{"gene":"ANO2","run_date":"2026-06-09T22:02:43","timeline":{"discoveries":[{"year":2009,"finding":"ANO2/TMEM16B forms a calcium-activated chloride channel (CaCC) when expressed in HEK-293 cells, exhibiting channel properties closely resembling the native olfactory CaCC. The protein was identified in a proteomic screen of cilial membrane proteins of mouse olfactory sensory neurons (OSNs), and ANO2::EGFP fusion protein localized to OSN cilia in vivo.","method":"Proteomic screen, adenoviral-mediated in vivo expression with fluorescence imaging, whole-cell patch-clamp electrophysiology in HEK-293 cells","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — direct patch-clamp functional assay combined with in vivo localization and proteomic identification; foundational paper replicated by multiple subsequent studies","pmids":["19561302"],"is_preprint":false},{"year":2009,"finding":"TMEM16B (ANO2) confers Ca2+-dependent chloride currents when overexpressed in mammalian cells. In mouse retina, TMEM16B localizes to photoreceptor synaptic terminals and co-localizes with presynaptic adaptor proteins PSD95, VELI3, and MPP4 at ribbon synapses via a PDZ class I binding motif. TMEM16B is lost from photoreceptor membranes in MPP4-deficient mice, indicating MPP4-dependent recruitment to specialized plasma membrane domains.","method":"Halide-sensitive fluorescent protein assay, whole-cell patch-clamp, immunohistochemistry, co-localization, MPP4 knockout mouse analysis","journal":"The Journal of neuroscience : the official journal of the Society for Neuroscience","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — functional electrophysiology combined with in vivo localization and genetic knockout evidence for complex membership","pmids":["19474308"],"is_preprint":false},{"year":2009,"finding":"Mouse TMEM16B expressed in HEK 293T cells is directly gated by intracellular Ca2+, as demonstrated in inside-out excised patches where controlled Ca2+ concentrations rapidly activated the channel. Ca2+ concentration for half-maximal activation decreased from 4.9 µM at -50 mV to 3.3 µM at +50 mV with Hill coefficient >2, indicating cooperative Ca2+ binding. The channel is anion-selective and blocked by niflumic acid.","method":"Whole-cell and inside-out patch-clamp electrophysiology in HEK 293T cells, caged Ca2+ photolysis, G-protein-coupled receptor Ca2+ release","journal":"Pflugers Archiv : European journal of physiology","confidence":"High","confidence_rationale":"Tier 1 / Strong — rigorous in vitro reconstitution with direct Ca2+ application in excised patches and multiple activation modalities","pmids":["19475416"],"is_preprint":false},{"year":2010,"finding":"Endogenous Tmem16b protein is specifically and highly expressed in the cilia of olfactory sensory neurons (OSNs) in the olfactory epithelium, as established by proteome analysis of the olfactory epithelium membrane fraction and confirmed by additional localization studies. Expression is specific to OSNs, in contrast to the broad expression of Tmem16a.","method":"Membrane proteome analysis, immunohistochemistry/localization in native olfactory epithelium","journal":"Chemical senses","confidence":"Medium","confidence_rationale":"Tier 2–3 / Strong — native tissue proteomics combined with localization, replicated across multiple labs","pmids":["20100788"],"is_preprint":false},{"year":2010,"finding":"TMEM16B/ANO2 expressed in HEK 293T cells displays electrophysiological properties (anion selectivity, blocker sensitivity, Ca2+-activated kinetics) closely matching the native Ca2+-activated Cl- current in isolated mouse olfactory sensory neurons, including dynamic ion selectivity measured by rapid Ca2+ concentration jumps. TMEM16B/ANO2 co-localizes with adenylyl cyclase III at the olfactory epithelium surface, placing it in the olfactory transduction compartment.","method":"Whole-cell voltage-clamp with caged Ca2+ photolysis, extracellular blocker application, ion substitution, immunohistochemistry","journal":"The Journal of physiology","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — direct comparison of heterologous and native channels with multiple orthogonal electrophysiological and pharmacological methods","pmids":["20837642"],"is_preprint":false},{"year":2012,"finding":"Glutamate residues E367 and 386EEEEE390 in the first putative intracellular loop of TMEM16B play an important role in voltage dependence of the channel; mutations at these sites shift the conductance-voltage relationship toward more positive voltages without greatly affecting Ca2+ affinity.","method":"Site-directed mutagenesis, whole-cell voltage-clamp in HEK 293T cells at various intracellular Ca2+ concentrations","journal":"The Journal of general physiology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — rigorous site-directed mutagenesis with functional electrophysiology; single lab but multiple mutants tested with clear structure-function conclusions","pmids":["22412191"],"is_preprint":false},{"year":2013,"finding":"Using TMEM16A/TMEM16B chimeric channels, the third intracellular loop of TMEM16B (equivalent region in TMEM16A) was identified as the site controlling Ca2+ sensitivity, while the C-terminal region including TMD7-8 controls the rate of channel opening and closing. Deletion of the TMEM16A C-terminus (77 aa) accelerated kinetics, confirming the C-terminal role.","method":"Chimeric protein construction, whole-cell patch-clamp in transfected mammalian cells, C-terminal deletion mutagenesis","journal":"The Biochemical journal","confidence":"High","confidence_rationale":"Tier 1 / Moderate — systematic chimera and deletion approach with functional readout; single lab with multiple orthogonal constructs","pmids":["23570556"],"is_preprint":false},{"year":2013,"finding":"TMEM16B localizes specifically to the cilia of mature olfactory sensory neurons throughout development (from E14.5 onward), consistent with a role in olfactory signal transduction during and after development.","method":"Immunohistochemistry on mouse olfactory epithelium at multiple prenatal and postnatal stages","journal":"Developmental neurobiology","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — localization-only study in native tissue, replicated across multiple developmental stages, consistent with other localization studies","pmids":["24318978"],"is_preprint":false},{"year":2014,"finding":"TMEM16B gating is modulated by permeant anions: anions more permeant than Cl- slow both activation and deactivation kinetics, while less permeant anions accelerate them. Extracellular or intracellular SCN- shifts the voltage dependence of activation to more negative potentials and increases apparent Ca2+ affinity. This provides evidence that ion permeation and gating are coupled processes in TMEM16B.","method":"Whole-cell and inside-out patch-clamp with systematic anion substitution, dose-response Ca2+ analysis in HEK 293T cells","journal":"The Journal of general physiology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — rigorous electrophysiology with systematic ion substitution experiments; single lab, multiple orthogonal approaches","pmids":["24863931"],"is_preprint":false},{"year":2015,"finding":"TMEM16A and TMEM16B display intrinsic dual (fast and slow) gating modes regulated by voltage and extracellular chloride. Mutating residues 480RSQ482 to AVK in the first intracellular loop of TMEM16B nearly abolished slow gating, identifying this loop as a determinant of the slow gating mode.","method":"Whole-cell and inside-out patch-clamp with long depolarizing pulses, site-directed mutagenesis, recordings from parotid acinar cells","journal":"The Journal of physiology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — mutagenesis combined with functional electrophysiology in both heterologous and native cell systems","pmids":["26728431"],"is_preprint":false},{"year":2015,"finding":"Extracellular anthracene-9-carboxylic acid (A9C) causes voltage-dependent block of outward currents through TMEM16B and, at low Ca2+ (1.5 µM), potentiates tail currents and prolongs deactivation kinetics. The non-charged analogue A9M produces only small voltage-independent block without potentiation, demonstrating that the negative charge of A9C is required for both voltage-dependent block and potentiation.","method":"Whole-cell patch-clamp pharmacology in HEK 293T cells at multiple Ca2+ concentrations and voltages","journal":"Biochimica et biophysica acta","confidence":"Medium","confidence_rationale":"Tier 1–2 / Weak — rigorous electrophysiology with charge-matched analogue control; single lab, single method","pmids":["25620774"],"is_preprint":false},{"year":2016,"finding":"TMEM16B KO mice show abolition of Ca2+-activated Cl- currents in olfactory sensory neurons, increased action potential firing (prolonged responses with more APs) upon odorant stimulation, reduced basal spiking in I7-expressing neurons, and supernumerary I7 glomeruli in the olfactory bulb, demonstrating that TMEM16B controls AP firing pattern and correct axonal targeting of OSNs.","method":"TMEM16B knockout mouse, suction electrode and loose-patch recordings from isolated OSNs and olfactory epithelium slices, behavioral olfactory testing, glomerular mapping","journal":"The Journal of general physiology","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic KO with multiple electrophysiological recording modalities, behavioral readout, and anatomical analysis","pmids":["27619419"],"is_preprint":false},{"year":2016,"finding":"ANO2/TMEM16B is expressed in the basolateral membrane of the retinal pigment epithelium (RPE), and siRNA knockdown of ANO2 reduces both Ca2+-dependent chloride conductance and ANO2 protein expression in primary mouse RPE cells and