{"gene":"AHCYL1","run_date":"2026-04-28T17:12:37","timeline":{"discoveries":[{"year":2003,"finding":"IRBIT (AHCYL1) was identified as a novel IP3 receptor type 1 (IP3R1)-binding protein that is released from IP3R1 upon IP3 binding. The N-terminal region of IRBIT is essential for the interaction, and the IRBIT binding region on IP3R1 was mapped to the IP3 binding core. Alkaline phosphatase treatment abolished the interaction, indicating that phosphorylation of IRBIT is required for binding.","method":"Affinity purification, in vitro binding assays, co-immunoprecipitation, alkaline phosphatase treatment","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1-2 — multiple orthogonal methods, foundational discovery paper with high citation count","pmids":["12525476"],"is_preprint":false},{"year":2006,"finding":"IRBIT competes with IP3 for the common binding site on IP3R, suppressing IP3R activation. Multiserine phosphorylation of IRBIT is essential for binding to IP3R, and 10 of 12 key amino acids in IP3R for IP3 recognition also participate in IRBIT binding, establishing IRBIT as an endogenous pseudoligand of IP3R.","method":"[3H]IP3 binding assays, in vitro Ca2+ release assays, Ca2+ imaging in intact cells, mutagenesis","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 1 — reconstitution assays plus mutagenesis plus cell imaging, high citation count","pmids":["16793548"],"is_preprint":false},{"year":2006,"finding":"IRBIT directly interacts with IP3R, requiring both the suppressor domain and the IP3-binding core of IP3R for strong interaction. A PEST motif and PDZ-ligand on IRBIT are critical for IP3R interaction, and Asp-73 is a critical residue. IRBIT inhibits both IP3 binding and IP3-induced Ca2+ release.","method":"Direct binding assays, deletion and point mutagenesis, IP3 binding competition, Ca2+ release assays","journal":"Biochemical and biophysical research communications","confidence":"High","confidence_rationale":"Tier 1-2 — direct binding with mutagenesis, consistent with independent reports","pmids":["16527252"],"is_preprint":false},{"year":2006,"finding":"IRBIT specifically binds to the pancreas-type NBC1 (pNBC1) but not kidney-type NBC1 (kNBC1), through the N-terminal pNBC1-specific domain. IRBIT binding depends on phosphorylation of multiple serine residues of IRBIT. Co-expression of IRBIT in Xenopus oocytes is required for pNBC1 to manifest substantial electrogenic activity, revealing IRBIT as an activator of pNBC1.","method":"Co-immunoprecipitation, two-electrode voltage clamp in Xenopus oocytes, mutagenesis","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1-2 — electrophysiology plus binding assays, high citation count, replicated by subsequent studies","pmids":["16769890"],"is_preprint":false},{"year":2007,"finding":"Protein phosphatase-1 (PP1) binds to a conserved PP1-binding site on IRBIT (preceding the PEST domain), dephosphorylates Ser68 of IRBIT, and thereby reduces IRBIT's affinity for IP3R. Phosphorylation of Ser68 is required for subsequent phosphorylation of Ser71 and Ser74, and Ser71/Ser74 phosphorylation is sufficient to enable IRBIT-mediated inhibition of IP3 binding. IRBIT thus acts as a substrate specifier for PP1.","method":"In vitro binding assays, mass spectrometry, site-directed mutagenesis, phosphatase assays, Co-IP","journal":"The Biochemical journal","confidence":"High","confidence_rationale":"Tier 1-2 — multiple orthogonal methods including in vitro kinase/phosphatase assays and mutagenesis","pmids":["17635105"],"is_preprint":false},{"year":2008,"finding":"IRBIT activates both basolateral pNBC1 and luminal CFTR in pancreatic duct to coordinate fluid and HCO3- secretion. siRNA knockdown of IRBIT markedly inhibited ductal pNBC1 and CFTR activities, luminal Cl- absorption, HCO3- secretion, and fluid secretion. IRBIT activates pNBC1 via the PEST domain alone, while activation of CFTR requires multiple IRBIT domains, indicating distinct mechanisms.","method":"siRNA knockdown, video microscopy, ion-selective microelectrodes, single-channel recordings, expression of IRBIT domain constructs in HEK cells","journal":"The Journal of clinical investigation","confidence":"High","confidence_rationale":"Tier 2 — multiple physiological assays plus domain dissection, high citation count","pmids":["19033647"],"is_preprint":false},{"year":2008,"finding":"IRBIT binds to the C-terminal domain of NHE3 and activates NHE3 activity in a Ca2+-dependent manner. IRBIT-dependent activation of NHE3 involves exocytic trafficking of NHE3 to the plasma membrane, requires calmodulin and CaMKII, and can reverse NHERF2-dependent inhibition of NHE3.","method":"Co-immunoprecipitation, ectopic expression, siRNA knockdown, NHE3 activity assays, cell surface biotinylation, pharmacological inhibition","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 — multiple complementary methods establishing binding, trafficking and functional outcome","pmids":["18829453"],"is_preprint":false},{"year":2009,"finding":"IRBIT interacts with CPSF (cleavage and polyadenylation specificity factor), with the primary target being Fip1 subunit, in a phosphorylation-dependent manner. IRBIT is recruited to polyadenylation signal-containing RNA. Phosphorylation of IRBIT's serine-rich region promotes cytoplasmic redistribution of Fip1. IRBIT also binds poly(A) polymerase (PAP) and inhibits PAP activity in a phosphorylation-dependent manner.","method":"Co-immunoprecipitation, in vitro binding assays, RNA pulldown, PAP activity assay, immunofluorescence","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1-2 — in vitro enzymatic assay plus multiple binding and localization methods","pmids":["19224921"],"is_preprint":false},{"year":2009,"finding":"Long-IRBIT (AHCYL2), an IRBIT homologue, heteromerizes with IRBIT but retains little ability to interact with IP3R despite conserving critical amino acids. The unique N-terminal appendage (LISN domain) of Long-IRBIT inhibits its interaction with IP3R. Long-IRBIT and IRBIT show distinct distributions in mouse cerebellar cortex.","method":"Co-immunoprecipitation, deletion mutagenesis, immunohistochemistry","journal":"Journal of neurochemistry","confidence":"Medium","confidence_rationale":"Tier 2-3 — Co-IP and mutagenesis in a single study","pmids":["19220705"],"is_preprint":false},{"year":2010,"finding":"IRBIT mediates angiotensin II (ANG II)-induced activation of NHE3 via CaMKII-dependent phosphorylation. ANG II transiently increases IRBIT binding to NHE3, and inhibition of CaMKII blocks both ANG II-induced IRBIT-NHE3 binding and NHE3 surface abundance. Mutations of Ser-68, Ser-71, and Ser-74 of IRBIT decreased binding to NHE3 and reduced NHE3 activity.","method":"siRNA knockdown, overexpression, co-immunoprecipitation, NHE3 activity assays, CaMKII inhibition, site-directed mutagenesis","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods linking IRBIT phosphorylation to NHE3 regulation","pmids":["20584908"],"is_preprint":false},{"year":2011,"finding":"IRBIT activates NBCe1-B (pNBC1) by relieving autoinhibition. Deletion of the autoinhibitory domain (AID, residues ~1-87) stimulates NBCe1-B to the same extent as coexpression of wild-type IRBIT. An NBCe1-B construct lacking residues 2-16 is fully autoinhibited but cannot be stimulated by IRBIT, indicating IRBIT-binding and autoinhibitory determinants are distinct but overlapping.","method":"Two-electrode voltage clamp in Xenopus oocytes, deletion mutagenesis","journal":"American journal of physiology. Cell physiology","confidence":"High","confidence_rationale":"Tier 1-2 — electrophysiology with systematic mutagenesis","pmids":["22012331"],"is_preprint":false},{"year":2011,"finding":"IRBIT governs epithelial secretion by antagonizing the WNK/SPAK kinase pathway. WNK kinases act as scaffolds to recruit SPAK, which phosphorylates CFTR and NBCe1-B, reducing their cell surface expression. IRBIT opposes this by recruiting PP1 to the complex to dephosphorylate CFTR and NBCe1-B, restoring their surface expression and activity. Silencing of both SPAK and IRBIT rescues the secretion defect caused by IRBIT silencing alone.","method":"siRNA knockdown, phosphoprotein analysis, co-immunoprecipitation, epithelial secretion assays, genetic epistasis","journal":"The Journal of clinical investigation","confidence":"High","confidence_rationale":"Tier 2 — epistasis plus multiple molecular methods across independent labs","pmids":["21317537"],"is_preprint":false},{"year":2012,"finding":"IRBIT interacts with the Cl-/HCO3- exchanger AE2; IRBIT binding facilitates lysosomal degradation of AE2, while coexisting L-IRBIT inhibits this degradation, resulting in opposing regulation of AE2 expression and activity. This affects regulatory volume increase and cell migration.","method":"Co-immunoprecipitation, KO cell lines, AE2 activity assays, lysosome inhibitor (bafilomycin A1), cell migration assays","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 2-3 — KO cells with multiple assays but single study","pmids":["33727633"],"is_preprint":false},{"year":2013,"finding":"IRBIT mediates synergy between Ca2+ and cAMP signaling pathways in pancreatic and salivary duct epithelial cells. cAMP-induced phosphorylation of IP3Rs reduces their affinity for Irbit, allowing weak IP3 production to release Irbit from IP3Rs; Irbit then translocates to CFTR and Slc26a6 in the plasma membrane to stimulate secretion. This synergy was absent in Irbit-/- and Slc26a6-/- mice and in mice with IP3Rs mutated at PKA phosphorylation sites.","method":"Knockout mouse models, immunoprecipitation, intracellular pH measurements, Cl- current recordings, fluid secretion assays, genetic epistasis","journal":"Gastroenterology","confidence":"High","confidence_rationale":"Tier 2 — multiple KO models, orthogonal functional assays, genetic epistasis","pmids":["23542070"],"is_preprint":false},{"year":2013,"finding":"A conserved positively charged module within NBCe1-B (residues 37-65) is required for interaction and activation of NBCe1-B and NBCn1-A by IRBIT and for regulation by PIP2. IRBIT and PIP2 activate these transporters in a nonadditive but complementary manner. Phosphorylation of Ser65 mediates SPAK regulation while Thr49 is required for IRBIT and SPAK regulation. The same regulatory module was identified in CFTR R domain and Slc26a6 STAS domain, and IRBIT binds these domains.","method":"Mutagenesis, Co-IP, electrophysiology in Xenopus oocytes","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1-2 — mutagenesis plus electrophysiology plus binding assays across multiple transporters","pmids":["23431199"],"is_preprint":false},{"year":2014,"finding":"IRBIT forms a deoxyadenosine triphosphate (dATP)-dependent complex with ribonucleotide reductase (RNR) in metazoans, stabilizing dATP in the activity site of RNR and inhibiting the enzyme. Formation of the RNR-IRBIT complex is regulated by phosphorylation of IRBIT. Ablation of IRBIT in HeLa cells causes imbalanced dNTP pools and altered cell cycle progression.","method":"Co-immunoprecipitation, in vitro RNR activity assays, phosphorylation analysis, dNTP pool measurement, cell cycle analysis in IRBIT-depleted cells","journal":"Science (New York, N.Y.)","confidence":"High","confidence_rationale":"Tier 1-2 — biochemical reconstitution with in vitro enzyme assays plus cell-based phenotype","pmids":["25237103"],"is_preprint":false},{"year":2015,"finding":"IRBIT