{"gene":"KCNK9","run_date":"2026-04-28T18:30:27","timeline":{"discoveries":[{"year":2000,"finding":"TASK-3 (KCNK9) encodes a time-independent, noninactivating K+-selective background channel with a single-channel conductance of 27 pS at -60 mV; extracellular pH sensitivity is conferred by histidine at position 98, as H98D mutation abolishes pH sensitivity; the channel is blocked by barium, quinidine, and lidocaine.","method":"Heterologous expression in COS-7 cells, whole-cell and single-channel patch-clamp, site-directed mutagenesis","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — in vitro electrophysiology with mutagenesis, replicated in two independent labs (PMID:10734076 and PMID:10747866)","pmids":["10734076","10747866"],"is_preprint":false},{"year":2000,"finding":"Histidine 98 in the extracellular pore region of TASK-3 acts as the pH sensor; substitution with asparagine or tyrosine abolishes pH sensitivity, and the residue is located at the outer pore adjacent to the selectivity filter.","method":"Xenopus oocyte expression, two-electrode voltage clamp, site-directed mutagenesis","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — mutagenesis with functional validation, replicated across two independent studies","pmids":["10747866","10734076"],"is_preprint":false},{"year":2001,"finding":"TASK-1 and TASK-3 form functional heterodimers when co-expressed in Xenopus oocytes; heterodimeric channels show intermediate pH sensitivity and TASK-1-like ruthenium red insensitivity; tandem-linked TASK-3/TASK-1 construct recapitulates heterodimer properties; epitope-tagged channels localize primarily to the plasma membrane in mammalian cells.","method":"Xenopus oocyte co-expression, two-electrode voltage clamp, tandem construct expression, immunostaining in mammalian cells","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1-2 — functional heterodimer confirmed by tandem construct, pharmacological profiling, and co-immunoprecipitation in follow-up studies; replicated across multiple labs","pmids":["11733509"],"is_preprint":false},{"year":2002,"finding":"Volatile anesthetic (halothane) activation and neurotransmitter (TRH) inhibition of TASK-3 both require a six-residue sequence at the cytoplasmic C-terminus/final transmembrane domain interface (VLRFLT region); mutations in this region abolish both modalities; a large portion of the C-terminus is additionally needed for full halothane and TRH effects on TASK-3.","method":"Site-directed mutagenesis, heterologous expression, whole-cell patch-clamp in Xenopus oocytes and mammalian cells","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — systematic mutagenesis with orthogonal pharmacological and receptor-mediated readouts","pmids":["11886861"],"is_preprint":false},{"year":2002,"finding":"14-3-3 proteins interact with the conserved C-terminal pentapeptide motif (RRxSx) of TASK-3 and promote trafficking of the channel to the surface membrane; deletion of a single C-terminal amino acid abolishes 14-3-3 binding and strongly reduces macroscopic currents; TASK-1 and 14-3-3 co-immunoprecipitate from synaptic membrane extracts.","method":"Two-hybrid analysis, co-immunoprecipitation, Xenopus oocyte expression, surface expression assay, voltage-clamp, C-terminal truncation mutants","journal":"The Journal of physiology","confidence":"High","confidence_rationale":"Tier 2 — reciprocal Co-IP and functional electrophysiology with mutagenesis, replicated by subsequent studies","pmids":["12433946"],"is_preprint":false},{"year":2003,"finding":"Ruthenium red inhibits TASK-3 by simultaneously binding to glutamate 70 of both subunits; mutation E70R or E70C abolishes inhibition; in tandem-linked homodimers, mutation of Glu70 in either subunit prevents RR action; Hill coefficient of 1 indicates a single polycationic molecule bridges both subunits; the reciprocal mutation K70E in TASK-1 confers RR sensitivity.","method":"Site-directed mutagenesis of