an additional layer of conductance tuning [#1]. In specific cellular contexts ORAI2 instead serves as the primary positive driver of SOCE: it is the dominant pore subunit in neutrophils, where its loss decreases Ca2+ influx through a KCa3.1-dependent membrane-potential mechanism, and it sustains capacitative entry in neurons, where Orai2 deficiency protects against ischemic neuronal death [#11, #7]. ORAI2-mediated SOCE feeds defined signaling axes that govern proliferation, migration, and pathology — activating PI3K/Akt and FAK/MAPK/ERK to promote gastric cancer growth and metastasis, and an ORAI2/JNK/NFAT1 axis driving TGF-beta1-mediated salivary gland fibrosis [#10, #16]. ORAI2 expression is itself regulated post-transcriptionally by NSUN2-mediated m5C modification of its mRNA, read by YBX1 to enhance transcript stability [#15], and is cell-cycle-dependent, peaking at G2/M to restrain SOCE [#8].\",\n  \"teleology\": [\n    {\n      \"year\": 2006,\n      \"claim\": \"Established that ORAI2 is not merely an ORAI1 homolog but an autonomous pore-forming CRAC channel subunit, answering whether it could conduct store-operated Ca2+ current at all.\",\n      \"evidence\": \"Co-transfection of ORAI2 with STIM1 in HEK293 cells and electrophysiological recording of Ca2+-selective store-operated currents\",\n      \"pmids\": [\"16807233\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not address ORAI2 behavior in heteromeric channels with ORAI1\", \"Quantitative efficacy ranking measured only in heterologous overexpression\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Revealed splice-variant and cell-background control of ORAI2 channel function, showing ORAI2S can act dominant-negatively on CRAC assembly and adding a tuning mechanism beyond simple expression level.\",\n      \"evidence\": \"Cloning of murine ORAI2L/ORAI2S splice variants, expression with STIM1 in HEK293 and RBL 2H3 cells, whole-cell patch-clamp\",\n      \"pmids\": [\"17463004\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Functional difference between HEK293 and RBL 2H3 not mechanistically explained\", \"Physiological relevance of ORAI2S dominant-negative effect in native cells not established\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Proposed a non-canonical localization of ORAI2 on secretory granules and a role in antigen-specific Ca2+ mobilization, distinct from a purely plasma-membrane channel function.\",\n      \"evidence\": \"Subcellular fractionation, immunofluorescence, siRNA knockdown, Ca2+ imaging and exocytosis assay in RBL-2H3 mast cells\",\n      \"pmids\": [\"25044118\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Granular localization shown by fractionation/immunofluorescence only, no reconstitution of granule channel activity\", \"Single cell line; not confirmed in primary mast cells\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Defined ORAI2 as a negative modulator within ORAI1-ORAI2 heteromeric channels, answering how it shapes SOCE magnitude rather than simply adding conductance.\",\n      \"evidence\": \"Single-molecule TIRF imaging of ORAI1-ORAI2 coupling plus reciprocal knockdown/overexpression and Ca2+ imaging in chondrocytes\",\n      \"pmids\": [\"25769459\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Exact stoichiometry of the hetero-oligomer not resolved\", \"Whether attenuation arises from altered gating or reduced ORAI1 incorporation not determined\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Linked ORAI2 expression and SOCE to cell-state transitions and proliferation, beginning to connect channel function to physiological outcomes.\",\n      \"evidence\": \"qPCR, Western blot, Ca2+ imaging and siRNA knockdown in pulmonary arterial smooth muscle and brain capillary endothelial cell-cycle models\",\n      \"pmids\": [\"25673771\", \"25748572\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Pathway placement largely correlative without epistasis\", \"Cell-cycle-dependent upregulation mechanism at G2/M not defined\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Provided definitive in vivo genetic proof that ORAI2 attenuates CRAC function in immune cells, with reciprocal SOCE phenotypes for Orai1 vs Orai2 deletion and physiological consequences for T cell and mast cell biology.