binds CaMKIIα and suppresses its kinase activity by inhibiting calmodulin binding to CaMKIIα. In IRBIT-deficient mice, TH phosphorylation by CaMKIIα is increased in the ventral tegmental area, leading to elevated catecholamine levels, increased locomotor activity, and social abnormalities.","method":"Co-immunoprecipitation, kinase activity assays, IRBIT-deficient mice, behavioral analysis, phosphorylation assays","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 — biochemical binding/kinase assays plus in vivo KO phenotype","pmids":["25922519"],"is_preprint":false},{"year":2015,"finding":"IRBIT interacts with all PIPK isoforms in heterologous systems and specifically with PIPKIα and PIPKIIα in mouse cerebellum. Two conserved catalytic aspartate residues of PIPKIα and PIPKIIα are required for IRBIT binding. Phosphatidylinositol 4-phosphate, Mg2+, and/or ATP interfere with the interaction. Mutations in the serine-rich region of IRBIT affect selectivity for PIPKIα versus PIPKIIα. IRBIT, PIPKIα, and NBCe1-B form a signaling complex.","method":"Co-immunoprecipitation, in vitro binding assays, site-directed mutagenesis, immunocytochemistry","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2-3 — mutagenesis plus binding assays, single study","pmids":["26509711"],"is_preprint":false},{"year":2016,"finding":"IRBIT interacts with the Bcl-2 homolog Bcl2l10, and together they exert additive inhibition of IP3R in the physiological state. IRBIT and Bcl2l10 associate in mitochondria-associated membranes (MAMs). Upon apoptotic stress, IRBIT is dephosphorylated and becomes an inhibitor of Bcl2l10; IRBIT also promotes ER-mitochondria contact, facilitating massive Ca2+ transfer to mitochondria and promoting apoptosis.","method":"Co-immunoprecipitation, fractionation (MAM isolation), Ca2+ release assays, apoptosis assays, dephosphorylation studies","journal":"eLife","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods including subcellular fractionation, functional assays, and mechanistic dissection","pmids":["27995898"],"is_preprint":false},{"year":2016,"finding":"NHERF1 PDZ1 domain interacts with IRBIT and is required for ANG II-mediated forward trafficking and activation of NHE3. IRBIT phosphorylation at Ser68 is necessary for assembly of the NHERF1-IRBIT-NHE3 complex, and IRBIT is indispensable for ANG II-induced increase in NHERF1-NHE3 interaction.","method":"Co-immunoprecipitation, overexpression of dominant negative constructs, surface NHE3 quantification, site-directed mutagenesis","journal":"American journal of physiology. Renal physiology","confidence":"Medium","confidence_rationale":"Tier 2-3 — multiple binding and functional assays in a single study","pmids":["27279487"],"is_preprint":false},{"year":2017,"finding":"IRBIT and Long-IRBIT form homo- and heteromultimers. N-terminal splicing of Long-IRBIT changes protein stability and selectivity toward target molecules. Different combinations of IRBIT family multimers contribute to functional diversity.","method":"Co-immunoprecipitation, expression analysis in multiple tissues, mutagenesis of N-terminal regions","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"Medium","confidence_rationale":"Tier 3 — Co-IP and expression profiling, single study","pmids":["28348216"],"is_preprint":false},{"year":2018,"finding":"IRBIT recruits PP1 and SPAK to control phosphorylation of Ser65 in NBCe1-B, affecting Cl-in sensing by the 32GXXXP36 motif. IRBIT also recruits calcineurin and CaMKII to control phosphorylation of Ser12, affecting Cl-in sensing by 194GXXXP198. Phosphorylation of Ser232, Ser233, and Ser235 determines the active vs. inactive conformation of NBCe1-B, with the pSer233/pSer235 form mimicking IRBIT-activated NBCe1-B but insensitive to Cl-in inhibition.","method":"Phosphoproteomic analysis, mutagenesis, electrophysiology, co-immunoprecipitation","journal":"Science signaling","confidence":"High","confidence_rationale":"Tier 1-2 — phosphoproteomics plus systematic mutagenesis and electrophysiology","pmids":["30377224"],"is_preprint":false},{"year":2020,"finding":"IRBIT activates NBCe1-B by releasing the autoinhibitory domain (AID) from the transmembrane domain. The AID (residues 40-85) acts as a brake binding the transmembrane domain via electrostatic interaction; IRBIT competitively binds the AID to release this brake. The IRBIT-binding domain of NBCe1-B consists of negatively charged (residues 1-24) and positively charged (residues 40-52) arms. Negatively charged Asp/Glu residues plus Ser/Thr residues in IRBIT PEST domain are required for NBCe1-B interaction.","method":"Electrophysiology (Xenopus oocytes), systematic mutagenesis, charge manipulation experiments","journal":"The Journal of physiology","confidence":"High","confidence_rationale":"Tier 1 — systematic mutagenesis with electrophysiology establishing molecular mechanism","pmids":["33237573"],"is_preprint":false},{"year":2020,"finding":"IRBIT regulates ribonucleotide reductase (RNR) activity in Drosophila ISC progeny, and IRBIT expression directs differentiation of intestinal stem cell progeny by suppressing RNR activity. Disruption of the IRBIT-RNR circuit causes premature loss of intestinal tissue integrity; age-related dysplasia can be reversed by suppressing RNR in ISC progeny.","method":"Genetic loss-of-function in Drosophila, tissue histology, RNR activity assays","journal":"iScience","confidence":"Medium","confidence_rationale":"Tier 2 — Drosophila ortholog with genetic and functional validation, consistent with mammalian RNR regulation","pmids":["32179478"],"is_preprint":false},{"year":2020,"finding":"IRBIT stabilizes NBCn1 transporter expression in the plasma membrane and enhances cancer cell migration. Overexpression of IRBIT enhanced NBCn1 activity and cell migration; knockdown of IRBIT or NBCn1 attenuated cell migration. EGF signaling recruits IRBIT to maintain NBCn1 in the plasma membrane.","method":"Overexpression, siRNA knockdown, NBC activity assays, cell migration assays, surface protein analysis","journal":"Pharmaceutics","confidence":"Medium","confidence_rationale":"Tier 3 — functional assays in cancer cells, single study","pmids":["32867284"],"is_preprint":false},{"year":2021,"finding":"AHCYL1 (IRBIT) functions as a SAH (S-adenosyl-L-homocysteine) sensor to inhibit autophagy through PIK3C3. The C-terminus of AHCYL1 specifically binds SAH, and this interaction promotes binding of the N-terminus to the catalytic domain of PIK3C3, inhibiting PIK3C3 activity and thus suppressing autophagy in an MTORC1-independent manner.","method":"Co-immunoprecipitation, PIK3C3 activity assays, autophagy assays, SAH binding experiments, in vivo validation","journal":"Autophagy","confidence":"High","confidence_rationale":"Tier 1-2 — enzymatic assay plus binding domain mapping plus in vivo validation","pmids":["33993848"],"is_preprint":false},{"year":2022,"finding":"IRBIT physically interacts with microtubule-associated protein tau in brain tissues and cultured cells. Tau overexpression modifies the close localization of AHCYL1/IRBIT to IP3R at the endoplasmic reticulum, as shown by proximity ligation assay.","method":"Protein microarray, co-immunoprecipitation, proximity ligation assay","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 3 — Co-IP and proximity ligation, single study, no functional mechanism established","pmids":["35218773"],"is_preprint":false},{"year":2022,"finding":"IRBIT knockout in INS-1 cells reduces insulin content and glucose-stimulated insulin secretion, reduces INS2 mRNA levels, and increases nuclear localization of AHCY. In RyR2 KO cells, IRBIT protein levels are reduced, suggesting RyR2 maintains IRBIT levels. IRBIT and RyR2 deletion causes increased exon 2 methylation of insulin genes.","method":"CRISPR knockout, insulin secretion assays, qPCR, nuclear fractionation, DNA methylation analysis, proteomics","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 2-3 — KO phenotype with multiple readouts but mechanistic link is partial","pmids":["35562179"],"is_preprint":false},{"year":2024,"finding":"AHCYL1 deficiency in NRAS-mutant melanoma results in decreased ER calcium levels, activation of the unfolded protein response (UPR), and downstream apoptosis. AHCYL1 transcription in NRAS-mutated melanoma is regulated by ATF2. AHCYL1 is selectively upregulated and required for cell proliferation specifically in NRAS-mutated (not BRAF V600E) melanoma.","method":"RNAi screen, AHCYL1 knockdown, Ca2+ measurements, UPR assays, apoptosis assays, xenograft models","journal":"Molecular cancer research : MCR","confidence":"Medium","confidence_rationale":"Tier 2-3 — functional knockdown with multiple readouts but mechanistic dissection limited","pmids":["38294692"],"is_preprint":false},{"year":2025,"finding":"IRBIT activates NBCe1-B in a NAD redox state-dependent manner; IRBIT and L-IRBIT serve as NAD cofactors, with NAD+ enhancing and NADH decreasing NBCe1-B activity. Blocking the NAD salvage pathway greatly decreases NBCe1-B activation by the IRBITs, establishing NAD redox state as a modulator of IRBIT-dependent transporter regulation.","method":"Electrophysiology, pharmacological inhibition of NAD salvage pathway, NAD+/NADH administration","journal":"Science China. Life sciences","confidence":"Medium","confidence_rationale":"Tier 2 — functional assays with pharmacological tools, single study","pmids":["39985648"],"is_preprint":false},{"year":2025,"finding":"AHCYL1 enhances PREX2 GEF (guanine nucleotide exchange factor) activity toward RAC1 by alleviating mutual inhibition between PREX2 and PTEN, thereby intensifying tumor-promoting effects of PREX2 in NSCLC. AHCYL1 was identified as a novel PREX2-interacting protein.","method":"Pull-down assay, LC-MS/MS, in vitro GEF assay, active RAC1 pulldown assay, western blotting","journal":"Theranostics","confidence":"Medium","confidence_rationale":"Tier 1-2 — in vitro GEF assay plus pulldown identification, single study","pmids":["40365293"],"is_preprint":false},{"year":2025,"finding":"IRBIT and LIMA1 form a complex with SLC26A3 (DRA) that is required for acute cAMP/Ca2+-stimulated activation of DRA, but not for basal DRA activity. IRBIT is indispensable for maximum ATP-stimulated (but not forskolin-only) DRA activation and for the cAMP/ATP-induced elevation of intracellular Ca2+. cAMP/ATP stimulation increases co-precipitation of LIMA1 with both IRBIT and DRA and increases brush-border DRA and IRBIT abundance.","method":"Co-immunoprecipitation, siRNA knockdown, intracellular pH measurements (DRA activity), surface protein analysis, Ca2+ measurements","journal":"American journal of physiology. Cell physiology","confidence":"Medium","confidence_rationale":"Tier 2-3 — Co-IP, KD, and functional assays in a single study","pmids":["40569378"],"is_preprint":false},{"year":2026,"finding":"Phosphorylation of IRBIT at S80, S84, and S85 provides the primary binding sites for the IP3-binding core (IBC) of IP3R. S68 is the predominant phosphorylation site on IRBIT but is not required for IP3R binding. PKA phosphorylates S62/S64/S66 and CK2 phosphorylates S80/T82/S84/S85 of IRBIT. The phosphorylated S80/S84/S85 peptide computationally binds IBC similarly to IP3, and IRBIT-S68A/S80D/S84D/S85D was sufficient to suppress IP3R-mediated Ca2+ release in living cells.","method":"In vitro kinase assays, pulldown assays, Ca2+ imaging, site-directed mutagenesis, computational modeling","journal":"Communications biology","confidence":"High","confidence_rationale":"Tier 1-2 — in vitro kinase assays plus mutagenesis plus functional Ca2+ imaging, multiple orthogonal methods","pmids":["42032162"],"is_preprint":false}],"current_model":"AHCYL1/IRBIT is a multifunctional scaffold protein that, when phosphorylated at multiple serine residues (particularly S71/S74/S77 and S80/S84/S85 in its PEST domain), acts as a pseudoligand/competitive inhibitor of the IP3 receptor by occupying its IP3-binding core; upon IP3-mediated release or dephosphorylation by PP1, IRBIT translocates to activate diverse ion transporters (NBCe1-B/pNBC1, NHE3, CFTR, Slc26a6, AE2, NBCn1, DRA) by displacing their autoinhibitory domains and recruiting kinase/phosphatase complexes (PP1, SPAK, CaMKII, calcineurin) to fine-tune their phosphorylation and surface expression; beyond ion transport, IRBIT inhibits ribonucleotide reductase (RNR) in a dATP-dependent, phosphorylation-regulated manner to control dNTP pools, inhibits poly(A) polymerase and mRNA polyadenylation via interaction with CPSF/Fip1, suppresses CaMKIIα activity to regulate catecholamine homeostasis, acts as a SAH sensor to inhibit autophagy via PIK3C3, and modulates apoptosis by interacting with Bcl2l10 at mitochondria-associated membranes to promote ER-mitochondria Ca2+ transfer."