ARPE-19 cells, establishing ANO2 as a contributor to the Ca2+-activated Cl- channel current in RPE.","method":"Confocal immunohistochemistry on retinal sections, siRNA knockdown, whole-cell patch-clamp, Western blot, PCR","journal":"Experimental eye research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — siRNA knockdown with direct electrophysiological readout and protein quantification; single lab, multiple orthogonal methods","pmids":["27940219"],"is_preprint":false},{"year":2017,"finding":"PIP2 inhibits TMEM16B channel activity (~0.2-fold) while activating TMEM16A. PIP2 modulation of TMEM16B does not vary over broad Ca2+ ranges but is only detectable at highly depolarized potentials. A voltage-sensitive phosphatase (DrVSP) that degrades PIP2 enhanced TMEM16B currents; this effect was abolished by an inactivating DrVSP mutation or counteracted by PI(4)P 5-kinase co-expression. Modulation is due to changes in channel gating, not single-channel conductance.","method":"Whole-cell patch-clamp with soluble PIP2 analogue (diC8-PIP2), DrVSP co-expression, PI(4)P 5-kinase co-expression, inactivating DrVSP mutant control","journal":"British journal of pharmacology","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — multiple genetic and pharmacological tools for PIP2 manipulation with functional electrophysiology; single lab, orthogonal approaches","pmids":["28616863"],"is_preprint":false},{"year":2017,"finding":"In inferior olivary (IO) neurons, Ca2+ influx through dendritic high-threshold voltage-gated Ca2+ channels activates TMEM16B-mediated CaCCs, which contribute to membrane repolarization. Loss of TMEM16B in knockout mice abolishes CaCCs in IO neurons, leading to markedly diminished AP firing of IO neurons and severe cerebellar motor learning deficits.","method":"TMEM16B knockout mouse, whole-cell patch-clamp in IO neurons, behavioral cerebellar motor learning tests","journal":"Neuron","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic KO with direct electrophysiology in native neurons and behavioral phenotyping; single lab but multiple orthogonal approaches","pmids":["28858616"],"is_preprint":false},{"year":2017,"finding":"Residues R573 and K540 at the entrance and inside the putative pore of TMEM16B control ion permeability in a side-of-membrane and activation-level dependent manner. R573 mutation abolishes the anomalous mole fraction effect observed with permeant anions and alters apparent Ca2+ sensitivity, indicating that pore-facing residues control both ion selectivity and gating.","method":"Site-directed mutagenesis of R573 and K540, whole-cell and inside-out patch-clamp in HEK-293 cells","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — rigorous mutagenesis with functional electrophysiology but single lab, single paper","pmids":["28046119"],"is_preprint":false},{"year":2017,"finding":"TMEM16A and TMEM16B can form heteromeric channels in addition to homomeric channels in pinealocytes. Co-expression of both subunits or a tandem TMEM16A-TMEM16B construct in HEK293 cells recapitulates the electrophysiological characteristics of native pineal CaCCs. Both channels contribute to ClCa currents in pinealocytes, which regulate melatonin secretion.","method":"Bimolecular fluorescence complementation (BiFC), FRET, co-immunoprecipitation, tandem channel expression in HEK293, siRNA knockdown, whole-cell patch-clamp, melatonin secretion assay","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — three orthogonal methods for heteromeric complex (BiFC, FRET, co-IP) plus functional reconstitution; single lab","pmids":["29187602"],"is_preprint":false},{"year":2019,"finding":"TMEM16B (ANO2) is the dominant Ca2+-activated Cl- channel subunit in intestinal vagal afferents of nodose neurons and is required for cholecystokinin (CCK)-induced satiety. Heterozygous TMEM16B KO reduces CCK-induced current, CCK-induced satiety, and energy expenditure, producing an obese phenotype. TMEM16B expression is reduced in nodose neurons of obese high-fat diet mice.","method":"Whole-cell patch-clamp in nodose neurons, TMEM16B heterozygous KO mouse, behavioral feeding/satiety assays, metabolic measurements, high-fat diet model","journal":"JCI insight","confidence":"High","confidence_rationale":"Tier 2 / Moderate — genetic KO with direct electrophysiology in native neurons and multiple behavioral/metabolic readouts; single lab","pmids":["30843875"],"is_preprint":false},{"year":2019,"finding":"TMEM16B in lateral septum (LS) neurons regulates spike frequency and spike frequency adaptation. Loss of TMEM16B alters neurotransmitter release at the hippocampal-LS synapse and leads to lengthened aggressive behavior in male mice during resident-intruder testing.","method":"Whole-cell patch-clamp in LS neurons, TMEM16B KO mouse, resident-intruder behavioral paradigm","journal":"The Journal of neuroscience : the official journal of the Society for Neuroscience","confidence":"High","confidence_rationale":"Tier 2 / Moderate — genetic KO with direct electrophysiology in native neurons and behavioral quantification; single lab, two orthogonal approaches","pmids":["31320449"],"is_preprint":false},{"year":2021,"finding":"The TRPV4 antagonist GSK2193874 enhances chloride currents mediated by TMEM16B expressed in HEK cells at nanomolar concentrations, and the TRPV4 agonist GSK1016790A enhances native CaCCs in Xenopus oocytes, identifying these compounds as positive modulators of TMEM16B-mediated currents.","method":"Whole-cell patch-clamp in HEK cells expressing TMEM16B, native CaCC recordings in Xenopus oocytes","journal":"Biochemistry and biophysics reports","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — direct electrophysiology in heterologous and native systems; single lab, single paper","pmids":["34917777"],"is_preprint":false},{"year":2024,"finding":"CLCA4 (Ca2+-activated Cl- channel regulator 4) potentiates TMEM16B channel activity. The N-terminal portion of CLCA4 (N-CLCA4) after self-cleavage is secreted and its von Willebrand factor type A (VWA) domain is sufficient to increase ICaCC carried by TMEM16B in HEK293T cells. This interaction is mediated by the metal ion-dependent adhesion site (MIDAS) motif within VWA, defining a specific CLCA4-TMEM16B regulatory pair distinct from the CLCA1-TMEM16A pair.","method":"Overexpression in HEK293T cells, domain deletion constructs, MIDAS motif mutagenesis, whole-cell patch-clamp","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional electrophysiology with domain mapping and motif mutagenesis; single lab but multiple constructs","pmids":["38825009"],"is_preprint":false},{"year":2024,"finding":"In TMEM16B knockout OSNs, while basic membrane properties (input resistance, resting potential, voltage-gated currents) are unchanged, TMEM16B determines the time required for the odorant response to reach its peak and to terminate after stimulation. Absence of TMEM16B causes faster response termination, allowing KO OSNs to fire action potentials more reliably during rapid repeated stimulation. The CNG channel predominantly controls response delay and adaptation, while TMEM16B controls response kinetics and amplitude amplification.","method":"TMEM16B knockout mouse, suction electrode and whole-cell patch-clamp recordings from isolated OSNs and epithelial slices, odorant stimulation protocols","journal":"The Journal of physiology","confidence":"High","confidence_rationale":"Tier 2 / Moderate — genetic KO with multiple electrophysiological recording configurations in native neurons; single lab but orthogonal approaches","pmids":["39167717"],"is_preprint":false},{"year":2024,"finding":"In TMEM16B knockout mice, olfactory sensory representations are denser and OSN response magnitudes are increased (measured by multiphoton microscopy), and animals show increased aversion to trimethylamine and decreased efficiency in olfactory-guided navigation, indicating TMEM16B sparsens peripheral olfactory sensory representations.","method":"TMEM16B knockout mouse, multiphoton microscopy of OSN activity in olfactory epithelium, behavioral olfactory-guided navigation and odor aversion assays","journal":"bioRxiv","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — genetic KO with in vivo imaging and behavioral readouts; preprint, single lab","pmids":[],"is_preprint":true}],"current_model":"ANO2/TMEM16B is a calcium-activated chloride channel (CaCC) that localizes to the cilia of olfactory sensory neurons, photoreceptor synaptic terminals, retinal pigment epithelium, inferior olivary neurons, lateral septal neurons, and intestinal vagal afferents, where it amplifies odorant-evoked currents and shapes action potential firing kinetics; its gating is cooperatively regulated by intracellular Ca2+ (EC50 ~3–5 µM) and membrane voltage, with permeant anions coupling gating to permeation, and key structural determinants identified include the third intracellular loop (Ca2+ sensitivity), C-terminal/TMD7-8 region (kinetics), first intracellular loop residues (voltage dependence and slow gating), and pore residues R573/K540 (ion selectivity); the channel is inhibited by PIP2 depletion, potentiated by CLCA4, and can form heteromeric complexes with TMEM16A."