tandem-linked and monomeric constructs, Xenopus oocyte expression, two-electrode voltage-clamp, Hill analysis","journal":"Molecular pharmacology","confidence":"High","confidence_rationale":"Tier 1 — reconstituted pharmacological mechanism with mutagenesis in tandem constructs, clear mechanistic model","pmids":["12606773"],"is_preprint":false},{"year":2003,"finding":"KCNK9 is amplified (3–10-fold) in ~10% of breast tumors and overexpressed in 44%; overexpression in cell lines promotes tumor formation and confers resistance to hypoxia and serum deprivation, identifying KCNK9 as an oncogene at 8q24.3.","method":"Representational difference analysis, cell line overexpression, xenograft tumor formation assays, survival assays under hypoxia/serum deprivation","journal":"Cancer cell","confidence":"High","confidence_rationale":"Tier 2 — loss/gain-of-function in cell lines with multiple phenotypic readouts; foundational oncology paper with >200 citations","pmids":["12676587"],"is_preprint":false},{"year":2003,"finding":"Potassium channel function of TASK3 is required for its oncogenic activities; a G95E pore mutation abolishes K+ current and abrogates proliferation in low serum, resistance to apoptosis, and tumor growth in nude mice; G95E acts as a dominant-negative, suppressing wild-type TASK3 current and tumorigenicity when co-expressed.","method":"Point mutagenesis (G95E), patch-clamp electrophysiology, cell proliferation and apoptosis assays, nude mouse xenograft","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1-2 — direct causal link established by dominant-negative mutagenesis with in vitro and in vivo readouts","pmids":["12782791"],"is_preprint":false},{"year":2004,"finding":"TASK-1 and TASK-3 subunits co-immunoprecipitate from membranes of transfected mammalian cells; a dominant-negative TASK-1(Y191F) construct suppresses TASK-3 currents; heteromeric TASK-1/TASK-3 channels in hypoglossal motoneurons display pH and isoflurane sensitivities matching the heterodimer pharmacological profile.","method":"Co-immunoprecipitation, dominant-negative suppression, whole-cell patch-clamp in heterologous cells and native neurons, tandem construct expression","journal":"The Journal of neuroscience","confidence":"High","confidence_rationale":"Tier 2 — reciprocal co-IP, dominant-negative, and native neuron recordings converge on same conclusion","pmids":["15282272"],"is_preprint":false},{"year":2004,"finding":"Native 38 pS background K+ channels in cerebellar granule neurons consist of both homomeric TASK-3 and heteromeric TASK-1/TASK-3; heteromers are distinguished by their ruthenium red insensitivity and intermediate pH sensitivity in single-channel recordings from native patches.","method":"Single-channel patch-clamp in COS-7 cells and native cerebellar granule neurons, pharmacological dissection with ruthenium red and pH","journal":"The Journal of physiology","confidence":"High","confidence_rationale":"Tier 2 — comparison of cloned and native channels with pharmacological fingerprinting in native cells","pmids":["14678492"],"is_preprint":false},{"year":2004,"finding":"Zinc selectively blocks TASK-3 (IC50 ~20 µM) but not TASK-1 or TASK-2; both E70 and H98 are critical for zinc block; E70K mutation abolishes zinc sensitivity of TASK-3, while the reverse K70E mutation confers zinc sensitivity to TASK-1; TASK-3/TASK-1 concatamer channels are zinc-insensitive, consistent with heterodimer formation.","method":"Site-directed mutagenesis, two-electrode voltage-clamp in Xenopus oocytes, concatamer channel expression","journal":"The Journal of physiology","confidence":"High","confidence_rationale":"Tier 1 — mutagenesis with pharmacological validation identifying two-site zinc binding mechanism","pmids":["15284350"],"is_preprint":false},{"year":2006,"finding":"Glutamate 70 of TASK-3 mediates sensitivity to extracellular divalent cations (Ca2+, Mg2+); replacing E70 with lysine or arginine abolishes