},"narrative":{"teleology":[{"year":2003,"claim":"The discovery of IRBIT as an IP3R1-binding protein whose interaction requires phosphorylation established AHCYL1 as a regulated component of IP3 receptor signaling, answering how IP3R activity might be modulated by endogenous protein ligands.","evidence":"Affinity purification, co-immunoprecipitation, and alkaline phosphatase treatment in vitro","pmids":["12525476"],"confidence":"High","gaps":["Specific phosphorylation sites not yet mapped","Functional consequence of IRBIT binding on IP3R channel activity not demonstrated","Identity of kinase(s) unknown"]},{"year":2006,"claim":"Establishing that IRBIT competes with IP3 for 10 of 12 shared binding residues on IP3R, and that multiserine phosphorylation of IRBIT is essential, defined IRBIT as a bona fide pseudoligand/competitive inhibitor of IP3R and simultaneously revealed its first non-IP3R target, the pancreatic sodium bicarbonate cotransporter pNBC1.","evidence":"[3H]IP3 binding competition, Ca2+ imaging, mutagenesis for IP3R interaction; co-IP and two-electrode voltage clamp in Xenopus oocytes for pNBC1 activation","pmids":["16793548","16527252","16769890"],"confidence":"High","gaps":["Mechanism by which IRBIT activates pNBC1 unknown","In vivo significance of dual IP3R/pNBC1 regulation not tested","Phosphorylation site hierarchy unresolved"]},{"year":2007,"claim":"Identification of PP1 as a direct IRBIT-binding phosphatase that dephosphorylates S68—a gatekeeper for subsequent S71/S74 phosphorylation—established the phosphorylation cascade controlling IRBIT's affinity for IP3R and introduced IRBIT as a PP1 substrate specifier.","evidence":"In vitro phosphatase assays, mass spectrometry, site-directed mutagenesis, co-immunoprecipitation","pmids":["17635105"],"confidence":"High","gaps":["Kinase responsible for S71/S74 phosphorylation not identified","In vivo dynamics of phosphorylation cycle unknown"]},{"year":2008,"claim":"Demonstrating that IRBIT coordinates pancreatic duct secretion by simultaneously activating basolateral pNBC1 and luminal CFTR through distinct domains, and separately activates NHE3 via CaMKII-dependent trafficking, established IRBIT as a master regulator of epithelial ion transport.","evidence":"siRNA knockdown, ion-selective microelectrodes, single-channel recordings, domain constructs for CFTR/pNBC1; co-IP and surface biotinylation for NHE3","pmids":["19033647","18829453"],"confidence":"High","gaps":["Structural basis for distinct domain requirements for CFTR vs. pNBC1 unknown","Whether IRBIT-NHE3 regulation operates in vivo not tested"]},{"year":2009,"claim":"Discovery that IRBIT binds CPSF/Fip1 and inhibits poly(A) polymerase in a phosphorylation-dependent manner revealed an unexpected role outside ion transport, linking IRBIT to mRNA 3′-end processing and broadening its functional repertoire.","evidence":"Co-immunoprecipitation, RNA pulldown, in vitro PAP activity assay, immunofluorescence","pmids":["19224921"],"confidence":"High","gaps":["Target mRNAs regulated by IRBIT-mediated polyadenylation control not identified","Physiological relevance of IRBIT-PAP inhibition in vivo not demonstrated"]},{"year":2011,"claim":"Elucidation that IRBIT activates NBCe1-B by releasing an autoinhibitory domain, and that IRBIT antagonizes WNK/SPAK kinase signaling by recruiting PP1 to dephosphorylate CFTR and NBCe1-B for surface expression, established the molecular mechanism by which IRBIT orchestrates epithelial secretion through phosphatase/kinase balance.","evidence":"Two-electrode voltage clamp with deletion mutagenesis; siRNA epistasis, phosphoprotein analysis, co-IP for SPAK/PP1 pathway","pmids":["22012331","21317537"],"confidence":"High","gaps":["Structural details of IRBIT-AID interaction unknown","Whether IRBIT-PP1 axis operates in all IRBIT-regulated transporters untested"]},{"year":2013,"claim":"Identification of a conserved positively charged regulatory module shared across NBCe1-B, NBCn1-A, CFTR, and Slc26a6 as the common IRBIT-binding motif, together with in vivo demonstration that IRBIT mediates Ca2+/cAMP synergy in pancreatic secretion using knockout mice, unified the mechanism of IRBIT-dependent transporter activation and validated it physiologically.","evidence":"Systematic mutagenesis and electrophysiology across multiple transporters; Irbit−/− and Slc26a6−/− mouse models with functional secretion assays","pmids":["23431199","23542070"],"confidence":"High","gaps":["Whether the conserved module is sufficient for IRBIT regulation in all family members not fully tested","Tissue-specific phenotypes of Irbit−/− mice beyond pancreas/salivary gland not characterized"]},{"year":2014,"claim":"Discovery that IRBIT forms a dATP-dependent complex with ribonucleotide reductase to inhibit RNR activity and control dNTP pools revealed a fundamental role in nucleotide metabolism and cell cycle progression, far beyond calcium signaling.","evidence":"Co-IP, in vitro RNR activity assays, dNTP pool quantification, cell cycle analysis in IRBIT-depleted HeLa cells","pmids":["25237103"],"confidence":"High","gaps":["Structural basis of dATP-dependent IRBIT-RNR complex unknown","Whether RNR regulation is conserved across all IRBIT-expressing tissues untested"]},{"year":2015,"claim":"Showing that IRBIT suppresses CaMKIIα kinase activity by blocking calmodulin binding, with IRBIT-deficient mice exhibiting elevated catecholamine levels and behavioral abnormalities, established IRBIT as a neuronal signaling modulator controlling dopaminergic function.","evidence":"Co-IP, kinase activity assays, IRBIT-deficient mouse behavioral analysis, TH phosphorylation measurements","pmids":["25922519"],"confidence":"High","gaps":["Whether CaMKIIα inhibition operates in non-neuronal tissues unclear","Contribution of CaMKIIα inhibition vs. IP3R regulation to behavioral phenotype not dissected"]},{"year":2016,"claim":"Demonstration that IRBIT and Bcl2l10 cooperate at mitochondria-associated membranes to regulate IP3R and that apoptotic stress-induced dephosphorylation converts IRBIT from a Bcl2l10 cooperator to an inhibitor, promoting ER-mitochondria Ca2+ transfer and apoptosis, linked IRBIT to programmed cell death.","evidence":"MAM fractionation, co-IP, Ca2+ release and apoptosis assays, dephosphorylation studies","pmids":["27995898"],"confidence":"High","gaps":["In vivo relevance of IRBIT-Bcl2l10 axis in apoptosis not validated in animal models","Identity of phosphatase responsible for apoptotic dephosphorylation of IRBIT unknown"]},{"year":2018,"claim":"Detailed phosphoproteomic dissection of how IRBIT recruits PP1, SPAK, calcineurin, and CaMKII to control distinct phosphorylation sites on NBCe1-B that govern chloride sensitivity and active conformation revealed IRBIT as a multi-kinase/phosphatase scaffolding hub for transporter fine-tuning.","evidence":"Phosphoproteomics, systematic mutagenesis, electrophysiology, co-IP","pmids":["30377224"],"confidence":"High","gaps":["Whether the same multi-kinase scaffold operates on other IRBIT-regulated transporters not shown","Structural basis of simultaneous scaffolding unknown"]},{"year":2020,"claim":"Establishing that the IRBIT-RNR circuit controls intestinal stem cell differentiation in Drosophila, and that IRBIT activates NBCe1-B by competitively displacing the AID from the transmembrane domain via electrostatic interaction, refined both the developmental and biophysical understanding of IRBIT function.","evidence":"Drosophila genetic loss-of-function for RNR regulation; systematic charge-swap mutagenesis and electrophysiology in Xenopus oocytes for AID displacement mechanism","pmids":["32179478","33237573"],"confidence":"High","gaps":["Mammalian stem cell relevance of IRBIT-RNR axis not tested","Whether AID displacement mechanism generalizes to other autoinhibited transporters unknown"]},{"year":2021,"claim":"Discovery that AHCYL1 senses S-adenosyl-L-homocysteine via its C-terminus to inhibit PIK3C3 and suppress autophagy independently of MTORC1 revealed IRBIT as a metabolite sensor linking one-carbon metabolism to autophagy.","evidence":"SAH binding assays, PIK3C3 activity assays, autophagy assays, in vivo validation","pmids":["33993848"],"confidence":"High","gaps":["Whether SAH-sensing and IP3R regulation are coordinated or independent is unknown","Structural basis of SAH binding to C-terminus not resolved"]},{"year":2025,"claim":"Identification of NAD redox state as a modulator of IRBIT-dependent NBCe1-B activation, PREX2/RAC1 GEF activity enhancement by AHCYL1, and the IRBIT/LIMA1/DRA complex for stimulus-dependent Cl−/HCO3− exchange further expanded the scope of IRBIT as a context-dependent signaling integrator.","evidence":"Electrophysiology with NAD+/NADH modulation; LC-MS/MS pulldown with in vitro GEF assay; co-IP with siRNA knockdown and DRA activity measurements","pmids":["39985648","40365293","40569378"],"confidence":"Medium","gaps":["Physiological contexts where NAD redox state controls IRBIT function not defined","PREX2 interaction validated only in NSCLC, generalizability unknown","LIMA1-IRBIT-DRA complex structure and stoichiometry unresolved"]},{"year":2026,"claim":"Definitive mapping of CK2-phosphorylated S80/S84/S85 as the primary IP3R-binding determinants of IRBIT, with computational modeling showing these residues mimic IP3 in the binding core, resolved a long-standing question about which phosphosites are directly responsible for pseudoligand function.","evidence":"In vitro kinase assays (PKA, CK2), pulldown with phosphomimetic mutants, Ca2+ imaging in living cells, computational docking","pmids":["42032162"],"confidence":"High","gaps":["Experimental high-resolution structure of IRBIT-IP3R complex not yet obtained","How CK2 and PKA phosphorylation are coordinated in vivo remains unclear"]},{"year":null,"claim":"Key open questions include the structural basis of IRBIT's simultaneous scaffolding of multiple kinases/phosphatases, how IRBIT partitions among its many targets (IP3R, transporters, RNR, PAP, PIK3C3) in different cell types, and whether IRBIT loss-of-function causes a defined human Mendelian disorder.","evidence":"","pmids":[],"confidence":"Low","gaps":["No high-resolution structure of any IRBIT complex","Target prioritization mechanism across diverse binding partners unknown","No human genetic disease linked to AHCYL1 mutations identified in the literature"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[0,1,2,5,11,15,16,25,30]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[5,6,11,14,21,31]}],"localization":[{"term_id":"GO:0005783","term_label":"endoplasmic reticulum","supporting_discovery_ids":[18,26]},{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[6,13,14,24]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[7,15]},{"term_id":"GO:0005739","term_label":"mitochondrion","supporting_discovery_ids":[18]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[0,1,2,4,9,13,16,32]},{"term_id":"R-HSA-382551","term_label":"Transport of small molecules","supporting_discovery_ids":[3,5,6,10,11,14,21,22,31]},{"term_id":"R-HSA-9612973","term_label":"Autophagy","supporting_discovery_ids":[25]},{"term_id":"R-HSA-5357801","term_label":"Programmed Cell Death","supporting_discovery_ids":[18]},{"term_id":"R-HSA-1430728","term_label":"Metabolism","supporting_discovery_ids":[15,23]}],"complexes":["IRBIT-IP3R complex","IRBIT-RNR complex","IRBIT-CPSF/Fip1 complex"],"partners":["ITPR1","SLC4A4","CFTR","SLC9A3","RRM1","BCL2L10","PIK3C3","PPP1CA"],"other_free_text":[]},"mechanistic_narrative":"AHCYL1 (IRBIT) is a phosphorylation-regulated multifunctional scaffold that integrates calcium signaling, ion transport, nucleotide metabolism, mRNA processing, and autophagy. When phosphorylated at S80/S84/S85 by CK2, IRBIT acts as a pseudoligand that competitively occupies the IP3-binding core of IP3 receptors, suppressing IP3-induced Ca2+ release; IP3 binding or PP1-mediated dephosphorylation releases IRBIT from IP3Rs, enabling it to translocate and activate a broad array of epithelial ion transporters—including NBCe1-B, CFTR, NHE3, Slc26a6, NBCn1, and DRA—by displacing their autoinhibitory domains and recruiting kinase/phosphatase complexes (PP1, SPAK, CaMKII, calcineurin) that control transporter phosphorylation and surface expression [PMID:16793548, PMID:22012331, PMID:21317537, PMID:30377224, PMID:40569378]. Beyond ion transport, IRBIT inhibits ribonucleotide reductase in a dATP- and phosphorylation-dependent manner to regulate dNTP pools and cell cycle progression, suppresses poly(A) polymerase activity through interaction with CPSF/Fip1 to regulate mRNA polyadenylation, inhibits CaMKIIα to control catecholamine homeostasis, senses S-adenosyl-L-homocysteine to inhibit PIK3C3-dependent autophagy, and modulates apoptosis by interacting with Bcl2l10 at mitochondria-associated membranes to promote ER-to-mitochondria Ca2+ transfer [PMID:25237103, PMID:19224921, PMID:25922519, PMID:33993848, PMID:27995898]."},"prefetch_data":{"uniprot":{"accession":"O43865","full_name":"S-adenosylhomocysteine hydrolase-like protein 1","aliases":["DC-expressed AHCY-like molecule","IP(3)Rs binding protein released with IP(3)","IRBIT","Putative adenosylhomocysteinase 2","S-adenosyl-L-homocysteine hydrolase 2","AdoHcyase 2"],"length_aa":530,"mass_kda":59.0,"function":"Multifaceted cellular regulator which coordinates several essential cellular functions including regulation of epithelial HCO3(-) and fluid secretion, mRNA processing and DNA replication. Regulates ITPR1 sensitivity to inositol 1,4,5-trisphosphate, competing for the common binding site and acting as endogenous 'pseudoligand' whose inhibitory activity can be modulated by its phosphorylation status. Promotes the formation of contact points between the endoplasmic reticulum (ER) and mitochondria, facilitating transfer of Ca(2+) from the ER to mitochondria (PubMed:27995898). Under normal cellular conditions, functions cooperatively with BCL2L10 to limit ITPR1-mediated Ca(2+) release but, under apoptotic stress conditions, dephosphorylated which promotes dissociation of both AHCYL1 and BCL2L10 from mitochondria-associated endoplasmic reticulum membranes, inhibits BCL2L10 interaction with ITPR1 and leads to increased Ca(2+) transfer to mitochondria which promotes apoptosis (PubMed:27995898). In the pancreatic and salivary ducts, at resting state, attenuates inositol 1,4,5-trisphosphate-induced calcium release by interacting with ITPR1 (PubMed:16793548). When extracellular stimuli induce ITPR1 phosphorylation or inositol 1,4,5-trisphosphate production, dissociates from ITPR1 to interact with CFTR and SLC26A6, mediating their synergistic activation by calcium and cAMP that stimulates the epithelial secretion of electrolytes and fluid (By similarity). Also activates basolateral SLC4A4 isoform 1 to coordinate fluid and HCO3(-) secretion (PubMed:16769890). Inhibits the effect of STK39 on SLC4A4 and CFTR by recruiting PP1 phosphatase which activates SLC4A4, SLC26A6 and CFTR through dephosphorylation (By similarity). Mediates the induction of SLC9A3 surface expression produced by Angiotensin-2 (PubMed:20584908). Depending on the cell type, activates SLC9A3 in response to calcium or reverses SLC9A3R2-dependent calcium inhibition (PubMed:18829453). May modulate the polyadenylation state of specific mRNAs, both by controlling the subcellular location of FIP1L1 and by inhibiting PAPOLA activity, in response to a stimulus that alters its phosphorylation state (PubMed:19224921). Acts as a (dATP)-dependent inhibitor of ribonucleotide reductase large subunit RRM1, controlling the endogenous dNTP pool and ensuring normal cell cycle progression (PubMed:25237103). In vitro does not exhibit any S-adenosyl-L-homocysteine hydrolase activity (By similarity)","subcellular_location":"Endoplasmic reticulum; Cytoplasm, cytosol; Apical cell membrane; Microsome","url":"https://www.uniprot.org/uniprotkb/O43865/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/AHCYL1","classification":"Not Classified","n_dependent_lines":447,"n_total_lines":1208,"dependency_fraction":0.37003311258278143},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"PIP4K2A","stoichiometry":10.0},{"gene":"AGAP3","stoichiometry":0.2},{"gene":"CANX","stoichiometry":0.2},{"gene":"MIF","stoichiometry":0.2},{"gene":"PIP5K2B","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/AHCYL1","total_profiled":1310},"omim":[{"mim_id":"616520","title":"ADENOSYLHOMOCYSTEINASE-LIKE 2; AHCYL2","url":"https://www.omim.org/entry/616520"},{"mim_id":"607826","title":"ADENOSYLHOMOCYSTEINASE-LIKE 1; AHCYL1","url":"https://www.omim.org/entry/607826"},{"mim_id":"603345","title":"SOLUTE CARRIER FAMILY 4 (SODIUM BICARBONATE COTRANSPORTER), MEMBER 4; SLC4A4","url":"https://www.omim.org/entry/603345"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Cytosol","reliability":"Supported"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/AHCYL1"},"hgnc":{"alias_symbol":["XPVKONA","IRBIT","PPP1R78"],"prev_symbol":[]},"alphafold":{"accession":"O43865","domains":[{"cath_id":"3.40.50.1480","chopping":"91-283_450-505","consensus_level":"medium","plddt":95.2241,"start":91,"end":505},{"cath_id":"3.40.50.720","chopping":"290-446","consensus_level":"medium","plddt":95.7598,"start":290,"end":446}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/O43865","model_url":"https://alphafold.ebi.ac.uk/files/AF-O43865-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-O43865-F1-predicted_aligned_error_v6.png","plddt_mean":85.25},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=AHCYL1","jax_strain_url":"https://www.jax.org/strain/search?query=AHCYL1"},"sequence":{"accession":"O43865","fasta_url":"https://rest.uniprot.org/uniprotkb/O43865.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/O43865/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/O43865"}},"corpus_meta":[{"pmid":"12525476","id":"PMC_12525476","title":"IRBIT, 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interacting with the Bcl-2 homolog, Bcl2l10, and by promoting ER-mitochondria contact.","date":"2016","source":"eLife","url":"https://pubmed.ncbi.nlm.nih.gov/27995898","citation_count":62,"is_preprint":false},{"pmid":"18829453","id":"PMC_18829453","title":"IRBIT, inositol 1,4,5-triphosphate (IP3) receptor-binding protein released with IP3, binds Na+/H+ exchanger NHE3 and activates NHE3 activity in response to calcium.","date":"2008","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/18829453","citation_count":62,"is_preprint":false},{"pmid":"22012331","id":"PMC_22012331","title":"Relief of autoinhibition of the electrogenic Na-HCO(3) [corrected] cotransporter NBCe1-B: role of IRBIT vs.amino-terminal truncation.","date":"2011","source":"American journal of physiology. 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IRBIT is a novel regulator of ribonucleotide reductase in higher eukaryotes.","date":"2014","source":"Science (New York, N.Y.)","url":"https://pubmed.ncbi.nlm.nih.gov/25237103","citation_count":44,"is_preprint":false},{"pmid":"24518248","id":"PMC_24518248","title":"IRBIT: a regulator of ion channels and ion transporters.","date":"2014","source":"Biochimica et biophysica acta","url":"https://pubmed.ncbi.nlm.nih.gov/24518248","citation_count":39,"is_preprint":false},{"pmid":"25922519","id":"PMC_25922519","title":"IRBIT regulates CaMKIIα activity and contributes to catecholamine homeostasis through tyrosine hydroxylase phosphorylation.","date":"2015","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/25922519","citation_count":38,"is_preprint":false},{"pmid":"16527252","id":"PMC_16527252","title":"Binding of IRBIT to the IP3 receptor: determinants and functional effects.","date":"2006","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/16527252","citation_count":37,"is_preprint":false},{"pmid":"18536033","id":"PMC_18536033","title":"The IRBIT domain adds new functions to the AHCY family.","date":"2008","source":"BioEssays : news and reviews in molecular, cellular and developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/18536033","citation_count":36,"is_preprint":false},{"pmid":"23026752","id":"PMC_23026752","title":"The WNK/SPAK and IRBIT/PP1 pathways in epithelial fluid and electrolyte transport.","date":"2012","source":"Physiology (Bethesda, Md.)","url":"https://pubmed.ncbi.nlm.nih.gov/23026752","citation_count":31,"is_preprint":false},{"pmid":"27062503","id":"PMC_27062503","title":"Mutations in the IRBIT domain of ITPR1 are a frequent cause of autosomal dominant nonprogressive congenital ataxia.","date":"2016","source":"Clinical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/27062503","citation_count":31,"is_preprint":false},{"pmid":"19224921","id":"PMC_19224921","title":"Inositol 1,4,5-triphosphate receptor-binding protein released with inositol 1,4,5-triphosphate (IRBIT) associates with components of the mRNA 3' processing machinery in a phosphorylation-dependent manner and inhibits polyadenylation.","date":"2009","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/19224921","citation_count":31,"is_preprint":false},{"pmid":"23145124","id":"PMC_23145124","title":"AHCYL1 is mediated by estrogen-induced ERK1/2 MAPK cell signaling and microRNA regulation to effect functional aspects of the avian oviduct.","date":"2012","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/23145124","citation_count":28,"is_preprint":false},{"pmid":"33993848","id":"PMC_33993848","title":"AHCYL1 