},"narrative":{"mechanistic_narrative":"ANO2/TMEM16B is a calcium-activated chloride channel (CaCC) that shapes neuronal signaling kinetics across multiple sensory and neural circuits [PMID:19561302, PMID:27619419]. It was identified in the ciliary membrane of olfactory sensory neurons, where it generates a current closely matching the native olfactory CaCC and amplifies odorant-evoked responses [PMID:19561302, PMID:20837642]; in knockout mice it controls the kinetics and amplitude of the odorant response, governing action potential firing patterns, response termination, and correct axonal targeting of OSNs to olfactory bulb glomeruli [PMID:27619419, PMID:39167717]. The channel is directly gated by intracellular Ca2+ in a cooperative, voltage-dependent manner (half-maximal activation ~3–5 µM) and is anion-selective [PMID:19475416]. Structure–function studies localize Ca2+ sensitivity to the third intracellular loop, gating kinetics to the C-terminal/TMD7-8 region, voltage dependence and slow gating to first intracellular loop residues, and ion selectivity to pore residues R573/K540, with permeant anions coupling gating to permeation [PMID:22412191, PMID:23570556, PMID:24863931, PMID:26728431, PMID:28046119]. ANO2 activity is inhibited by PIP2 and potentiated by the secreted VWA domain of CLCA4 acting through its MIDAS motif [PMID:28616863, PMID:38825009], and ANO2 forms both homomeric and heteromeric channels with TMEM16A [PMID:29187602]. Beyond olfaction, ANO2 supplies CaCC currents that shape firing and circuit output in photoreceptor ribbon synapses, retinal pigment epithelium, inferior olivary neurons, lateral septal neurons, and intestinal vagal afferents, where its loss produces deficits in cerebellar motor learning, aggression behavior, and CCK-induced satiety [PMID:19474308, PMID:27940219, PMID:28858616, PMID:30843875, PMID:31320449].","teleology":[{"year":2009,"claim":"Establishing the molecular identity of the long-sought native olfactory calcium-activated chloride channel, the question was which gene product carries this current; ANO2/TMEM16B was identified as a CaCC residing in OSN cilia.","evidence":"Ciliary membrane proteomics, in vivo EGFP-fusion localization, and whole-cell patch-clamp in HEK-293 cells","pmids":["19561302"],"confidence":"High","gaps":["Single-channel and structural basis of gating not resolved","Physiological necessity in vivo not yet tested by knockout"]},{"year":2009,"claim":"To define how ANO2 is targeted to functional sites beyond cilia, its retinal localization and recruitment mechanism were examined, placing it at photoreceptor ribbon synapses via a PDZ-dependent scaffold.","evidence":"Halide-sensitive fluorescent assay, patch-clamp, immunohistochemistry, co-localization with PSD95/VELI3/MPP4, and MPP4 knockout mouse","pmids":["19474308"],"confidence":"High","gaps":["Functional role of ANO2 in synaptic transmission not directly measured","PDZ partner directly binding ANO2 not biochemically isolated"]},{"year":2009,"claim":"To distinguish direct Ca2+ gating from indirect activation, ANO2 was tested in excised patches with controlled Ca2+, demonstrating direct cooperative Ca2+ activation with mild voltage dependence.","evidence":"Inside-out and whole-cell patch-clamp with caged Ca2+ photolysis in HEK 293T cells","pmids":["19475416"],"confidence":"High","gaps":["Structural Ca2+-binding site not identified","Mechanism of cooperativity unresolved"]},{"year":2010,"claim":"To confirm ANO2 is the native olfactory CaCC rather than a mimic, heterologous and native currents were directly compared and ANO2 was placed in the transduction compartment alongside adenylyl cyclase III.","evidence":"Native OSN proteomics, immunohistochemistry, and voltage-clamp with rapid Ca2+ jumps comparing heterologous and native channels","pmids":["20100788","20837642"],"confidence":"High","gaps":["Quantitative contribution to odor signal amplification not yet established in vivo"]},{"year":2012,"claim":"To map the channel's voltage sensitivity, acidic residues in the first intracellular loop were mutated, identifying E367 and 386EEEEE390 as determinants of voltage dependence separable from Ca2+ affinity.","evidence":"Site-directed mutagenesis and whole-cell voltage-clamp across Ca2+ concentrations in HEK 293T cells","pmids":["22412191"],"confidence":"High","gaps":["Whether these residues form a voltage sensor or modulate Ca2+-coupled gating not distinguished"]},{"year":2013,"claim":"To dissect which domains govern Ca2+ sensitivity versus kinetics, TMEM16A/B chimeras and deletions localized Ca2+ sensitivity to the third intracellular loop and gating kinetics to the C-terminal/TMD7-8 region.","evidence":"Chimeric construct and C-terminal deletion analysis with whole-cell patch-clamp","pmids":["23570556"],"confidence":"High","gaps":["Atomic-resolution structure of these regions in ANO2 absent"]},{"year":2014,"claim":"To probe whether permeation and gating are coupled, systematic anion substitution showed permeant anions tune activation/deactivation kinetics and apparent Ca2+ affinity, establishing permeation-gating coupling.","evidence":"Whole-cell and inside-out patch-clamp with anion substitution and Ca2+ dose-response in HEK 293T cells","pmids":["24863931"],"confidence":"High","gaps":["Pore residues mediating anion-gating coupling not yet pinpointed in this study"]},{"year":2015,"claim":"To resolve the determinants of distinct gating modes, dual fast/slow gating was characterized and 480RSQ482 in the first intracellular loop identified as required for slow gating.","evidence":"Patch-clamp with long depolarizing pulses, mutagenesis, and recordings from parotid acinar cells","pmids":["26728431"],"confidence":"High","gaps":["Physiological significance of slow gating mode in native neurons unclear"]},{"year":2015,"claim":"To define a charged pharmacological probe of gating, A9C was shown to produce charge-dependent voltage-dependent block and potentiation, using the uncharged A9M analogue as control.","evidence":"Whole-cell patch-clamp pharmacology at multiple Ca2+ and voltage conditions in HEK 293T cells","pmids":["25620774"],"confidence":"Medium","gaps":["Binding site of A9C not mapped","Single lab, single method"]},{"year":2016,"claim":"To establish in vivo function in olfaction, TMEM16B knockout mice were used to show loss of OSN CaCCs alters AP firing patterns, basal spiking, and glomerular axon targeting.","evidence":"Knockout mouse with suction/loose-patch recordings, behavioral testing, and glomerular mapping","pmids":["27619419"],"confidence":"High","gaps":["Mechanism linking channel activity to axon guidance not defined"]},{"year":2016,"claim":"To extend ANO2's role beyond neurons, it was shown to contribute Ca2+-activated Cl- conductance in retinal pigment epithelium via siRNA knockdown.","evidence":"Immunohistochemistry, siRNA knockdown, patch-clamp, and Western blot in primary and ARPE-19 cells","pmids":["27940219"],"confidence":"Medium","gaps":["Physiological RPE function of ANO2 current not established","Knockdown partial"]},{"year":2017,"claim":"To identify lipid regulation, PIP2 was shown to inhibit ANO2 (opposite to TMEM16A) through gating changes, using a voltage-sensitive phosphatase and kinase manipulation.","evidence":"Whole-cell patch-clamp with diC8-PIP2, DrVSP co-expression with inactivating control, and PI(4)P 5-kinase","pmids":["28616863"],"confidence":"High","gaps":["PIP2 interaction site on ANO2 not mapped","Effect only detectable at depolarized potentials"]},{"year":2017,"claim":"To extend ANO2's circuit role, knockout studies showed it carries dendritic CaCCs in inferior olivary neurons that drive repolarization, firing, and cerebellar motor learning.","evidence":"Knockout mouse with patch-clamp in IO neurons and behavioral motor learning tests","pmids":["28858616"],"confidence":"High","gaps":["Coupling between specific voltage-gated Ca2+ channels and ANO2 not molecularly defined"]},{"year":2017,"claim":"To localize pore selectivity determinants, mutagenesis of R573 and K540 showed these residues control ion permeability, the anomalous mole fraction effect, and apparent Ca2+ sensitivity.","evidence":"Site-directed mutagenesis with whole-cell and inside-out patch-clamp in HEK-293 cells","pmids":["28046119"],"confidence":"Medium","gaps":["Structural model of pore geometry absent","Single lab, single paper"]},{"year":2017,"claim":"To test subunit assembly, ANO2 was shown to form heteromeric channels with TMEM16A in pinealocytes, contributing to melatonin-regulating CaCC currents.","evidence":"BiFC, FRET, co-immunoprecipitation, tandem construct expression, siRNA, patch-clamp, and melatonin secretion assay","pmids":["29187602"],"confidence":"High","gaps":["Stoichiometry and physiological prevalence of heteromers in other tissues unknown"]},{"year":2019,"claim":"To uncover a metabolic role, ANO2 was identified as the dominant CaCC in vagal nodose afferents required for CCK-induced satiety, with heterozygous loss producing obesity.","evidence":"Patch-clamp in nodose neurons, heterozygous knockout mouse, feeding/satiety and metabolic assays, high-fat diet model","pmids":["30843875"],"confidence":"High","gaps":["Signaling link between CCK receptor activation and ANO2 not fully resolved"]},{"year":2019,"claim":"To assess central circuit function, ANO2 in lateral septum neurons was shown to regulate spike frequency adaptation and synaptic neurotransmitter release, with loss prolonging aggressive behavior.","evidence":"Patch-clamp in LS neurons, knockout mouse, and resident-intruder behavioral paradigm","pmids":["31320449"],"confidence":"High","gaps":["Mechanism of presynaptic modulation unresolved"]},{"year":2021,"claim":"To find positive pharmacological modulators, TRPV4 ligands GSK2193874 and GSK1016790A were shown to enhance ANO2-mediated and native CaCC currents.","evidence":"Patch-clamp in HEK cells and native CaCC recordings in Xenopus oocytes","pmids":["34917777"],"confidence":"Medium","gaps":["Binding site and selectivity over TRPV4 not established","Single lab, single paper"]},{"year":2024,"claim":"To identify a protein regulator, CLCA4 was shown to potentiate ANO2 via its secreted self-cleaved VWA domain acting through the MIDAS motif, defining a CLCA4-ANO2 pair.","evidence":"Overexpression with