divalent cation sensitivity; the reverse mutation K70E in TASK-1 confers divalent cation sensitivity; spermine and ruthenium red act similarly via E70 to decrease TASK-3 open probability.","method":"Mutagenesis, single-channel patch-clamp in HEK293 cells, whole-cell recordings in thalamocortical neurons","journal":"The Journal of physiology","confidence":"High","confidence_rationale":"Tier 1 — bidirectional mutagenesis with single-channel and native neuron validation","pmids":["16513667"],"is_preprint":false},{"year":2006,"finding":"Depolarization-induced Ca2+ entry via L-type channels activates the calcineurin pathway to upregulate TASK-3 transcription in cerebellar granule neurons; increased TASK-3 mRNA leads to elevated protein and IKso conductance, causing membrane hyperpolarization; blocking L-type Ca2+ channels or calcineurin abrogates TASK-3 expression and induces hyperexcitability.","method":"RT-PCR, pharmacological block of L-type channels (nifedipine) and calcineurin (FK506/cyclosporin A), patch-clamp electrophysiology in primary neurons","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 — multiple pharmacological interventions linking Ca2+ entry, calcineurin, transcription, and functional channel output","pmids":["16864570"],"is_preprint":false},{"year":2007,"finding":"Protein kinase C (PKCα) phosphorylates TASK-3 at Thr341 in the C-terminus, reducing channel current; Gαq-coupled M3 muscarinic receptor activation inhibits TASK-3 through a direct action of Gαq on the channel independent of PKC; PKC activation opposes rather than transduces Gαq-mediated inhibition.","method":"Gene silencing (siRNA), mutagenesis (T341A), whole-cell patch-clamp, Gαq antagonist (YM-254890), PKC inhibitors","journal":"Molecular pharmacology","confidence":"High","confidence_rationale":"Tier 1-2 — phosphorylation site identified by mutagenesis, pathway dissected with siRNA and selective inhibitors","pmids":["17374744"],"is_preprint":false},{"year":2007,"finding":"TASK-3 (KCNK9) is maternally imprinted (paternal allele silenced); a missense mutation in the maternal copy (G236R) fully abolishes TASK-3 channel current both as a homodimer and as a heterodimer with K2P3.1, causing Birk Barel mental retardation dysmorphism syndrome.","method":"Genetic mapping, DNA sequencing, Xenopus oocyte electrophysiology of mutant channels, imprinting analysis","journal":"American journal of human genetics","confidence":"High","confidence_rationale":"Tier 2 — genetic disease mechanism linked directly to loss of channel function by electrophysiology","pmids":["18678320"],"is_preprint":false},{"year":2007,"finding":"TASK-3 KO mice show reduced sensitivity to halothane anesthetic and cannabinoid receptor agonist WIN55212-2 but unaltered responses to propofol, morphine, and lidocaine, demonstrating TASK-3's specific role in mediating select anesthetic and cannabinoid effects in vivo.","method":"Germline TASK-3 knockout mouse, pharmacological behavioral testing (halothane, cannabinoid, alpha-2 agonist, propofol, morphine, lidocaine)","journal":"The Journal of pharmacology and experimental therapeutics","confidence":"High","confidence_rationale":"Tier 2 — clean KO mouse with selective pharmacological phenotype across multiple drug classes","pmids":["17875609"],"is_preprint":false},{"year":2007,"finding":"The M1P1 extracellular loop of TASK-3 apposes the selectivity filter; disulfide bridge formation between E70C in M1P1 and H98C in the pore confirmed proximity; M1P1 loop swap between TASK-1 and TASK-3 transfers pH sensitivity, demonstrating the loop regulates channel gating.","method":"Cysteine cross-linking with cadmium, dithiothreitol, M1P1 loop chimeras, mutagenesis, voltage-clamp in HEK cells","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — covalent cross-linking and chimera experiments establish structural proximity and functional role","pmids":["18417474"],"is_preprint":false},{"year":2007,"finding":"A