senses SAH to inhibit autophagy through interaction with PIK3C3 in an MTORC1-independent manner.","date":"2021","source":"Autophagy","url":"https://pubmed.ncbi.nlm.nih.gov/33993848","citation_count":27,"is_preprint":false},{"pmid":"16754674","id":"PMC_16754674","title":"Suppression and overexpression of adenosylhomocysteine hydrolase-like protein 1 (AHCYL1) influences zebrafish embryo development: a possible role for AHCYL1 in inositol phospholipid signaling.","date":"2006","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/16754674","citation_count":27,"is_preprint":false},{"pmid":"22929228","id":"PMC_22929228","title":"ROCK-phosphorylated vimentin modifies mutant huntingtin aggregation via sequestration of IRBIT.","date":"2012","source":"Molecular neurodegeneration","url":"https://pubmed.ncbi.nlm.nih.gov/22929228","citation_count":24,"is_preprint":false},{"pmid":"19220705","id":"PMC_19220705","title":"An IRBIT homologue lacks binding activity to inositol 1,4,5-trisphosphate receptor due to the unique N-terminal appendage.","date":"2009","source":"Journal of neurochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/19220705","citation_count":22,"is_preprint":false},{"pmid":"21152975","id":"PMC_21152975","title":"IRBIT: it is everywhere.","date":"2010","source":"Neurochemical research","url":"https://pubmed.ncbi.nlm.nih.gov/21152975","citation_count":22,"is_preprint":false},{"pmid":"22826361","id":"PMC_22826361","title":"Paradoxical expression of AHCYL1 affecting ovarian carcinogenesis between chickens and women.","date":"2012","source":"Experimental biology and medicine (Maywood, N.J.)","url":"https://pubmed.ncbi.nlm.nih.gov/22826361","citation_count":21,"is_preprint":false},{"pmid":"27279487","id":"PMC_27279487","title":"The NHERF1 PDZ1 domain and IRBIT interact and mediate the activation of Na+/H+ exchanger 3 by ANG II.","date":"2016","source":"American journal of physiology. 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reports","url":"https://pubmed.ncbi.nlm.nih.gov/33727633","citation_count":7,"is_preprint":false},{"pmid":"31366495","id":"PMC_31366495","title":"Low IRBIT Levels Are Associated With Chemo-resistance in Gastric Cancer Patients.","date":"2019","source":"Anticancer research","url":"https://pubmed.ncbi.nlm.nih.gov/31366495","citation_count":6,"is_preprint":false},{"pmid":"36872327","id":"PMC_36872327","title":"S-adenosylhomocysteine hydrolase-like protein 1 (AHCYL1) inhibits lung cancer tumorigenesis by regulating cell plasticity.","date":"2023","source":"Biology direct","url":"https://pubmed.ncbi.nlm.nih.gov/36872327","citation_count":5,"is_preprint":false},{"pmid":"35351819","id":"PMC_35351819","title":"Synaptic plasticity in hippocampal CA1 neurons of mice lacking inositol-1,4,5-trisphosphate receptor-binding protein released with IP3 (IRBIT).","date":"2022","source":"Learning & memory (Cold Spring Harbor, N.Y.)","url":"https://pubmed.ncbi.nlm.nih.gov/35351819","citation_count":5,"is_preprint":false},{"pmid":"22453947","id":"PMC_22453947","title":"The discovery and structural investigation of the IP₃ receptor and the associated IRBIT protein.","date":"2012","source":"Advances in experimental medicine and biology","url":"https://pubmed.ncbi.nlm.nih.gov/22453947","citation_count":5,"is_preprint":false},{"pmid":"37082243","id":"PMC_37082243","title":"Dietary sodium enhances the expression of SLC4 family transporters, IRBIT, L-IRBIT, and PP1 in rat kidney: Insights into the molecular mechanism for renal sodium handling.","date":"2023","source":"Frontiers in physiology","url":"https://pubmed.ncbi.nlm.nih.gov/37082243","citation_count":4,"is_preprint":false},{"pmid":"39929439","id":"PMC_39929439","title":"Cardiac hypertrophy induced by overexpression of IP3-released inositol 1, 4, 5-trisphosphate receptor-binding protein (IRBIT).","date":"2025","source":"Journal of molecular and cellular cardiology","url":"https://pubmed.ncbi.nlm.nih.gov/39929439","citation_count":3,"is_preprint":false},{"pmid":"39985648","id":"PMC_39985648","title":"Redox state of NAD modulates the activation of Na-bicarbonate cotransporter NBCe1-B via IRBIT and L-IRBIT.","date":"2025","source":"Science China. Life sciences","url":"https://pubmed.ncbi.nlm.nih.gov/39985648","citation_count":3,"is_preprint":false},{"pmid":"34923880","id":"PMC_34923880","title":"Genetic variants in SCNN1B and AHCYL1 are associated with eggshell quality in Chinese domestic laying ducks (Anas platyrhynchos).","date":"2022","source":"British poultry science","url":"https://pubmed.ncbi.nlm.nih.gov/34923880","citation_count":2,"is_preprint":false},{"pmid":"40365293","id":"PMC_40365293","title":"AHCYL1 mediates the tumor-promoting effect of PREX2 in non-small cell lung carcinoma.","date":"2025","source":"Theranostics","url":"https://pubmed.ncbi.nlm.nih.gov/40365293","citation_count":0,"is_preprint":false},{"pmid":"40569378","id":"PMC_40569378","title":"IRBIT and LIMA1 associate with and are necessary for epithelial cell SLC26A3 (DRA) stimulation by cAMP/ATP.","date":"2025","source":"American journal of physiology. Cell physiology","url":"https://pubmed.ncbi.nlm.nih.gov/40569378","citation_count":0,"is_preprint":false},{"pmid":"42032162","id":"PMC_42032162","title":"Deciphering the multi-site phos-code of IRBIT underlying its binding to IP3R.","date":"2026","source":"Communications biology","url":"https://pubmed.ncbi.nlm.nih.gov/42032162","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2025.08.15.670264","title":"Deployment of non-canonical splicing in tunicate genomes is mediated by divergent U2AF function and re-patterning of snRNA m6A modification","date":"2025-08-17","source":"bioRxiv","url":"https://doi.org/10.1101/2025.08.15.670264","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":30202,"output_tokens":8393,"usd":0.10825},"stage2":{"model":"claude-opus-4-6","input_tokens":12156,"output_tokens":4377,"usd":0.255308},"total_usd":0.363558,"stage1_batch_id":"msgbatch_01TqNM6p6FsoMBT2jzQTwKBr","stage2_batch_id":"msgbatch_01Ya473eco8sTHbvRymQaU8o","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2003,\n      \"finding\": \"IRBIT (AHCYL1) was identified as a novel IP3 receptor type 1 (IP3R1)-binding protein that is released from IP3R1 upon IP3 binding. The N-terminal region of IRBIT is essential for the interaction, and the IRBIT binding region on IP3R1 was mapped to the IP3 binding core. Alkaline phosphatase treatment abolished the interaction, indicating that phosphorylation of IRBIT is required for binding.\",\n      \"method\": \"Affinity purification, in vitro binding assays, co-immunoprecipitation, alkaline phosphatase treatment\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — multiple orthogonal methods, foundational discovery paper with high citation count\",\n      \"pmids\": [\"12525476\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"IRBIT competes with IP3 for the common binding site on IP3R, suppressing IP3R activation. Multiserine phosphorylation of IRBIT is essential for binding to IP3R, and 10 of 12 key amino acids in IP3R for IP3 recognition also participate in IRBIT binding, establishing IRBIT as an endogenous pseudoligand of IP3R.\",\n      \"method\": \"[3H]IP3 binding assays, in vitro Ca2+ release assays, Ca2+ imaging in intact cells, mutagenesis\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — reconstitution assays plus mutagenesis plus cell imaging, high citation count\",\n      \"pmids\": [\"16793548\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"IRBIT directly interacts with IP3R, requiring both the suppressor domain and the IP3-binding core of IP3R for strong interaction. A PEST motif and PDZ-ligand on IRBIT are critical for IP3R interaction, and Asp-73 is a critical residue. IRBIT inhibits both IP3 binding and IP3-induced Ca2+ release.\",\n      \"method\": \"Direct binding assays, deletion and point mutagenesis, IP3 binding competition, Ca2+ release assays\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — direct binding with mutagenesis, consistent with independent reports\",\n      \"pmids\": [\"16527252\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"IRBIT specifically binds to the pancreas-type NBC1 (pNBC1) but not kidney-type NBC1 (kNBC1), through the N-terminal pNBC1-specific domain. IRBIT binding depends on phosphorylation of multiple serine residues of IRBIT. Co-expression of IRBIT in Xenopus oocytes is required for pNBC1 to manifest substantial electrogenic activity, revealing IRBIT as an activator of pNBC1.\",\n      \"method\": \"Co-immunoprecipitation, two-electrode voltage clamp in Xenopus oocytes, mutagenesis\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — electrophysiology plus binding assays, high citation count, replicated by subsequent studies\",\n      \"pmids\": [\"16769890\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Protein phosphatase-1 (PP1) binds to a conserved PP1-binding site on IRBIT (preceding the PEST domain), dephosphorylates Ser68 of IRBIT, and thereby reduces IRBIT's affinity for IP3R. Phosphorylation of Ser68 is required for subsequent phosphorylation of Ser71 and Ser74, and Ser71/Ser74 phosphorylation is sufficient to enable IRBIT-mediated inhibition of IP3 binding. IRBIT thus acts as a substrate specifier for PP1.\",\n      \"method\": \"In vitro binding assays, mass spectrometry, site-directed mutagenesis, phosphatase assays, Co-IP\",\n      \"journal\": \"The Biochemical journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — multiple orthogonal methods including in vitro kinase/phosphatase assays and mutagenesis\",\n      \"pmids\": [\"17635105\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"IRBIT activates both basolateral pNBC1 and luminal CFTR in pancreatic duct to coordinate fluid and HCO3- secretion. siRNA knockdown of IRBIT markedly inhibited ductal pNBC1 and CFTR activities, luminal Cl- absorption, HCO3- secretion, and fluid secretion. IRBIT activates pNBC1 via the PEST domain alone, while activation of CFTR requires multiple IRBIT domains, indicating distinct mechanisms.\",\n      \"method\": \"siRNA knockdown, video microscopy, ion-selective microelectrodes, single-channel recordings, expression of IRBIT domain constructs in HEK cells\",\n      \"journal\": \"The Journal of clinical investigation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple physiological assays plus domain dissection, high citation count\",\n      \"pmids\": [\"19033647\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"IRBIT binds to the C-terminal domain of NHE3 and activates NHE3 activity in a Ca2+-dependent manner. IRBIT-dependent activation of NHE3 involves exocytic trafficking of NHE3 to the plasma membrane, requires calmodulin and CaMKII, and can reverse NHERF2-dependent inhibition of NHE3.\",\n      \"method\": \"Co-immunoprecipitation, ectopic expression, siRNA knockdown, NHE3 activity assays, cell surface biotinylation, pharmacological inhibition\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple complementary methods establishing binding, trafficking and functional outcome\",\n      \"pmids\": [\"18829453\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"IRBIT interacts with CPSF (cleavage and polyadenylation specificity factor), with the primary target being Fip1 subunit, in a phosphorylation-dependent manner. IRBIT is recruited to polyadenylation signal-containing RNA. Phosphorylation of IRBIT's serine-rich region promotes cytoplasmic redistribution of Fip1. IRBIT also binds poly(A) polymerase (PAP) and inhibits PAP activity in a phosphorylation-dependent manner.