\",\n      \"evidence\": \"Orai1, Orai2 single and double knockout mice with CRAC electrophysiology, Ca2+ imaging, Co-IP/FRET, and in vivo immune and anaphylaxis models\",\n      \"pmids\": [\"28294127\", \"29604961\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular basis of the attenuating effect within native heteromers not resolved\", \"Tissue-specific expression ratios governing the degree of attenuation not quantified\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Showed ORAI2 can be the dominant positive mediator of SOCE in specific lineages, overturning a uniform attenuator model; established neuronal and dendritic-cell roles and a regulatory link to LRRK2.\",\n      \"evidence\": \"Orai2 knockout neurons and mice with Ca2+ imaging and stroke models; LRRK2-KO/inhibitor with isoform-specific siRNA and migration assays\",\n      \"pmids\": [\"31551038\", \"31166814\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Why ORAI2 is positive in neurons but attenuating elsewhere not mechanistically explained\", \"Mechanism by which LRRK2 kinase activity selectively suppresses ORAI2 expression unknown\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Resolved the context-dependence by identifying a KCa3.1-dependent membrane-potential mechanism that makes ORAI2 the primary positive SOCE driver in neutrophils, and connected ORAI2 SOCE to oncogenic PI3K/Akt and FAK/MAPK/ERK signaling in cancer.\",\n      \"evidence\": \"Neutrophil knockout mice with patch-clamp and membrane-potential measurements; gain/loss-of-function in gastric cancer lines and xenografts with signaling readouts\",\n      \"pmids\": [\"32929002\", \"33310726\", \"27865925\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How KCa3.1 coupling differs between neutrophils and attenuator cell types not defined\", \"Direct biochemical link between ORAI2 channel activity and PI3K/FAK activation not established\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Distinguished ORAI2 biophysically from its homologs and extended its negative-regulatory role to amyloid-beta production, refining isoform-specific channel properties.\",\n      \"evidence\": \"Whole-cell patch-clamp with pH manipulation and ORAI1-ORAI3 chimeras; siRNA/overexpression with Abeta42 ELISA in H4-APPswe cells\",\n      \"pmids\": [\"34877682\", \"32722509\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural determinant of ORAI2 pH-insensitive inactivation not mapped to specific residues\", \"Abeta findings limited to a single neuroglioma cell line\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Demonstrated ORAI2 restrains inflammatory and fibrotic Ca2+-dependent programs, linking it to CNS PGE2 production and to a JNK/NFAT1/TGF-beta1 fibrogenic axis with therapeutic relevance.\",\n      \"evidence\": \"Astrocyte siRNA/KO with Ca2+ imaging, qPCR/Western and PGE2 ELISA; irradiated salivary gland model with SOCE/NFAT1 inhibition and ORAI2 KO\",\n      \"pmids\": [\"35506586\", \"39384103\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether ORAI2-PGE2 and ORAI2-fibrosis effects are direct channel functions or secondary to ORAI1 upregulation not separated\", \"NFAT1 activation mechanism downstream of ORAI2 in fibroblasts not detailed\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Identified the upstream post-transcriptional control of ORAI2 abundance, explaining how its expression is tuned in disease via an NSUN2/m5C/YBX1 axis.\",\n      \"evidence\": \"RNA bisulfite sequencing, RIP for NSUN2/YBX1, mRNA stability assays, E2F1 ChIP and metastasis assays in gastric cancer\",\n      \"pmids\": [\"37130916\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether m5C regulation of ORAI2 operates outside gastric cancer not tested\", \"Single lab; YBX1-dependent stabilization not reconstituted in vitro\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The molecular determinant that switches ORAI2 between attenuator (T cells, mast cells, astrocytes) and primary positive conductor (neutrophils, neurons) remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structural model of native ORAI1-ORAI2 heteromer stoichiometry across cell types\", \"Relative ORAI1/ORAI2/STIM expression ratios that dictate sign of the effect not systematically mapped\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0005215\", \"supporting_discovery_ids\": [0, 1, 3, 11, 13]},\n      {\"term_id\": \"GO:0005262\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [0, 2, 3]},\n      {\"term_id\": \"GO:0031410\", \"supporting_discovery_ids\": [5]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [3, 10, 16]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [3, 4, 11]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [7, 10, 16, 17]}\n    ],\n    \"complexes\": [\"ORAI1-ORAI2 heteromeric CRAC channel\"],\n    \"partners\": [\"ORAI1\", \"STIM1\", \"STIM2\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":7,"faith_total":7,"faith_pct":100.0}}