di-acidic EDE motif in the proximal C-terminus of TASK-3 is required for ER export and efficient surface expression; ADA mutation retains channels in the ER; Sar1H79G (GTP-restricted) also retains TASK-3 in the ER, indicating COPII-dependent export; a second DAE motif has no effect on surface expression.","method":"Luminometric surface expression assay, live-cell GFP imaging in COS-7 cells, Xenopus oocyte voltage-clamp, Sar1 dominant-negative co-expression, chimeric Kir2.1-TASK-3 C-terminus constructs","journal":"Traffic (Copenhagen, Denmark)","confidence":"High","confidence_rationale":"Tier 1-2 — COPII dependence demonstrated, ER localization confirmed by live imaging, two orthogonal functional assays","pmids":["17547699"],"is_preprint":false},{"year":2007,"finding":"Kcnk9 (TASK-3) expression is maternally imprinted (paternal allele silenced) in mouse embryos and adult brain; the same imprinting is confirmed in human fetal brain; the CpG islands associated with Kcnk9 are hypomethylated rather than differentially methylated, suggesting imprinting may be regulated by the nearby Peg13 DMR.","method":"Allele-specific expression quantification by pyrosequencing (QUASEP) in F1 hybrid mice and human fetal brain, CpG island methylation analysis","journal":"Human molecular genetics","confidence":"High","confidence_rationale":"Tier 2 — allele-specific expression validated in reciprocal crosses and human tissue","pmids":["17704508"],"is_preprint":false},{"year":2009,"finding":"14-3-3 binding to the C-terminus of TASK-3 masks a tri-basic KRR retention motif; when 14-3-3 binding is disabled (by mutation), the KRR motif is exposed and binds COPI coatomer (demonstrated by GST pulldown), retaining channels in the Golgi; TASK-3 also possesses an independent N-terminal KR di-basic retention signal.","method":"GST pulldown of COPI coatomer, GFP-tagged channel localization by live imaging, dominant-negative channel co-expression, Xenopus oocyte voltage-clamp, mutational analysis","journal":"The Journal of physiology","confidence":"High","confidence_rationale":"Tier 1-2 — direct COPI binding demonstrated by pulldown, subcellular localization confirmed by imaging, mechanism explained by mutagenesis","pmids":["19139046"],"is_preprint":false},{"year":2009,"finding":"Heteromeric TASK-1/TASK-3 channels (identified by single-channel conductance and pharmacological profile) constitute ~75% of the oxygen-sensitive TASK-like background K+ conductance in rat carotid body glomus cells; hypoxia inhibits TASK-1/3 heteromers in native glomus cells.","method":"Single-channel outside-out and cell-attached patch-clamp in isolated glomus cells, comparison with cloned TASK-1, TASK-3, and TASK-1/3 tandem channels, ruthenium red and methanandamide pharmacology","journal":"The Journal of physiology","confidence":"High","confidence_rationale":"Tier 2 — native channel identity established by single-channel biophysics and pharmacology matched to cloned heterodimer","pmids":["19403596"],"is_preprint":false},{"year":2009,"finding":"TASK-3 gating occurs at both the selectivity filter (pH-sensitive) and a cytoplasmic inner gate; voltage-dependent gating reflects opening at the cytoplasmic mouth via M2 and M4 helix movements; mutations A237T (M4) and N133A (M2) increase open probability and shift voltage dependence; hinge glycines G117A and G231A reduce open probability, and none of these mutants alter pH sensitivity.","method":"Two-electrode voltage-clamp, single-channel patch-clamp, mutagenesis, kinetic modeling","journal":"The Journal of physiology","confidence":"High","confidence_rationale":"Tier 1 — systematic mutagenesis with single-channel kinetic modeling establishing dual gating mechanism","pmids":["19703964"],"is_preprint":false},{"year":2011,"finding":"Protein kinase A (PKA/cAMP-dependent kinase) phosphorylates Ser373 in the C-terminus of TASK-3 (K2P9.1); this phosphorylation enables 14-3-3 binding and promotes forward