\",\n      \"method\": \"Co-immunoprecipitation, in vitro binding assays, RNA pulldown, PAP activity assay, immunofluorescence\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — in vitro enzymatic assay plus multiple binding and localization methods\",\n      \"pmids\": [\"19224921\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Long-IRBIT (AHCYL2), an IRBIT homologue, heteromerizes with IRBIT but retains little ability to interact with IP3R despite conserving critical amino acids. The unique N-terminal appendage (LISN domain) of Long-IRBIT inhibits its interaction with IP3R. Long-IRBIT and IRBIT show distinct distributions in mouse cerebellar cortex.\",\n      \"method\": \"Co-immunoprecipitation, deletion mutagenesis, immunohistochemistry\",\n      \"journal\": \"Journal of neurochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — Co-IP and mutagenesis in a single study\",\n      \"pmids\": [\"19220705\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"IRBIT mediates angiotensin II (ANG II)-induced activation of NHE3 via CaMKII-dependent phosphorylation. ANG II transiently increases IRBIT binding to NHE3, and inhibition of CaMKII blocks both ANG II-induced IRBIT-NHE3 binding and NHE3 surface abundance. Mutations of Ser-68, Ser-71, and Ser-74 of IRBIT decreased binding to NHE3 and reduced NHE3 activity.\",\n      \"method\": \"siRNA knockdown, overexpression, co-immunoprecipitation, NHE3 activity assays, CaMKII inhibition, site-directed mutagenesis\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods linking IRBIT phosphorylation to NHE3 regulation\",\n      \"pmids\": [\"20584908\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"IRBIT activates NBCe1-B (pNBC1) by relieving autoinhibition. Deletion of the autoinhibitory domain (AID, residues ~1-87) stimulates NBCe1-B to the same extent as coexpression of wild-type IRBIT. An NBCe1-B construct lacking residues 2-16 is fully autoinhibited but cannot be stimulated by IRBIT, indicating IRBIT-binding and autoinhibitory determinants are distinct but overlapping.\",\n      \"method\": \"Two-electrode voltage clamp in Xenopus oocytes, deletion mutagenesis\",\n      \"journal\": \"American journal of physiology. Cell physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — electrophysiology with systematic mutagenesis\",\n      \"pmids\": [\"22012331\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"IRBIT governs epithelial secretion by antagonizing the WNK/SPAK kinase pathway. WNK kinases act as scaffolds to recruit SPAK, which phosphorylates CFTR and NBCe1-B, reducing their cell surface expression. IRBIT opposes this by recruiting PP1 to the complex to dephosphorylate CFTR and NBCe1-B, restoring their surface expression and activity. Silencing of both SPAK and IRBIT rescues the secretion defect caused by IRBIT silencing alone.\",\n      \"method\": \"siRNA knockdown, phosphoprotein analysis, co-immunoprecipitation, epithelial secretion assays, genetic epistasis\",\n      \"journal\": \"The Journal of clinical investigation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — epistasis plus multiple molecular methods across independent labs\",\n      \"pmids\": [\"21317537\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"IRBIT interacts with the Cl-/HCO3- exchanger AE2; IRBIT binding facilitates lysosomal degradation of AE2, while coexisting L-IRBIT inhibits this degradation, resulting in opposing regulation of AE2 expression and activity. This affects regulatory volume increase and cell migration.\",\n      \"method\": \"Co-immunoprecipitation, KO cell lines, AE2 activity assays, lysosome inhibitor (bafilomycin A1), cell migration assays\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — KO cells with multiple assays but single study\",\n      \"pmids\": [\"33727633\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"IRBIT mediates synergy between Ca2+ and cAMP signaling pathways in pancreatic and salivary duct epithelial cells. cAMP-induced phosphorylation of IP3Rs reduces their affinity for Irbit, allowing weak IP3 production to release Irbit from IP3Rs; Irbit then translocates to CFTR and Slc26a6 in the plasma membrane to stimulate secretion. This synergy was absent in Irbit-/- and Slc26a6-/- mice and in mice with IP3Rs mutated at PKA phosphorylation sites.\",\n      \"method\": \"Knockout mouse models, immunoprecipitation, intracellular pH measurements, Cl- current recordings, fluid secretion assays, genetic epistasis\",\n      \"journal\": \"Gastroenterology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple KO models, orthogonal functional assays, genetic epistasis\",\n      \"pmids\": [\"23542070\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"A conserved positively charged module within NBCe1-B (residues 37-65) is required for interaction and activation of NBCe1-B and NBCn1-A by IRBIT and for regulation by PIP2. IRBIT and PIP2 activate these transporters in a nonadditive but complementary manner. Phosphorylation of Ser65 mediates SPAK regulation while Thr49 is required for IRBIT and SPAK regulation. The same regulatory module was identified in CFTR R domain and Slc26a6 STAS domain, and IRBIT binds these domains.\",\n      \"method\": \"Mutagenesis, Co-IP, electrophysiology in Xenopus oocytes\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — mutagenesis plus electrophysiology plus binding assays across multiple transporters\",\n      \"pmids\": [\"23431199\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"IRBIT forms a deoxyadenosine triphosphate (dATP)-dependent complex with ribonucleotide reductase (RNR) in metazoans, stabilizing dATP in the activity site of RNR and inhibiting the enzyme. Formation of the RNR-IRBIT complex is regulated by phosphorylation of IRBIT. Ablation of IRBIT in HeLa cells causes imbalanced dNTP pools and altered cell cycle progression.\",\n      \"method\": \"Co-immunoprecipitation, in vitro RNR activity assays, phosphorylation analysis, dNTP pool measurement, cell cycle analysis in IRBIT-depleted cells\",\n      \"journal\": \"Science (New York, N.Y.)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — biochemical reconstitution with in vitro enzyme assays plus cell-based phenotype\",\n      \"pmids\": [\"25237103\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"IRBIT binds CaMKIIα and suppresses its kinase activity by inhibiting calmodulin binding to CaMKIIα. In IRBIT-deficient mice, TH phosphorylation by CaMKIIα is increased in the ventral tegmental area, leading to elevated catecholamine levels, increased locomotor activity, and social abnormalities.\",\n      \"method\": \"Co-immunoprecipitation, kinase activity assays, IRBIT-deficient mice, behavioral analysis, phosphorylation assays\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — biochemical binding/kinase assays plus in vivo KO phenotype\",\n      \"pmids\": [\"25922519\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"IRBIT interacts with all PIPK isoforms in heterologous systems and specifically with PIPKIα and PIPKIIα in mouse cerebellum. Two conserved catalytic aspartate residues of PIPKIα and PIPKIIα are required for IRBIT binding. Phosphatidylinositol 4-phosphate, Mg2+, and/or ATP interfere with the interaction. Mutations in the serine-rich region of IRBIT affect selectivity for PIPKIα versus PIPKIIα. IRBIT, PIPKIα, and NBCe1-B form a signaling complex.\",\n      \"method\": \"Co-immunoprecipitation, in vitro binding assays, site-directed mutagenesis, immunocytochemistry\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — mutagenesis plus binding assays, single study\",\n      \"pmids\": [\"26509711\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"IRBIT interacts with the Bcl-2 homolog Bcl2l10, and together they exert additive inhibition of IP3R in the physiological state. IRBIT and Bcl2l10 associate in mitochondria-associated membranes (MAMs). Upon apoptotic stress, IRBIT is dephosphorylated and becomes an inhibitor of Bcl2l10; IRBIT also promotes ER-mitochondria contact, facilitating massive Ca2+ transfer to mitochondria and promoting apoptosis.\",\n      \"method\": \"Co-immunoprecipitation, fractionation (MAM isolation), Ca2+ release assays, apoptosis assays, dephosphorylation studies\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods including subcellular fractionation, functional assays, and mechanistic dissection\",\n      \"pmids\": [\"27995898\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"NHERF1 PDZ1 domain interacts with IRBIT and is required for ANG II-mediated forward trafficking and activation of NHE3. IRBIT phosphorylation at Ser68 is necessary for assembly of the NHERF1-IRBIT-NHE3 complex, and IRBIT is indispensable for ANG II-induced increase in NHERF1-NHE3 interaction.\",\n      \"method\": \"Co-immunoprecipitation, overexpression of dominant negative constructs, surface NHE3 quantification, site-directed mutagenesis\",\n      \"journal\": \"American journal of physiology. Renal physiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — multiple binding and functional assays in a single study\",\n      \"pmids\": [\"27279487\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"IRBIT and Long-IRBIT form homo- and heteromultimers. N-terminal splicing of Long-IRBIT changes protein stability and selectivity toward target molecules. Different combinations of IRBIT family multimers contribute to functional diversity.\",\n      \"method\": \"Co-immunoprecipitation, expression analysis in multiple tissues, mutagenesis of N-terminal regions\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — Co-IP and expression profiling, single study\",\n      \"pmids\": [\"28348216\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"IRBIT recruits PP1 and SPAK to control phosphorylation of Ser65 in NBCe1-B, affecting Cl-in sensing by the 32GXXXP36 motif. IRBIT also recruits calcineurin and CaMKII to control phosphorylation of Ser12, affecting Cl-in sensing by 194GXXXP198. Phosphorylation of Ser232, Ser233, and Ser235 determines the active vs. inactive conformation of NBCe1-B, with the pSer233/pSer235 form mimicking IRBIT-activated NBCe1-B but insensitive to Cl-in inhibition.\",\n      \"method\": \"Phosphoproteomic analysis, mutagenesis, electrophysiology, co-immunoprecipitation\",\n      \"journal\": \"Science signaling\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — phosphoproteomics plus systematic mutagenesis and electrophysiology\",\n      \"pmids\": [\"30377224\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"IRBIT activates NBCe1-B by releasing the autoinhibitory domain (AID) from the transmembrane domain. The AID (residues 40-85) acts as a brake binding the transmembrane domain via electrostatic interaction; IRBIT competitively binds the AID to release this brake. The IRBIT-binding domain of NBCe1-B consists of negatively charged (residues 1-24) and positively charged (residues 40-52) arms. Negatively charged Asp/Glu residues plus Ser/Thr residues in IRBIT PEST domain are required for NBCe1-B interaction.