domain deletion and MIDAS mutagenesis and whole-cell patch-clamp in HEK293T cells","pmids":["38825009"],"confidence":"Medium","gaps":["Endogenous CLCA4-ANO2 interaction in native tissue not shown","Structural basis of potentiation unknown"]},{"year":2024,"claim":"To refine ANO2's role in olfactory coding, knockout studies separated its function (response kinetics and amplitude) from CNG channel function (delay and adaptation), showing ANO2 sparsens sensory representations.","evidence":"Knockout mouse with suction/whole-cell recordings and multiphoton in vivo imaging plus behavioral navigation/aversion assays (one preprint)","pmids":["39167717"],"confidence":"High","gaps":["In vivo imaging behavioral findings partly in preprint form","Circuit-level consequences of denser representations not fully characterized"]},{"year":null,"claim":"An atomic structure of ANO2 defining the Ca2+-binding pocket, anion pore, voltage-coupling elements, and the molecular basis of its lipid and CLCA4 regulation remains to be determined.","evidence":"","pmids":[],"confidence":"High","gaps":["No experimentally determined ANO2 structure in the corpus","Direct PIP2 and CLCA4 binding sites unmapped","Heteromer stoichiometry in native tissues unknown"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0005215","term_label":"transporter activity","supporting_discovery_ids":[0,2,4]},{"term_id":"GO:0140299","term_label":"molecular sensor activity","supporting_discovery_ids":[2,5,8]}],"localization":[{"term_id":"GO:0005929","term_label":"cilium","supporting_discovery_ids":[0,3,7]},{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[1,12]}],"pathway":[{"term_id":"R-HSA-112316","term_label":"Neuronal System","supporting_discovery_ids":[11,14,18,21]},{"term_id":"R-HSA-9709957","term_label":"Sensory Perception","supporting_discovery_ids":[0,21,22]},{"term_id":"R-HSA-382551","term_label":"Transport of small molecules","supporting_discovery_ids":[2,8]}],"complexes":["TMEM16A-TMEM16B heteromeric channel"],"partners":["TMEM16A","CLCA4","MPP4","PSD95","VELI3"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9NQ90","full_name":"Anoctamin-2","aliases":["Transmembrane protein 16B"],"length_aa":998,"mass_kda":113.4,"function":"Calcium-activated chloride channel (CaCC) which may play a role in olfactory signal transduction. Odorant molecules bind to odor-sensing receptors (OSRs), leading to an increase in calcium entry that activates CaCC current which amplifies the depolarization of the OSR cells, ANO2 seems to be the underlying chloride channel involved in this process. May mediate light perception amplification in retina","subcellular_location":"Cell membrane","url":"https://www.uniprot.org/uniprotkb/Q9NQ90/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/ANO2","classification":"Not Classified","n_dependent_lines":2,"n_total_lines":1090,"dependency_fraction":0.001834862385321101},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/ANO2","total_profiled":1310},"omim":[{"mim_id":"619963","title":"ANOCTAMIN 9; ANO9","url":"https://www.omim.org/entry/619963"},{"mim_id":"610109","title":"ANOCTAMIN 2; ANO2","url":"https://www.omim.org/entry/610109"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Plasma membrane","reliability":"Supported"},{"location":"Nucleoplasm","reliability":"Additional"}],"tissue_specificity":"Tissue enriched","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"retina","ntpm":190.9}],"url":"https://www.proteinatlas.org/search/ANO2"},"hgnc":{"alias_symbol":[],"prev_symbol":["C12orf3","TMEM16B"]},"alphafold":{"accession":"Q9NQ90","domains":[{"cath_id":"3.30.70","chopping":"99-108_148-206_274-316","consensus_level":"medium","plddt":83.2318,"start":99,"end":316}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9NQ90","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9NQ90-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9NQ90-F1-predicted_aligned_error_v6.png","plddt_mean":73.62},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=ANO2","jax_strain_url":"https://www.jax.org/strain/search?query=ANO2"},"sequence":{"accession":"Q9NQ90","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9NQ90.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9NQ90/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9NQ90"}},"corpus_meta":[{"pmid":"19561302","id":"PMC_19561302","title":"ANO2 is the cilial calcium-activated chloride channel that may mediate olfactory amplification.","date":"2009","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/19561302","citation_count":265,"is_preprint":false},{"pmid":"19474308","id":"PMC_19474308","title":"TMEM16B, a novel protein with calcium-dependent chloride channel activity, associates with a presynaptic protein complex in photoreceptor terminals.","date":"2009","source":"The Journal of neuroscience : the official journal of the Society for Neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/19474308","citation_count":186,"is_preprint":false},{"pmid":"19475416","id":"PMC_19475416","title":"TMEM16B induces chloride currents activated by calcium in mammalian cells.","date":"2009","source":"Pflugers Archiv : European journal of physiology","url":"https://pubmed.ncbi.nlm.nih.gov/19475416","citation_count":181,"is_preprint":false},{"pmid":"27219012","id":"PMC_27219012","title":"Ani9, A Novel Potent Small-Molecule ANO1 Inhibitor with Negligible Effect on ANO2.","date":"2016","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/27219012","citation_count":170,"is_preprint":false},{"pmid":"12739008","id":"PMC_12739008","title":"FLJ10261 gene, located within the CCND1-EMS1 locus on human chromosome 11q13, encodes the eight-transmembrane protein homologous to C12orf3, C11orf25 and FLJ34272 gene products.","date":"2003","source":"International journal of oncology","url":"https://pubmed.ncbi.nlm.nih.gov/12739008","citation_count":146,"is_preprint":false},{"pmid":"20100788","id":"PMC_20100788","title":"Tmem16b is specifically expressed in the cilia of olfactory sensory neurons.","date":"2010","source":"Chemical senses","url":"https://pubmed.ncbi.nlm.nih.gov/20100788","citation_count":80,"is_preprint":false},{"pmid":"20837642","id":"PMC_20837642","title":"Calcium concentration jumps reveal dynamic ion selectivity of calcium-activated chloride currents in mouse olfactory sensory neurons and TMEM16b-transfected HEK 293T cells.","date":"2010","source":"The Journal of physiology","url":"https://pubmed.ncbi.nlm.nih.gov/20837642","citation_count":61,"is_preprint":false},{"pmid":"28616863","id":"PMC_28616863","title":"Contrasting effects of phosphatidylinositol 4,5-bisphosphate on cloned TMEM16A and TMEM16B channels.","date":"2017","source":"British journal of pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/28616863","citation_count":53,"is_preprint":false},{"pmid":"27619419","id":"PMC_27619419","title":"The Ca2+-activated Cl- channel TMEM16B regulates action potential firing and axonal targeting in olfactory sensory neurons.","date":"2016","source":"The Journal of general physiology","url":"https://pubmed.ncbi.nlm.nih.gov/27619419","citation_count":52,"is_preprint":false},{"pmid":"21984732","id":"PMC_21984732","title":"The anoctamin family: TMEM16A and TMEM16B as calcium-activated chloride channels.","date":"2011","source":"Experimental physiology","url":"https://pubmed.ncbi.nlm.nih.gov/21984732","citation_count":47,"is_preprint":false},{"pmid":"28858616","id":"PMC_28858616","title":"Inferior Olivary TMEM16B Mediates Cerebellar Motor Learning.","date":"2017","source":"Neuron","url":"https://pubmed.ncbi.nlm.nih.gov/28858616","citation_count":46,"is_preprint":false},{"pmid":"23570556","id":"PMC_23570556","title":"TMEM16A-TMEM16B chimaeras to investigate the structure-function relationship of calcium-activated chloride channels.","date":"2013","source":"The Biochemical journal","url":"https://pubmed.ncbi.nlm.nih.gov/23570556","citation_count":37,"is_preprint":false},{"pmid":"26728431","id":"PMC_26728431","title":"Gating modes of calcium-activated chloride channels TMEM16A and TMEM16B.","date":"2015","source":"The Journal of physiology","url":"https://pubmed.ncbi.nlm.nih.gov/26728431","citation_count":36,"is_preprint":false},{"pmid":"22412191","id":"PMC_22412191","title":"The voltage dependence of the TMEM16B/anoctamin2 calcium-activated chloride channel is modified by mutations in the first putative intracellular loop.","date":"2012","source":"The Journal of general physiology","url":"https://pubmed.ncbi.nlm.nih.gov/22412191","citation_count":35,"is_preprint":false},{"pmid":"24863931","id":"PMC_24863931","title":"Interactions between permeation and gating in the TMEM16B/anoctamin2 calcium-activated chloride channel.","date":"2014","source":"The Journal of general physiology","url":"https://pubmed.ncbi.nlm.nih.gov/24863931","citation_count":33,"is_preprint":false},{"pmid":"17371490","id":"PMC_17371490","title":"A common 253-kb deletion involving VWF and TMEM16B in German and Italian patients with severe von Willebrand disease type 3.","date":"2007","source":"Journal of thrombosis and haemostasis : JTH","url":"https://pubmed.ncbi.nlm.nih.gov/17371490","citation_count":32,"is_preprint":false},{"pmid":"29187602","id":"PMC_29187602","title":"TMEM16A and TMEM16B channel proteins generate Ca2+-activated Cl- current and regulate melatonin secretion in rat pineal glands.","date":"2017","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/29187602","citation_count":29,"is_preprint":false},{"pmid":"27940219","id":"PMC_27940219","title":"Anoctamin2 (TMEM16B) forms the Ca2+-activated Cl- channel in the retinal pigment epithelium.","date":"2016","source":"Experimental eye research","url":"https://pubmed.ncbi.nlm.nih.gov/27940219","citation_count":25,"is_preprint":false},{"pmid":"24318978","id":"PMC_24318978","title":"Developmental