trafficking of TASK-3 to the plasma membrane; in vitro phosphorylation assays and cell-surface expression measurements confirm PKA as the relevant kinase.","method":"In vitro kinase phosphorylation assay, cell surface expression assay (GFP-tagged channels), whole-cell patch-clamp in HEK293 cells, bioinformatic candidate kinase identification","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — in vitro kinase assay plus functional surface expression and electrophysiological validation","pmids":["21357689"],"is_preprint":false},{"year":2011,"finding":"Covalent modification of Met159 in TASK-3 by NEM (M159C + NEM) irreversibly activates the channel and renders it resistant to inhibition by both acidic pH and active Gαq; bulky hydrophobic substitutions M159W and M159F mimic this effect; single-subunit modification in wild-type/M159C tandem dimers is sufficient for channel activation, with cross-talk between subunits.","method":"Cysteine-selective alkylation (NEM), site-directed mutagenesis, Ussing chamber ion flux in Fischer rat thyroid cells, tandem dimer constructs","journal":"Molecular pharmacology","confidence":"High","confidence_rationale":"Tier 1 — covalent modification coupled with mutagenesis identifies anesthetic regulatory site","pmids":["22147752"],"is_preprint":false},{"year":2012,"finding":"N-linked glycosylation at the conserved site in TASK-3 (K2P9.1) mildly reduces channel surface expression when disrupted, but has no detectable functional consequence on channel current, distinguishing TASK-3 from TASK-1 where glycosylation more strongly regulates surface density.","method":"Flow cytometry surface expression, patch-clamp electrophysiology, site-directed mutagenesis of glycosylation site, tunicamycin treatment","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 — orthogonal methods but limited functional effect and single lab","pmids":["23250752"],"is_preprint":false},{"year":2012,"finding":"Task3 knockout mice show depolarized adrenal glomerulosa cells (-52 mV vs. -79 mV in WT), abnormal Ca2+ signaling in glomerulosa cells, failure to suppress aldosterone under high Na+/low K+ diet, elevated aldosterone-renin ratio, and consequent salt-sensitive hypertension (~10 mmHg increase).","method":"Germline Task3 KO mouse, whole-cell electrophysiology in adrenal slices, Ca2+ imaging, adrenal aldosterone secretion assays, blood pressure measurement","journal":"Endocrinology","confidence":"High","confidence_rationale":"Tier 2 — clean KO with multiple orthogonal readouts establishing physiological role in aldosterone regulation","pmids":["22878402"],"is_preprint":false},{"year":2013,"finding":"G236R mutant TASK-3 (Birk Barel mutation) produces a small, inwardly rectifying current rather than the normal outward K+ current; mutant channels are differentially sensitive to extracellular acidification, zinc, and Gαq-coupled muscarinic receptor activation compared to WT; an additional A237T gain-of-function mutation or flufenamic acid can restore outward current through G236R channels.","method":"Whole-cell voltage-clamp in transfected cells, pharmacological profiling, double mutagenesis","journal":"Molecular pharmacology","confidence":"High","confidence_rationale":"Tier 1-2 — functional electrophysiology with mutagenesis and pharmacological rescue","pmids":["24342771"],"is_preprint":false},{"year":2013,"finding":"Neonatal Task3 KO mice display severe hyperaldosteronism with markedly elevated aldosterone, corticosterone, and progesterone; the most strongly upregulated gene in KO adrenals is renin, which is expressed in zona fasciculata, indicating activation of an intra-adrenal renin-angiotensin system as a consequence of Task3 loss.","method":"Germline Task3 KO mouse, plasma hormone measurements, real-time PCR, immunofluorescence for renin","journal":"Endocrinology","confidence":"High","confidence_rationale":"Tier 2 — clean KO with molecular pathway