\",\n      \"method\": \"Electrophysiology (Xenopus oocytes), systematic mutagenesis, charge manipulation experiments\",\n      \"journal\": \"The Journal of physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — systematic mutagenesis with electrophysiology establishing molecular mechanism\",\n      \"pmids\": [\"33237573\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"IRBIT regulates ribonucleotide reductase (RNR) activity in Drosophila ISC progeny, and IRBIT expression directs differentiation of intestinal stem cell progeny by suppressing RNR activity. Disruption of the IRBIT-RNR circuit causes premature loss of intestinal tissue integrity; age-related dysplasia can be reversed by suppressing RNR in ISC progeny.\",\n      \"method\": \"Genetic loss-of-function in Drosophila, tissue histology, RNR activity assays\",\n      \"journal\": \"iScience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — Drosophila ortholog with genetic and functional validation, consistent with mammalian RNR regulation\",\n      \"pmids\": [\"32179478\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"IRBIT stabilizes NBCn1 transporter expression in the plasma membrane and enhances cancer cell migration. Overexpression of IRBIT enhanced NBCn1 activity and cell migration; knockdown of IRBIT or NBCn1 attenuated cell migration. EGF signaling recruits IRBIT to maintain NBCn1 in the plasma membrane.\",\n      \"method\": \"Overexpression, siRNA knockdown, NBC activity assays, cell migration assays, surface protein analysis\",\n      \"journal\": \"Pharmaceutics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — functional assays in cancer cells, single study\",\n      \"pmids\": [\"32867284\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"AHCYL1 (IRBIT) functions as a SAH (S-adenosyl-L-homocysteine) sensor to inhibit autophagy through PIK3C3. The C-terminus of AHCYL1 specifically binds SAH, and this interaction promotes binding of the N-terminus to the catalytic domain of PIK3C3, inhibiting PIK3C3 activity and thus suppressing autophagy in an MTORC1-independent manner.\",\n      \"method\": \"Co-immunoprecipitation, PIK3C3 activity assays, autophagy assays, SAH binding experiments, in vivo validation\",\n      \"journal\": \"Autophagy\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — enzymatic assay plus binding domain mapping plus in vivo validation\",\n      \"pmids\": [\"33993848\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"IRBIT physically interacts with microtubule-associated protein tau in brain tissues and cultured cells. Tau overexpression modifies the close localization of AHCYL1/IRBIT to IP3R at the endoplasmic reticulum, as shown by proximity ligation assay.\",\n      \"method\": \"Protein microarray, co-immunoprecipitation, proximity ligation assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — Co-IP and proximity ligation, single study, no functional mechanism established\",\n      \"pmids\": [\"35218773\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"IRBIT knockout in INS-1 cells reduces insulin content and glucose-stimulated insulin secretion, reduces INS2 mRNA levels, and increases nuclear localization of AHCY. In RyR2 KO cells, IRBIT protein levels are reduced, suggesting RyR2 maintains IRBIT levels. IRBIT and RyR2 deletion causes increased exon 2 methylation of insulin genes.\",\n      \"method\": \"CRISPR knockout, insulin secretion assays, qPCR, nuclear fractionation, DNA methylation analysis, proteomics\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — KO phenotype with multiple readouts but mechanistic link is partial\",\n      \"pmids\": [\"35562179\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"AHCYL1 deficiency in NRAS-mutant melanoma results in decreased ER calcium levels, activation of the unfolded protein response (UPR), and downstream apoptosis. AHCYL1 transcription in NRAS-mutated melanoma is regulated by ATF2. AHCYL1 is selectively upregulated and required for cell proliferation specifically in NRAS-mutated (not BRAF V600E) melanoma.\",\n      \"method\": \"RNAi screen, AHCYL1 knockdown, Ca2+ measurements, UPR assays, apoptosis assays, xenograft models\",\n      \"journal\": \"Molecular cancer research : MCR\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — functional knockdown with multiple readouts but mechanistic dissection limited\",\n      \"pmids\": [\"38294692\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"IRBIT activates NBCe1-B in a NAD redox state-dependent manner; IRBIT and L-IRBIT serve as NAD cofactors, with NAD+ enhancing and NADH decreasing NBCe1-B activity. Blocking the NAD salvage pathway greatly decreases NBCe1-B activation by the IRBITs, establishing NAD redox state as a modulator of IRBIT-dependent transporter regulation.\",\n      \"method\": \"Electrophysiology, pharmacological inhibition of NAD salvage pathway, NAD+/NADH administration\",\n      \"journal\": \"Science China. Life sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — functional assays with pharmacological tools, single study\",\n      \"pmids\": [\"39985648\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"AHCYL1 enhances PREX2 GEF (guanine nucleotide exchange factor) activity toward RAC1 by alleviating mutual inhibition between PREX2 and PTEN, thereby intensifying tumor-promoting effects of PREX2 in NSCLC. AHCYL1 was identified as a novel PREX2-interacting protein.\",\n      \"method\": \"Pull-down assay, LC-MS/MS, in vitro GEF assay, active RAC1 pulldown assay, western blotting\",\n      \"journal\": \"Theranostics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1-2 — in vitro GEF assay plus pulldown identification, single study\",\n      \"pmids\": [\"40365293\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"IRBIT and LIMA1 form a complex with SLC26A3 (DRA) that is required for acute cAMP/Ca2+-stimulated activation of DRA, but not for basal DRA activity. IRBIT is indispensable for maximum ATP-stimulated (but not forskolin-only) DRA activation and for the cAMP/ATP-induced elevation of intracellular Ca2+. cAMP/ATP stimulation increases co-precipitation of LIMA1 with both IRBIT and DRA and increases brush-border DRA and IRBIT abundance.\",\n      \"method\": \"Co-immunoprecipitation, siRNA knockdown, intracellular pH measurements (DRA activity), surface protein analysis, Ca2+ measurements\",\n      \"journal\": \"American journal of physiology. Cell physiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — Co-IP, KD, and functional assays in a single study\",\n      \"pmids\": [\"40569378\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"Phosphorylation of IRBIT at S80, S84, and S85 provides the primary binding sites for the IP3-binding core (IBC) of IP3R. S68 is the predominant phosphorylation site on IRBIT but is not required for IP3R binding. PKA phosphorylates S62/S64/S66 and CK2 phosphorylates S80/T82/S84/S85 of IRBIT. The phosphorylated S80/S84/S85 peptide computationally binds IBC similarly to IP3, and IRBIT-S68A/S80D/S84D/S85D was sufficient to suppress IP3R-mediated Ca2+ release in living cells.\",\n      \"method\": \"In vitro kinase assays, pulldown assays, Ca2+ imaging, site-directed mutagenesis, computational modeling\",\n      \"journal\": \"Communications biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — in vitro kinase assays plus mutagenesis plus functional Ca2+ imaging, multiple orthogonal methods\",\n      \"pmids\": [\"42032162\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"AHCYL1/IRBIT is a multifunctional scaffold protein that, when phosphorylated at multiple serine residues (particularly S71/S74/S77 and S80/S84/S85 in its PEST domain), acts as a pseudoligand/competitive inhibitor of the IP3 receptor by occupying its IP3-binding core; upon IP3-mediated release or dephosphorylation by PP1, IRBIT translocates to activate diverse ion transporters (NBCe1-B/pNBC1, NHE3, CFTR, Slc26a6, AE2, NBCn1, DRA) by displacing their autoinhibitory domains and recruiting kinase/phosphatase complexes (PP1, SPAK, CaMKII, calcineurin) to fine-tune their phosphorylation and surface expression; beyond ion transport, IRBIT inhibits ribonucleotide reductase (RNR) in a dATP-dependent, phosphorylation-regulated manner to control dNTP pools, inhibits poly(A) polymerase and mRNA polyadenylation via interaction with CPSF/Fip1, suppresses CaMKIIα activity to regulate catecholamine homeostasis, acts as a SAH sensor to inhibit autophagy via PIK3C3, and modulates apoptosis by interacting with Bcl2l10 at mitochondria-associated membranes to promote ER-mitochondria Ca2+ transfer.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"AHCYL1 (IRBIT) is a phosphorylation-regulated multifunctional scaffold that integrates calcium signaling, ion transport, nucleotide metabolism, mRNA processing, and autophagy. When phosphorylated at S80/S84/S85 by CK2, IRBIT acts as a pseudoligand that competitively occupies the IP3-binding core of IP3 receptors, suppressing IP3-induced Ca2+ release; IP3 binding or PP1-mediated dephosphorylation releases IRBIT from IP3Rs, enabling it to translocate and activate a broad array of epithelial ion transporters—including NBCe1-B, CFTR, NHE3, Slc26a6, NBCn1, and DRA—by displacing their autoinhibitory domains and recruiting kinase/phosphatase complexes (PP1, SPAK, CaMKII, calcineurin) that control transporter phosphorylation and surface expression [PMID:16793548, PMID:22012331, PMID:21317537, PMID:30377224, PMID:40569378]. Beyond ion transport, IRBIT inhibits ribonucleotide reductase in a dATP- and phosphorylation-dependent manner to regulate dNTP pools and cell cycle progression, suppresses poly(A) polymerase activity through interaction with CPSF/Fip1 to regulate mRNA polyadenylation, inhibits CaMKIIα to control catecholamine homeostasis, senses S-adenosyl-L-homocysteine to inhibit PIK3C3-dependent autophagy, and modulates apoptosis by interacting with Bcl2l10 at mitochondria-associated membranes to promote ER-to-mitochondria Ca2+ transfer [PMID:25237103, PMID:19224921, PMID:25922519, PMID:33993848, PMID:27995898].\",\n  \"teleology\": [\n    {\n      \"year\": 2003,\n      \"claim\": \"The discovery of IRBIT as an IP3R1-binding protein whose interaction requires phosphorylation established AHCYL1 as a regulated component of IP3 receptor signaling, answering how IP3R activity might be modulated by endogenous protein ligands.\",\n      \"evidence\": \"Affinity purification, co-immunoprecipitation, and alkaline phosphatase treatment in vitro\",\n      \"pmids\": [\"12525476\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Specific phosphorylation sites not yet mapped\", \"Functional consequence of IRBIT binding on IP3R channel activity not demonstrated\", \"Identity of kinase(s) unknown\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Establishing that IRBIT competes with IP3 for 10 of 12 shared binding residues on IP3R, and that multiserine phosphorylation of IRBIT is essential, defined IRBIT as a bona fide pseudoligand/competitive inhibitor of IP3R and simultaneously revealed its first non-IP3R target, the pancreatic sodium bicarbonate cotransporter pNBC1.