expression of the calcium-activated chloride channels TMEM16A and TMEM16B in the mouse olfactory epithelium.","date":"2013","source":"Developmental neurobiology","url":"https://pubmed.ncbi.nlm.nih.gov/24318978","citation_count":21,"is_preprint":false},{"pmid":"31320449","id":"PMC_31320449","title":"TMEM16B Calcium-Activated Chloride Channels Regulate Action Potential Firing in Lateral Septum and Aggression in Male Mice.","date":"2019","source":"The Journal of neuroscience : the official journal of the Society for Neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/31320449","citation_count":20,"is_preprint":false},{"pmid":"25620774","id":"PMC_25620774","title":"Multiple effects of anthracene-9-carboxylic acid on the TMEM16B/anoctamin2 calcium-activated chloride channel.","date":"2015","source":"Biochimica et biophysica acta","url":"https://pubmed.ncbi.nlm.nih.gov/25620774","citation_count":18,"is_preprint":false},{"pmid":"26530828","id":"PMC_26530828","title":"Expression of calcium-activated chloride channels Ano1 and Ano2 in mouse taste cells.","date":"2015","source":"Pflugers Archiv : European journal of physiology","url":"https://pubmed.ncbi.nlm.nih.gov/26530828","citation_count":17,"is_preprint":false},{"pmid":"39742283","id":"PMC_39742283","title":"In-depth analysis of serum antibodies against Epstein-Barr virus lifecycle proteins, and EBNA1, ANO2, GlialCAM and CRYAB peptides in patients with multiple sclerosis.","date":"2024","source":"Frontiers in immunology","url":"https://pubmed.ncbi.nlm.nih.gov/39742283","citation_count":13,"is_preprint":false},{"pmid":"30843875","id":"PMC_30843875","title":"TMEM16B determines cholecystokinin sensitivity of intestinal vagal afferents of nodose neurons.","date":"2019","source":"JCI insight","url":"https://pubmed.ncbi.nlm.nih.gov/30843875","citation_count":12,"is_preprint":false},{"pmid":"28046119","id":"PMC_28046119","title":"Permeation Mechanisms in the TMEM16B Calcium-Activated Chloride Channels.","date":"2017","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/28046119","citation_count":11,"is_preprint":false},{"pmid":"25635880","id":"PMC_25635880","title":"Assessment of the olfactory function in Italian patients with type 3 von Willebrand disease caused by a homozygous 253 Kb deletion involving VWF and TMEM16B/ANO2.","date":"2015","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/25635880","citation_count":8,"is_preprint":false},{"pmid":"38677213","id":"PMC_38677213","title":"The physiological roles of anoctamin2/TMEM16B and anoctamin1/TMEM16A in chemical senses.","date":"2024","source":"Cell calcium","url":"https://pubmed.ncbi.nlm.nih.gov/38677213","citation_count":5,"is_preprint":false},{"pmid":"39167717","id":"PMC_39167717","title":"The Ca2+-activated Cl- channel TMEM16B shapes the response time course of olfactory sensory neurons.","date":"2024","source":"The Journal of physiology","url":"https://pubmed.ncbi.nlm.nih.gov/39167717","citation_count":4,"is_preprint":false},{"pmid":"38980270","id":"PMC_38980270","title":"ANO2 Genetic Variants and Anti-VEGF Treatment Response in Neovascular AMD: A Pharmacogenetic Substudy of VIEW 1 and VIEW 2.","date":"2024","source":"Investigative ophthalmology & visual science","url":"https://pubmed.ncbi.nlm.nih.gov/38980270","citation_count":3,"is_preprint":false},{"pmid":"38825009","id":"PMC_38825009","title":"Modulation of TMEM16B channel activity by the calcium-activated chloride channel regulator 4 (CLCA4) in human cells.","date":"2024","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/38825009","citation_count":3,"is_preprint":false},{"pmid":"34917777","id":"PMC_34917777","title":"Positive modulation of the TMEM16B mediated currents by TRPV4 antagonist.","date":"2021","source":"Biochemistry and biophysics reports","url":"https://pubmed.ncbi.nlm.nih.gov/34917777","citation_count":1,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2025.10.20.683561","title":"Parkinson’s disease risk factors are expressed at brain barriers","date":"2025-10-21","source":"bioRxiv","url":"https://doi.org/10.1101/2025.10.20.683561","citation_count":0,"is_preprint":true},{"pmid":null,"id":"bio_10.1101_2024.10.11.617893","title":"Amplification of olfactory transduction currents implements sparse stimulus encoding","date":"2024-10-12","source":"bioRxiv","url":"https://doi.org/10.1101/2024.10.11.617893","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":19540,"output_tokens":5986,"usd":0.074205,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":14732,"output_tokens":5498,"usd":0.105555,"stage2_stop_reason":"end_turn"},"total_usd":0.17976,"stage1_batch_id":"msgbatch_0179Z2pxRYBsXi2xADneafRw","stage2_batch_id":"msgbatch_01LaY9ZaVdgjWArcZo9eqQE5","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n \"discoveries\": [\n {\n \"year\": 2009,\n \"finding\": \"ANO2/TMEM16B forms a calcium-activated chloride channel (CaCC) when expressed in HEK-293 cells, exhibiting channel properties closely resembling the native olfactory CaCC. The protein was identified in a proteomic screen of cilial membrane proteins of mouse olfactory sensory neurons (OSNs), and ANO2::EGFP fusion protein localized to OSN cilia in vivo.\",\n \"method\": \"Proteomic screen, adenoviral-mediated in vivo expression with fluorescence imaging, whole-cell patch-clamp electrophysiology in HEK-293 cells\",\n \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n \"confidence\": \"High\",\n \"confidence_rationale\": \"Tier 1–2 / Strong — direct patch-clamp functional assay combined with in vivo localization and proteomic identification; foundational paper replicated by multiple subsequent studies\",\n \"pmids\": [\"19561302\"],\n \"is_preprint\": false\n },\n {\n \"year\": 2009,\n \"finding\": \"TMEM16B (ANO2) confers Ca2+-dependent chloride currents when overexpressed in mammalian cells. In mouse retina, TMEM16B localizes to photoreceptor synaptic terminals and co-localizes with presynaptic adaptor proteins PSD95, VELI3, and MPP4 at ribbon synapses via a PDZ class I binding motif. TMEM16B is lost from photoreceptor membranes in MPP4-deficient mice, indicating MPP4-dependent recruitment to specialized plasma membrane domains.\",\n \"method\": \"Halide-sensitive fluorescent protein assay, whole-cell patch-clamp, immunohistochemistry, co-localization, MPP4 knockout mouse analysis\",\n \"journal\": \"The Journal of neuroscience : the official journal of the Society for Neuroscience\",\n \"confidence\": \"High\",\n \"confidence_rationale\": \"Tier 1–2 / Strong — functional electrophysiology combined with in vivo localization and genetic knockout evidence for complex membership\",\n \"pmids\": [\"19474308\"],\n \"is_preprint\": false\n },\n {\n \"year\": 2009,\n \"finding\": \"Mouse TMEM16B expressed in HEK 293T cells is directly gated by intracellular Ca2+, as demonstrated in inside-out excised patches where controlled Ca2+ concentrations rapidly activated the channel. Ca2+ concentration for half-maximal activation decreased from 4.9 µM at -50 mV to 3.3 µM at +50 mV with Hill coefficient >2, indicating cooperative Ca2+ binding. The channel is anion-selective and blocked by niflumic acid.\",\n \"method\": \"Whole-cell and inside-out patch-clamp electrophysiology in HEK 293T cells, caged Ca2+ photolysis, G-protein-coupled receptor Ca2+ release\",\n \"journal\": \"Pflugers Archiv : European journal of physiology\",\n \"confidence\": \"High\",\n \"confidence_rationale\": \"Tier 1 / Strong — rigorous in vitro reconstitution with direct Ca2+ application in excised patches and multiple activation modalities\",\n \"pmids\": [\"19475416\"],\n \"is_preprint\": false\n },\n {\n \"year\": 2010,\n \"finding\": \"Endogenous Tmem16b protein is specifically and highly expressed in the cilia of olfactory sensory neurons (OSNs) in the olfactory epithelium, as established by proteome analysis of the olfactory epithelium membrane fraction and confirmed by additional localization studies. Expression is specific to OSNs, in contrast to the broad expression of Tmem16a.\",\n \"method\": \"Membrane proteome analysis, immunohistochemistry/localization in native olfactory epithelium\",\n \"journal\": \"Chemical senses\",\n \"confidence\": \"Medium\",\n \"confidence_rationale\": \"Tier 2–3 / Strong — native tissue proteomics combined with localization, replicated across multiple labs\",\n \"pmids\": [\"20100788\"],\n \"is_preprint\": false\n },\n {\n \"year\": 2010,\n \"finding\": \"TMEM16B/ANO2 expressed in HEK 293T cells displays electrophysiological properties (anion selectivity, blocker sensitivity, Ca2+-activated kinetics) closely matching the native Ca2+-activated Cl- current in isolated mouse olfactory sensory neurons, including dynamic ion selectivity measured by rapid Ca2+ concentration jumps. TMEM16B/ANO2 co-localizes with adenylyl cyclase III at the olfactory epithelium surface, placing it in the olfactory transduction compartment.\",\n \"method\": \"Whole-cell voltage-clamp with caged Ca2+ photolysis, extracellular blocker application, ion substitution, immunohistochemistry\",\n \"journal\": \"The Journal of physiology\",\n \"confidence\": \"High\",\n \"confidence_rationale\": \"Tier 1–2 / Strong — direct comparison of heterologous and native channels with multiple orthogonal electrophysiological and pharmacological methods\",\n \"pmids\": [\"20837642\"],\n \"is_preprint\": false\n },\n {\n \"year\": 2012,\n \"finding\": \"Glutamate residues E367 and 386EEEEE390 in the first putative intracellular loop of TMEM16B play an important role in voltage dependence of the channel; mutations at these sites shift the conductance-voltage relationship toward more positive voltages without greatly affecting Ca2+ affinity.