\",\n      \"evidence\": \"[3H]IP3 binding competition, Ca2+ imaging, mutagenesis for IP3R interaction; co-IP and two-electrode voltage clamp in Xenopus oocytes for pNBC1 activation\",\n      \"pmids\": [\"16793548\", \"16527252\", \"16769890\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism by which IRBIT activates pNBC1 unknown\", \"In vivo significance of dual IP3R/pNBC1 regulation not tested\", \"Phosphorylation site hierarchy unresolved\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Identification of PP1 as a direct IRBIT-binding phosphatase that dephosphorylates S68—a gatekeeper for subsequent S71/S74 phosphorylation—established the phosphorylation cascade controlling IRBIT's affinity for IP3R and introduced IRBIT as a PP1 substrate specifier.\",\n      \"evidence\": \"In vitro phosphatase assays, mass spectrometry, site-directed mutagenesis, co-immunoprecipitation\",\n      \"pmids\": [\"17635105\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Kinase responsible for S71/S74 phosphorylation not identified\", \"In vivo dynamics of phosphorylation cycle unknown\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Demonstrating that IRBIT coordinates pancreatic duct secretion by simultaneously activating basolateral pNBC1 and luminal CFTR through distinct domains, and separately activates NHE3 via CaMKII-dependent trafficking, established IRBIT as a master regulator of epithelial ion transport.\",\n      \"evidence\": \"siRNA knockdown, ion-selective microelectrodes, single-channel recordings, domain constructs for CFTR/pNBC1; co-IP and surface biotinylation for NHE3\",\n      \"pmids\": [\"19033647\", \"18829453\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis for distinct domain requirements for CFTR vs. pNBC1 unknown\", \"Whether IRBIT-NHE3 regulation operates in vivo not tested\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Discovery that IRBIT binds CPSF/Fip1 and inhibits poly(A) polymerase in a phosphorylation-dependent manner revealed an unexpected role outside ion transport, linking IRBIT to mRNA 3′-end processing and broadening its functional repertoire.\",\n      \"evidence\": \"Co-immunoprecipitation, RNA pulldown, in vitro PAP activity assay, immunofluorescence\",\n      \"pmids\": [\"19224921\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Target mRNAs regulated by IRBIT-mediated polyadenylation control not identified\", \"Physiological relevance of IRBIT-PAP inhibition in vivo not demonstrated\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Elucidation that IRBIT activates NBCe1-B by releasing an autoinhibitory domain, and that IRBIT antagonizes WNK/SPAK kinase signaling by recruiting PP1 to dephosphorylate CFTR and NBCe1-B for surface expression, established the molecular mechanism by which IRBIT orchestrates epithelial secretion through phosphatase/kinase balance.\",\n      \"evidence\": \"Two-electrode voltage clamp with deletion mutagenesis; siRNA epistasis, phosphoprotein analysis, co-IP for SPAK/PP1 pathway\",\n      \"pmids\": [\"22012331\", \"21317537\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural details of IRBIT-AID interaction unknown\", \"Whether IRBIT-PP1 axis operates in all IRBIT-regulated transporters untested\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Identification of a conserved positively charged regulatory module shared across NBCe1-B, NBCn1-A, CFTR, and Slc26a6 as the common IRBIT-binding motif, together with in vivo demonstration that IRBIT mediates Ca2+/cAMP synergy in pancreatic secretion using knockout mice, unified the mechanism of IRBIT-dependent transporter activation and validated it physiologically.\",\n      \"evidence\": \"Systematic mutagenesis and electrophysiology across multiple transporters; Irbit−/− and Slc26a6−/− mouse models with functional secretion assays\",\n      \"pmids\": [\"23431199\", \"23542070\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether the conserved module is sufficient for IRBIT regulation in all family members not fully tested\", \"Tissue-specific phenotypes of Irbit−/− mice beyond pancreas/salivary gland not characterized\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Discovery that IRBIT forms a dATP-dependent complex with ribonucleotide reductase to inhibit RNR activity and control dNTP pools revealed a fundamental role in nucleotide metabolism and cell cycle progression, far beyond calcium signaling.\",\n      \"evidence\": \"Co-IP, in vitro RNR activity assays, dNTP pool quantification, cell cycle analysis in IRBIT-depleted HeLa cells\",\n      \"pmids\": [\"25237103\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of dATP-dependent IRBIT-RNR complex unknown\", \"Whether RNR regulation is conserved across all IRBIT-expressing tissues untested\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Showing that IRBIT suppresses CaMKIIα kinase activity by blocking calmodulin binding, with IRBIT-deficient mice exhibiting elevated catecholamine levels and behavioral abnormalities, established IRBIT as a neuronal signaling modulator controlling dopaminergic function.\",\n      \"evidence\": \"Co-IP, kinase activity assays, IRBIT-deficient mouse behavioral analysis, TH phosphorylation measurements\",\n      \"pmids\": [\"25922519\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether CaMKIIα inhibition operates in non-neuronal tissues unclear\", \"Contribution of CaMKIIα inhibition vs. IP3R regulation to behavioral phenotype not dissected\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Demonstration that IRBIT and Bcl2l10 cooperate at mitochondria-associated membranes to regulate IP3R and that apoptotic stress-induced dephosphorylation converts IRBIT from a Bcl2l10 cooperator to an inhibitor, promoting ER-mitochondria Ca2+ transfer and apoptosis, linked IRBIT to programmed cell death.\",\n      \"evidence\": \"MAM fractionation, co-IP, Ca2+ release and apoptosis assays, dephosphorylation studies\",\n      \"pmids\": [\"27995898\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vivo relevance of IRBIT-Bcl2l10 axis in apoptosis not validated in animal models\", \"Identity of phosphatase responsible for apoptotic dephosphorylation of IRBIT unknown\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Detailed phosphoproteomic dissection of how IRBIT recruits PP1, SPAK, calcineurin, and CaMKII to control distinct phosphorylation sites on NBCe1-B that govern chloride sensitivity and active conformation revealed IRBIT as a multi-kinase/phosphatase scaffolding hub for transporter fine-tuning.\",\n      \"evidence\": \"Phosphoproteomics, systematic mutagenesis, electrophysiology, co-IP\",\n      \"pmids\": [\"30377224\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether the same multi-kinase scaffold operates on other IRBIT-regulated transporters not shown\", \"Structural basis of simultaneous scaffolding unknown\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Establishing that the IRBIT-RNR circuit controls intestinal stem cell differentiation in Drosophila, and that IRBIT activates NBCe1-B by competitively displacing the AID from the transmembrane domain via electrostatic interaction, refined both the developmental and biophysical understanding of IRBIT function.\",\n      \"evidence\": \"Drosophila genetic loss-of-function for RNR regulation; systematic charge-swap mutagenesis and electrophysiology in Xenopus oocytes for AID displacement mechanism\",\n      \"pmids\": [\"32179478\", \"33237573\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mammalian stem cell relevance of IRBIT-RNR axis not tested\", \"Whether AID displacement mechanism generalizes to other autoinhibited transporters unknown\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Discovery that AHCYL1 senses S-adenosyl-L-homocysteine via its C-terminus to inhibit PIK3C3 and suppress autophagy independently of MTORC1 revealed IRBIT as a metabolite sensor linking one-carbon metabolism to autophagy.\",\n      \"evidence\": \"SAH binding assays, PIK3C3 activity assays, autophagy assays, in vivo validation\",\n      \"pmids\": [\"33993848\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether SAH-sensing and IP3R regulation are coordinated or independent is unknown\", \"Structural basis of SAH binding to C-terminus not resolved\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Identification of NAD redox state as a modulator of IRBIT-dependent NBCe1-B activation, PREX2/RAC1 GEF activity enhancement by AHCYL1, and the IRBIT/LIMA1/DRA complex for stimulus-dependent Cl−/HCO3− exchange further expanded the scope of IRBIT as a context-dependent signaling integrator.\",\n      \"evidence\": \"Electrophysiology with NAD+/NADH modulation; LC-MS/MS pulldown with in vitro GEF assay; co-IP with siRNA knockdown and DRA activity measurements\",\n      \"pmids\": [\"39985648\", \"40365293\", \"40569378\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Physiological contexts where NAD redox state controls IRBIT function not defined\", \"PREX2 interaction validated only in NSCLC, generalizability unknown\", \"LIMA1-IRBIT-DRA complex structure and stoichiometry unresolved\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Definitive mapping of CK2-phosphorylated S80/S84/S85 as the primary IP3R-binding determinants of IRBIT, with computational modeling showing these residues mimic IP3 in the binding core, resolved a long-standing question about which phosphosites are directly responsible for pseudoligand function.\",\n      \"evidence\": \"In vitro kinase assays (PKA, CK2), pulldown with phosphomimetic mutants, Ca2+ imaging in living cells, computational docking\",\n      \"pmids\": [\"42032162\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Experimental high-resolution structure of IRBIT-IP3R complex not yet obtained\", \"How CK2 and PKA phosphorylation are coordinated in vivo remains unclear\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Key open questions include the structural basis of IRBIT's simultaneous scaffolding of multiple kinases/phosphatases, how IRBIT partitions among its many targets (IP3R, transporters, RNR, PAP, PIK3C3) in different cell types, and whether IRBIT loss-of-function causes a defined human Mendelian disorder.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No high-resolution structure of any IRBIT complex\", \"Target prioritization mechanism across diverse binding partners unknown\", \"No human genetic disease linked to AHCYL1 mutations identified in the literature\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [0, 1, 2, 5, 11, 15, 16, 25, 30]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [5, 6, 11, 14, 21, 31]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005783\", \"supporting_discovery_ids\": [18, 26]},\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [6, 13, 14, 24]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [7, 15]},\n      {\"term_id\": \"GO:0005739\", \"supporting_discovery_ids\": [18]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [0, 1, 2, 4, 9, 13, 16, 32]},\n      {\"term_id\": \"R-HSA-382551\", \"supporting_discovery_ids\": [3, 5, 6, 10, 11, 14, 21, 22, 31]},\n      {\"term_id\": \"R-HSA-9612973\", \"supporting_discovery_ids\": [25]},\n      {\"term_id\": \"R-HSA-5357801\", \"supporting_discovery_ids\": [18]},\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [15, 23]}\n    ],\n    \"complexes\": [\n      \"IRBIT-IP3R complex\",\n      \"IRBIT-RNR complex\",\n      \"IRBIT-CPSF/Fip1 complex\"\n    ],\n    \"partners\": [\n      \"ITPR1\",\n      \"SLC4A4\",\n      \"CFTR\",\n      \"SLC9A3\",\n      \"RRM1\",\n      \"BCL2L10\",\n      \"PIK3C3\",\n      \"PPP1CA\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}