\",\n \"method\": \"Site-directed mutagenesis, whole-cell voltage-clamp in HEK 293T cells at various intracellular Ca2+ concentrations\",\n \"journal\": \"The Journal of general physiology\",\n \"confidence\": \"High\",\n \"confidence_rationale\": \"Tier 1 / Moderate — rigorous site-directed mutagenesis with functional electrophysiology; single lab but multiple mutants tested with clear structure-function conclusions\",\n \"pmids\": [\"22412191\"],\n \"is_preprint\": false\n },\n {\n \"year\": 2013,\n \"finding\": \"Using TMEM16A/TMEM16B chimeric channels, the third intracellular loop of TMEM16B (equivalent region in TMEM16A) was identified as the site controlling Ca2+ sensitivity, while the C-terminal region including TMD7-8 controls the rate of channel opening and closing. Deletion of the TMEM16A C-terminus (77 aa) accelerated kinetics, confirming the C-terminal role.\",\n \"method\": \"Chimeric protein construction, whole-cell patch-clamp in transfected mammalian cells, C-terminal deletion mutagenesis\",\n \"journal\": \"The Biochemical journal\",\n \"confidence\": \"High\",\n \"confidence_rationale\": \"Tier 1 / Moderate — systematic chimera and deletion approach with functional readout; single lab with multiple orthogonal constructs\",\n \"pmids\": [\"23570556\"],\n \"is_preprint\": false\n },\n {\n \"year\": 2013,\n \"finding\": \"TMEM16B localizes specifically to the cilia of mature olfactory sensory neurons throughout development (from E14.5 onward), consistent with a role in olfactory signal transduction during and after development.\",\n \"method\": \"Immunohistochemistry on mouse olfactory epithelium at multiple prenatal and postnatal stages\",\n \"journal\": \"Developmental neurobiology\",\n \"confidence\": \"Medium\",\n \"confidence_rationale\": \"Tier 3 / Moderate — localization-only study in native tissue, replicated across multiple developmental stages, consistent with other localization studies\",\n \"pmids\": [\"24318978\"],\n \"is_preprint\": false\n },\n {\n \"year\": 2014,\n \"finding\": \"TMEM16B gating is modulated by permeant anions: anions more permeant than Cl- slow both activation and deactivation kinetics, while less permeant anions accelerate them. Extracellular or intracellular SCN- shifts the voltage dependence of activation to more negative potentials and increases apparent Ca2+ affinity. This provides evidence that ion permeation and gating are coupled processes in TMEM16B.\",\n \"method\": \"Whole-cell and inside-out patch-clamp with systematic anion substitution, dose-response Ca2+ analysis in HEK 293T cells\",\n \"journal\": \"The Journal of general physiology\",\n \"confidence\": \"High\",\n \"confidence_rationale\": \"Tier 1 / Moderate — rigorous electrophysiology with systematic ion substitution experiments; single lab, multiple orthogonal approaches\",\n \"pmids\": [\"24863931\"],\n \"is_preprint\": false\n },\n {\n \"year\": 2015,\n \"finding\": \"TMEM16A and TMEM16B display intrinsic dual (fast and slow) gating modes regulated by voltage and extracellular chloride. Mutating residues 480RSQ482 to AVK in the first intracellular loop of TMEM16B nearly abolished slow gating, identifying this loop as a determinant of the slow gating mode.\",\n \"method\": \"Whole-cell and inside-out patch-clamp with long depolarizing pulses, site-directed mutagenesis, recordings from parotid acinar cells\",\n \"journal\": \"The Journal of physiology\",\n \"confidence\": \"High\",\n \"confidence_rationale\": \"Tier 1 / Moderate — mutagenesis combined with functional electrophysiology in both heterologous and native cell systems\",\n \"pmids\": [\"26728431\"],\n \"is_preprint\": false\n },\n {\n \"year\": 2015,\n \"finding\": \"Extracellular anthracene-9-carboxylic acid (A9C) causes voltage-dependent block of outward currents through TMEM16B and, at low Ca2+ (1.5 µM), potentiates tail currents and prolongs deactivation kinetics. The non-charged analogue A9M produces only small voltage-independent block without potentiation, demonstrating that the negative charge of A9C is required for both voltage-dependent block and potentiation.\",\n \"method\": \"Whole-cell patch-clamp pharmacology in HEK 293T cells at multiple Ca2+ concentrations and voltages\",\n \"journal\": \"Biochimica et biophysica acta\",\n \"confidence\": \"Medium\",\n \"confidence_rationale\": \"Tier 1–2 / Weak — rigorous electrophysiology with charge-matched analogue control; single lab, single method\",\n \"pmids\": [\"25620774\"],\n \"is_preprint\": false\n },\n {\n \"year\": 2016,\n \"finding\": \"TMEM16B KO mice show abolition of Ca2+-activated Cl- currents in olfactory sensory neurons, increased action potential firing (prolonged responses with more APs) upon odorant stimulation, reduced basal spiking in I7-expressing neurons, and supernumerary I7 glomeruli in the olfactory bulb, demonstrating that TMEM16B controls AP firing pattern and correct axonal targeting of OSNs.\",\n \"method\": \"TMEM16B knockout mouse, suction electrode and loose-patch recordings from isolated OSNs and olfactory epithelium slices, behavioral olfactory testing, glomerular mapping\",\n \"journal\": \"The Journal of general physiology\",\n \"confidence\": \"High\",\n \"confidence_rationale\": \"Tier 2 / Strong — genetic KO with multiple electrophysiological recording modalities, behavioral readout, and anatomical analysis\",\n \"pmids\": [\"27619419\"],\n \"is_preprint\": false\n },\n {\n \"year\": 2016,\n \"finding\": \"ANO2/TMEM16B is expressed in the basolateral membrane of the retinal pigment epithelium (RPE), and siRNA knockdown of ANO2 reduces both Ca2+-dependent chloride conductance and ANO2 protein expression in primary mouse RPE cells and ARPE-19 cells, establishing ANO2 as a contributor to the Ca2+-activated Cl- channel current in RPE.\",\n \"method\": \"Confocal immunohistochemistry on retinal sections, siRNA knockdown, whole-cell patch-clamp, Western blot, PCR\",\n \"journal\": \"Experimental eye research\",\n \"confidence\": \"Medium\",\n \"confidence_rationale\": \"Tier 2 / Moderate — siRNA knockdown with direct electrophysiological readout and protein quantification; single lab, multiple orthogonal methods\",\n \"pmids\": [\"27940219\"],\n \"is_preprint\": false\n },\n {\n \"year\": 2017,\n \"finding\": \"PIP2 inhibits TMEM16B channel activity (~0.2-fold) while activating TMEM16A. PIP2 modulation of TMEM16B does not vary over broad Ca2+ ranges but is only detectable at highly depolarized potentials. A voltage-sensitive phosphatase (DrVSP) that degrades PIP2 enhanced TMEM16B currents; this effect was abolished by an inactivating DrVSP mutation or counteracted by PI(4)P 5-kinase co-expression. Modulation is due to changes in channel gating, not single-channel conductance.\",\n \"method\": \"Whole-cell patch-clamp with soluble PIP2 analogue (diC8-PIP2), DrVSP co-expression, PI(4)P 5-kinase co-expression, inactivating DrVSP mutant control\",\n \"journal\": \"British journal of pharmacology\",\n \"confidence\": \"High\",\n \"confidence_rationale\": \"Tier 1–2 / Moderate — multiple genetic and pharmacological tools for PIP2 manipulation with functional electrophysiology; single lab, orthogonal approaches\",\n \"pmids\": [\"28616863\"],\n \"is_preprint\": false\n },\n {\n \"year\": 2017,\n \"finding\": \"In inferior olivary (IO) neurons, Ca2+ influx through dendritic high-threshold voltage-gated Ca2+ channels activates TMEM16B-mediated CaCCs, which contribute to membrane repolarization. Loss of TMEM16B in knockout mice abolishes CaCCs in IO neurons, leading to markedly diminished AP firing of IO neurons and severe cerebellar motor learning deficits.\",\n \"method\": \"TMEM16B knockout mouse, whole-cell patch-clamp in IO neurons, behavioral cerebellar motor learning tests\",\n \"journal\": \"Neuron\",\n \"confidence\": \"High\",\n \"confidence_rationale\": \"Tier 2 / Strong — genetic KO with direct electrophysiology in native neurons and behavioral phenotyping; single lab but multiple orthogonal approaches\",\n \"pmids\": [\"28858616\"],\n \"is_preprint\": false\n },\n {\n \"year\": 2017,\n \"finding\": \"Residues R573 and K540 at the entrance and inside the putative pore of TMEM16B control ion permeability in a side-of-membrane and activation-level dependent manner. R573 mutation abolishes the anomalous mole fraction effect observed with permeant anions and alters apparent Ca2+ sensitivity, indicating that pore-facing residues control both ion selectivity and gating.\",\n \"method\": \"Site-directed mutagenesis of R573 and K540, whole-cell and inside-out patch-clamp in HEK-293 cells\",\n \"journal\": \"PloS one\",\n \"confidence\": \"Medium\",\n \"confidence_rationale\": \"Tier 1 / Weak — rigorous mutagenesis with functional electrophysiology but single lab, single paper\",\n \"pmids\": [\"28046119\"],\n \"is_preprint\": false\n },\n {\n \"year\": 2017,\n \"finding\": \"TMEM16A and TMEM16B can form heteromeric channels in addition to homomeric channels in pinealocytes. Co-expression of both subunits or a tandem TMEM16A-TMEM16B construct in HEK293 cells recapitulates the electrophysiological characteristics of native pineal CaCCs. Both channels contribute to ClCa currents in pinealocytes, which regulate melatonin secretion.\",\n \"method\": \"Bimolecular fluorescence complementation (BiFC), FRET, co-immunoprecipitation, tandem channel expression in HEK293, siRNA knockdown, whole-cell patch-clamp, melatonin secretion assay\",\n \"journal\": \"The Journal of biological chemistry\",\n \"confidence\": \"High\",\n \"confidence_rationale\": \"Tier 1–2 / Moderate — three orthogonal methods for heteromeric complex (BiFC, FRET, co-IP) plus functional reconstitution; single lab\",\n \"pmids\": [\"29187602\"],\n \"is_preprint\": false\n },\n {\n \"year\": 2019,\n \"finding\": \"TMEM16B (ANO2) is the dominant Ca2+-activated Cl- channel subunit in intestinal vagal afferents of nodose neurons and is required for cholecystokinin (CCK)-induced satiety. Heterozygous TMEM16B KO reduces CCK-induced current, CCK-induced satiety, and energy expenditure, producing an obese phenotype. TMEM16B expression is reduced in nodose neurons of obese high-fat diet mice.\",\n \"method\": \"Whole-cell patch-clamp in nodose neurons, TMEM16B heterozygous KO mouse, behavioral feeding/satiety assays, metabolic measurements, high-fat diet model\",\n \"journal\": \"JCI insight\",\n \"confidence\": \"High\",\n \"confidence_rationale\": \"Tier 2 / Moderate — genetic KO with direct electrophysiology in native neurons and multiple behavioral/metabolic readouts; single lab\",\n \"pmids\": [\"30843875\"],\n \"is_preprint\": false\n },\n {\n \"year\": 2019,\n \"finding\": \"TMEM16B in lateral septum (LS) neurons regulates spike frequency and spike frequency adaptation. Loss of TMEM16B alters neurotransmitter release at the hippocampal-LS synapse and leads to lengthened aggressive behavior in male mice during resident-intruder testing.\",\n \"method\": \"Whole-cell patch-clamp in LS neurons, TMEM16B KO mouse, resident-intruder behavioral paradigm\",\n \"journal\": \"The Journal of neuroscience : the official journal of the Society for Neuroscience\",\n \"confidence\": \"High\",\n \"confidence_rationale\": \"Tier 2 / Moderate — genetic KO with direct electrophysiology in native neurons and behavioral quantification; single lab, two orthogonal approaches\",\n \"pmids\": [\"31320449\"],\n \"is_preprint\": false\n },\n {\n \"year\": 2021,\n \"finding\": \"The TRPV4 antagonist GSK2193874 enhances chloride currents mediated by TMEM16B expressed in HEK cells at nanomolar concentrations, and the TRPV4 agonist GSK1016790A enhances native CaCCs in Xenopus oocytes, identifying these compounds as positive modulators of TMEM16B-mediated currents.\",\n \"method\": \"Whole-cell patch-clamp in HEK cells expressing TMEM16B, native CaCC recordings in Xenopus oocytes\",\n \"journal\": \"Biochemistry and biophysics reports\",\n \"confidence\": \"Medium\",\n \"confidence_rationale\": \"Tier 2 / Weak — direct electrophysiology in heterologous and native systems; single lab, single paper\",\n \"pmids\": [\"34917777\"],\n \"is_preprint\": false\n },\n {\n \"year\": 2024,\n \"finding\": \"CLCA4 (Ca2+-activated Cl- channel regulator 4) potentiates TMEM16B channel activity. The N-terminal portion of CLCA4 (N-CLCA4) after self-cleavage is secreted and its von Willebrand factor type A (VWA) domain is sufficient to increase ICaCC carried by TMEM16B in HEK293T cells. This interaction is mediated by the metal ion-dependent adhesion site (MIDAS) motif within VWA, defining a specific CLCA4-TMEM16B regulatory pair distinct from the CLCA1-TMEM16A pair.\",\n \"method\": \"Overexpression in HEK293T cells, domain deletion constructs, MIDAS motif mutagenesis, whole-cell patch-clamp\",\n \"journal\": \"The Journal of biological chemistry\",\n \"confidence\": \"Medium\",\n \"confidence_rationale\": \"Tier 2 / Moderate — functional electrophysiology with domain mapping and motif mutagenesis; single lab but multiple constructs\",\n \"pmids\": [\"38825009\"],\n \"is_preprint\": false\n },\n {\n \"year\": 2024,\n \"finding\": \"In TMEM16B knockout OSNs, while basic membrane properties (input resistance, resting potential, voltage-gated currents) are unchanged, TMEM16B determines the time required for the odorant response to reach its peak and to terminate after stimulation. Absence of TMEM16B causes faster response termination, allowing KO OSNs to fire action potentials more reliably during rapid repeated stimulation. The CNG channel predominantly controls response delay and adaptation, while TMEM16B controls response kinetics and amplitude amplification.\",\n \"method\": \"TMEM16B knockout mouse, suction electrode and whole-cell patch-clamp recordings from isolated OSNs and epithelial slices, odorant stimulation protocols\",\n \"journal\": \"The Journal of physiology\",\n \"confidence\": \"High\",\n \"confidence_rationale\": \"Tier 2 / Moderate — genetic KO with multiple electrophysiological recording configurations in native neurons; single lab but orthogonal approaches\",\n \"pmids\": [\"39167717\"],\n \"is_preprint\": false\n },\n {\n \"year\": 2024,\n \"finding\": \"In TMEM16B knockout mice, olfactory sensory representations are denser and OSN response magnitudes are increased (measured by multiphoton microscopy), and animals show increased aversion to trimethylamine and decreased efficiency in olfactory-guided navigation, indicating TMEM16B sparsens peripheral olfactory sensory representations.\",\n \"method\": \"TMEM16B knockout mouse, multiphoton microscopy of OSN activity in olfactory epithelium, behavioral olfactory-guided navigation and odor aversion assays\",\n \"journal\": \"bioRxiv\",\n \"confidence\": \"Medium\",\n \"confidence_rationale\": \"Tier 2 / Weak — genetic KO with in vivo imaging and behavioral readouts; preprint, single lab\",\n \"pmids\": [],\n \"is_preprint\": true\n }\n ],\n \"current_model\": \"ANO2/TMEM16B is a calcium-activated chloride channel (CaCC) that localizes to the cilia of olfactory sensory neurons, photoreceptor synaptic terminals, retinal pigment epithelium, inferior olivary neurons, lateral septal neurons, and intestinal vagal afferents, where it amplifies odorant-evoked currents and shapes action potential firing kinetics; its gating is cooperatively regulated by intracellular Ca2+ (EC50 ~3–5 µM) and membrane voltage, with permeant anions coupling gating to permeation, and key structural determinants identified include the third intracellular loop (Ca2+ sensitivity), C-terminal/TMD7-8 region (kinetics), first intracellular loop residues (voltage dependence and slow gating), and pore residues R573/K540 (ion selectivity); the channel is inhibited by PIP2 depletion, potentiated by CLCA4, and can form heteromeric complexes with TMEM16A.\"\n}\n```","stage2_raw":"{\n \"mechanistic_narrative\": \"ANO2/TMEM16B is a calcium-activated chloride channel (CaCC) that shapes neuronal signaling kinetics across multiple sensory and neural circuits [#0, #11]. It was identified in the ciliary membrane of olfactory sensory neurons, where it generates a current closely matching the native olfactory CaCC and amplifies odorant-evoked responses [#0, #4]; in knockout mice it controls the kinetics and amplitude of the odorant response, governing action potential firing patterns, response termination, and correct axonal targeting of OSNs to olfactory bulb glomeruli [#11, #21]. The channel is directly gated by intracellular Ca2+ in a cooperative, voltage-dependent manner (half-maximal activation ~3–5 µM) and is anion-selective [#2]. Structure–function studies localize Ca2+ sensitivity to the third intracellular loop, gating kinetics to the C-terminal/TMD7-8 region, voltage dependence and slow gating to first intracellular loop residues, and ion selectivity to pore residues R573/K540, with permeant anions coupling gating to permeation [#5, #6, #8, #9, #15]. ANO2 activity is inhibited by PIP2 and potentiated by the secreted VWA domain of CLCA4 acting through its MIDAS motif [#13, #20], and ANO2 forms both homomeric and heteromeric channels with TMEM16A [#16]. Beyond olfaction, ANO2 supplies CaCC currents that shape firing and circuit output in photoreceptor ribbon synapses, retinal pigment epithelium, inferior olivary neurons, lateral septal neurons, and intestinal vagal afferents, where its loss produces deficits in cerebellar motor learning, aggression behavior, and CCK-induced satiety [#1, #12, #14, #17, #18].\",\n \"teleology\": [\n {\n \"year\": 2009,\n \"claim\": \"Establishing the molecular identity of the long-sought native olfactory calcium-activated chloride channel, the question was which gene product carries this current; ANO2/TMEM16B was identified as a CaCC residing in OSN cilia.\",\n \"evidence\": \"Ciliary membrane proteomics, in vivo EGFP-fusion localization, and whole-cell patch-clamp in HEK-293 cells\",\n \"pmids\": [\"19561302\"],\n \"confidence\": \"High\",\n \"gaps\": [\"Single-channel and structural basis of gating not resolved\", \"Physiological necessity in vivo not yet tested by knockout\"]\n },\n {\n \"year\": 2009,\n \"claim\": \"To define how ANO2 is targeted to functional sites beyond cilia, its retinal localization and recruitment mechanism were examined, placing it at photoreceptor ribbon synapses via a PDZ-dependent scaffold.\",\n \"evidence\": \"Halide-sensitive fluorescent assay, patch-clamp, immunohistochemistry, co-localization with PSD95/VELI3/MPP4, and MPP4 knockout mouse\",\n \"pmids\": [\"19474308\"],\n \"confidence\": \"High\",\n \"gaps\": [\"Functional role of ANO2 in synaptic transmission not directly measured\", \"PDZ partner directly binding ANO2 not biochemically isolated\"]\n },\n {\n \"year\": 2009,\n \"claim\": \"To distinguish direct Ca2+ gating from indirect activation, ANO2 was tested in excised patches with controlled Ca2+, demonstrating direct cooperative Ca2+ activation with mild voltage dependence.\",\n \"evidence\": \"Inside-out and whole-cell patch-clamp with caged Ca2+ photolysis in HEK 293T cells\",\n \"pmids\": [\"19475416\"],\n \"confidence\": \"High\",\n \"gaps\": [\"Structural Ca2+-binding site not identified\", \"Mechanism of cooperativity unresolved\"]\n },\n {\n \"year\": 2010,\n \"claim\": \"To confirm ANO2 is the native olfactory CaCC rather than a mimic, heterologous and native currents were directly compared and ANO2 was placed in the transduction compartment alongside adenylyl cyclase III.\",\n \"evidence\": \"Native OSN proteomics, immunohistochemistry, and voltage-clamp with rapid Ca2+ jumps comparing heterologous and native channels\",\n \"pmids\": [\"20100788\", \"20837642\"],\n \"confidence\": \"High\",\n \"gaps\": [\"Quantitative contribution to odor signal amplification not yet established in vivo\"]\n },\n {\n \"year\": 2012,\n \"claim\": \"To map the channel's voltage sensitivity, acidic residues in the first intracellular loop were mutated, identifying E367 and 386EEEEE390 as determinants of voltage dependence separable from Ca2+ affinity.\",\n \"evidence\": \"Site-directed mutagenesis and whole-cell voltage-clamp across Ca2+ concentrations in HEK 293T cells\",\n \"pmids\": [\"22412191\"],\n \"confidence\": \"High\",\n \"gaps\": [\"Whether these residues form a voltage sensor or modulate Ca2+-coupled gating not distinguished\"]\n },\n {\n \"year\": 2013,\n \"claim\": \"To dissect which domains govern Ca2+ sensitivity versus kinetics, TMEM16A/B chimeras and deletions localized Ca2+ sensitivity to the third intracellular loop and gating kinetics to the C-terminal/TMD7-8 region.\",\n \"evidence\": \"Chimeric construct and C-terminal deletion analysis with whole-cell patch-clamp\",\n \"pmids\": [\"23570556\"],\n \"confidence\": \"High\",\n \"gaps\": [\"Atomic-resolution structure of these regions in ANO2 absent\"]\n },\n {\n \"year\": 2014,\n \"claim\": \"To probe whether permeation and gating are coupled, systematic anion substitution showed permeant anions tune activation/deactivation kinetics and apparent Ca2+ affinity, establishing permeation-gating coupling.\",\n \"evidence\": \"Whole-cell and inside-out patch-clamp with anion substitution and Ca2+ dose-response in HEK 293T cells\",\n \"pmids\": [\"24863931\"],\n \"confidence\": \"High\",\n \"gaps\": [\"Pore residues mediating anion-gating coupling not yet pinpointed in this study\"]\n },\n {\n \"year\": 2015,\n \"claim\": \"To resolve the determinants of distinct gating modes, dual fast/slow gating was characterized and 480RSQ482 in the first intracellular loop identified as required for slow gating.\",\n \"evidence\": \"Patch-clamp with long depolarizing pulses, mutagenesis, and recordings from parotid acinar cells\",\n \"pmids\": [\"26728431\"],\n \"confidence\": \"High\",\n \"gaps\": [\"Physiological significance of slow gating mode in native neurons unclear\"]\n },\n {\n \"year\": 2015,\n \"claim\": \"To define a charged pharmacological probe of gating, A9C was shown to produce charge-dependent voltage-dependent block and potentiation, using the uncharged A9M analogue as control.\",\n \"evidence\": \"Whole-cell patch-clamp pharmacology at multiple Ca2+ and voltage conditions in HEK 293T cells\",\n \"pmids\": [\"25620774\"],\n \"confidence\": \"Medium\",\n \"gaps\": [\"Binding site of A9C not mapped\", \"Single lab, single method\"]\n },\n {\n \"year\": 2016,\n \"claim\": \"To establish in vivo function in olfaction, TMEM16B knockout mice were used to show loss of OSN CaCCs alters AP firing patterns, basal spiking, and glomerular axon targeting.\",\n \"evidence\": \"Knockout mouse with suction/loose-patch recordings, behavioral testing, and glomerular mapping\",\n \"pmids\": [\"27619419\"],\n \"confidence\": \"High\",\n \"gaps\": [\"Mechanism linking channel activity to axon guidance not defined\"]\n },\n {\n \"year\": 2016,\n \"claim\": \"To extend ANO2's role beyond neurons, it was shown to contribute Ca2+-activated Cl- conductance in retinal pigment epithelium via siRNA knockdown.\",\n \"evidence\": \"Immunohistochemistry, siRNA knockdown, patch-clamp, and Western blot in primary and ARPE-19 cells\",\n \"pmids\": [\"27940219\"],\n \"confidence\": \"Medium\",\n \"gaps\": [\"Physiological RPE function of ANO2 current not established\", \"Knockdown partial\"]\n },\n {\n \"year\": 2017,\n \"claim\": \"To identify lipid regulation, PIP2 was shown to inhibit ANO2 (opposite to TMEM16A) through gating changes, using a voltage-sensitive phosphatase and kinase manipulation.\",\n \"evidence\": \"Whole-cell patch-clamp with diC8-PIP2, DrVSP co-expression with inactivating control, and PI(4)P 5-kinase\",\n \"pmids\": [\"28616863\"],\n \"confidence\": \"High\",\n \"gaps\": [\"PIP2 interaction site on ANO2 not mapped\", \"Effect only detectable at depolarized potentials\"]\n },\n {\n \"year\": 2017,\n \"claim\": \"To extend ANO2's circuit role, knockout studies showed it carries dendritic CaCCs in inferior olivary neurons that drive repolarization, firing, and cerebellar motor learning.\",\n \"evidence\": \"Knockout mouse with patch-clamp in IO neurons and behavioral motor learning tests\",\n \"pmids\": [\"28858616\"],\n \"confidence\": \"High\",\n \"gaps\": [\"Coupling between specific voltage-gated Ca2+ channels and ANO2 not molecularly defined\"]\n },\n {\n \"year\": 2017,\n \"claim\": \"To localize pore selectivity determinants, mutagenesis of R573 and K540 showed these residues control ion permeability, the anomalous mole fraction effect, and apparent Ca2+ sensitivity.\",\n \"evidence\": \"Site-directed mutagenesis with whole-cell and inside-out patch-clamp in HEK-293 cells\",\n \"pmids\": [\"28046119\"],\n \"confidence\": \"Medium\",\n \"gaps\": [\"Structural model of pore geometry absent\", \"Single lab, single paper\"]\n },\n {\n \"year\": 2017,\n \"claim\": \"To test subunit assembly, ANO2 was shown to form heteromeric channels with TMEM16A in pinealocytes, contributing to melatonin-regulating CaCC currents.\",\n \"evidence\": \"BiFC, FRET, co-immunoprecipitation, tandem construct expression, siRNA, patch-clamp, and melatonin secretion assay\",\n \"pmids\": [\"29187602\"],\n \"confidence\": \"High\",\n \"gaps\": [\"Stoichiometry and physiological prevalence of heteromers in other tissues unknown\"]\n },\n {\n \"year\": 2019,\n \"claim\": \"To uncover a metabolic role, ANO2 was identified as the dominant CaCC in vagal nodose afferents required for CCK-induced satiety, with heterozygous loss producing obesity.\",\n \"evidence\": \"Patch-clamp in nodose neurons, heterozygous knockout mouse, feeding/satiety and metabolic assays, high-fat diet model\",\n \"pmids\": [\"30843875\"],\n \"confidence\": \"High\",\n \"gaps\": [\"Signaling link between CCK receptor activation and ANO2 not fully resolved\"]\n },\n {\n \"year\": 2019,\n \"claim\": \"To assess central circuit function, ANO2 in lateral septum neurons was shown to regulate spike frequency adaptation and synaptic neurotransmitter release, with loss prolonging aggressive behavior.\",\n \"evidence\": \"Patch-clamp in LS neurons, knockout mouse, and resident-intruder behavioral paradigm\",\n \"pmids\": [\"31320449\"],\n \"confidence\": \"High\",\n \"gaps\": [\"Mechanism of presynaptic modulation unresolved\"]\n },\n {\n \"year\": 2021,\n \"claim\": \"To find positive pharmacological modulators, TRPV4 ligands GSK2193874 and GSK1016790A were shown to enhance ANO2-mediated and native CaCC currents.\",\n \"evidence\": \"Patch-clamp in HEK cells and native CaCC recordings in Xenopus oocytes\",\n \"pmids\": [\"34917777\"],\n \"confidence\": \"Medium\",\n \"gaps\": [\"Binding site and selectivity over TRPV4 not established\", \"Single lab, single paper\"]\n },\n {\n \"year\": 2024,\n \"claim\": \"To identify a protein regulator, CLCA4 was shown to potentiate ANO2 via its secreted self-cleaved VWA domain acting through the MIDAS motif, defining a CLCA4-ANO2 pair.\",\n \"evidence\": \"Overexpression with domain deletion and MIDAS mutagenesis and whole-cell patch-clamp in HEK293T cells\",\n \"pmids\": [\"38825009\"],\n \"confidence\": \"Medium\",\n \"gaps\": [\"Endogenous CLCA4-ANO2 interaction in native tissue not shown\", \"Structural basis of potentiation unknown\"]\n },\n {\n \"year\": 2024,\n \"claim\": \"To refine ANO2's role in olfactory coding, knockout studies separated its function (response kinetics and amplitude) from CNG channel function (delay and adaptation), showing ANO2 sparsens sensory representations.\",\n \"evidence\": \"Knockout mouse with suction/whole-cell recordings and multiphoton in vivo imaging plus behavioral navigation/aversion assays (one preprint)\",\n \"pmids\": [\"39167717\"],\n \"confidence\": \"High\",\n \"gaps\": [\"In vivo imaging behavioral findings partly in preprint form\", \"Circuit-level consequences of denser representations not fully characterized\"]\n },\n {\n \"year\": null,\n \"claim\": \"An atomic structure of ANO2 defining the Ca2+-binding pocket, anion pore, voltage-coupling elements, and the molecular basis of its lipid and CLCA4 regulation remains to be determined.\",\n \"evidence\": \"\",\n \"pmids\": [],\n \"confidence\": \"High\",\n \"gaps\": [\"No experimentally determined ANO2 structure in the corpus\", \"Direct PIP2 and CLCA4 binding sites unmapped\", \"Heteromer stoichiometry in native tissues unknown\"]\n }\n ],\n \"mechanism_profile\": {\n \"molecular_activity\": [\n {\"term_id\": \"GO:0005215\", \"supporting_discovery_ids\": [0, 2, 4]},\n {\"term_id\": \"GO:0140299\", \"supporting_discovery_ids\": [2, 5, 8]},\n {\"term_id\": \"GO:0005216\", \"supporting_discovery_ids\": [0]}\n ],\n \"localization\": [\n {\"term_id\": \"GO:0005929\", \"supporting_discovery_ids\": [0, 3, 7]},\n {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [1, 12]}\n ],\n \"pathway\": [\n {\"term_id\": \"R-HSA-112316\", \"supporting_discovery_ids\": [11, 14, 18, 21]},\n {\"term_id\": \"R-HSA-9709957\", \"supporting_discovery_ids\": [0, 21, 22]},\n {\"term_id\": \"R-HSA-382551\", \"supporting_discovery_ids\": [2, 8]}\n ],\n \"complexes\": [\n \"TMEM16A-TMEM16B heteromeric channel\"\n ],\n \"partners\": [\n \"TMEM16A\",\n \"CLCA4\",\n \"MPP4\",\n \"PSD95\",\n \"VELI3\"\n ],\n \"other_free_text\": []\n }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":6,"faith_pct":100.0}}