identification","pmids":["23698720"],"is_preprint":false},{"year":2014,"finding":"TASK-3 channels are highly enriched in a subpopulation of TRPM8-expressing cold thermoreceptor neurons; TASK-3 blockade or TASK-3 KO lowers cold threshold and produces hypersensitivity to cold, demonstrating TASK-3 sets the thermal threshold of cold receptors.","method":"BAC transgenesis, FACS purification, molecular profiling, TASK-3 KO mouse, pharmacological blockade, cold behavioral assays","journal":"Cell reports","confidence":"High","confidence_rationale":"Tier 2 — KO and pharmacological blockade with defined behavioral phenotype, enrichment established by molecular profiling","pmids":["25199828"],"is_preprint":false},{"year":2014,"finding":"Neurotensin acting via NTS1 receptors inhibits TASK-3 K+ channels in dentate gyrus granule cells through Gαq/11 in a PLC/IP3/PKC-independent manner; co-immunoprecipitation shows direct association of Gαq/11 with TASK-3 upon NTS1 activation; this inhibition depolarizes granule cells and facilitates LTP at perforant path synapses.","method":"Whole-cell patch-clamp, co-immunoprecipitation from brain slices, pharmacological dissection, LTP recording in hippocampal slices","journal":"Cerebral cortex","confidence":"High","confidence_rationale":"Tier 2 — direct protein-protein interaction confirmed by co-IP plus functional patch-clamp and LTP readout","pmids":["25405940"],"is_preprint":false},{"year":2015,"finding":"Breathing stimulant compounds PKTHPP, A1899, and doxapram inhibit TASK-3 by binding at a common site within the intracellular pore region; mutations L122D and G236D increase PKTHPP IC50 >1000-fold; the Birk Barel G236R disease mutation maps to this drug-binding site.","method":"Alanine-scan and charge-reversal mutagenesis, Ussing chamber ion flux in Fischer rat thyroid cells expressing TASK-3, homology modeling and molecular docking","journal":"Molecular pharmacology","confidence":"High","confidence_rationale":"Tier 1 — systematic mutagenesis across predicted binding site with quantitative pharmacology","pmids":["26268529"],"is_preprint":false},{"year":2016,"finding":"A monoclonal antibody (Y4) targeting the TASK-3 extracellular domain induces channel internalization in KCNK9-expressing carcinoma cells, reducing cell viability; systemic Y4 administration inhibits lung cancer xenograft growth and breast cancer metastasis in mice through cell-autonomous and immune-dependent cytotoxicity.","method":"Monoclonal antibody development, channel internalization assay, cell viability assay, xenograft and metastasis mouse models","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 — functional antibody-mediated channel internalization linked to tumor phenotype in vivo","pmids":["26842342"],"is_preprint":false},{"year":2017,"finding":"TASK-3 channels are present in the inner mitochondrial membrane of aldosterone-producing zona glomerulosa cells; yeast 2-hybrid, co-immunoprecipitation, and electron microscopy confirm mitochondrial localization; mitochondrial TASK-3 regulates mitochondrial morphology, mitochondrial membrane potential, and aldosterone production.","method":"Yeast two-hybrid, co-immunoprecipitation, electron microscopy immunogold labeling, mitochondrial membrane potential assay, aldosterone secretion measurements in KO cells","journal":"Hypertension","confidence":"High","confidence_rationale":"Tier 1-2 — three orthogonal methods confirm mitochondrial localization plus functional consequence","pmids":["28630209"],"is_preprint":false},{"year":2017,"finding":"Terbinafine selectively activates TASK-3 (pEC50 6.2 in thallium flux assay) but not TASK-1, TASK-2, TREK2, THIK1, TWIK1, or TRESK; activation confirmed by whole-cell patch-clamp; terbinafine also potentiates the disease-associated G236R TASK-3 mutant current.","method":"Thallium flux assay, whole-cell patch-clamp electrophysiology, selectivity screening across K2P channels","journal":"Biochemical and biophysical research communications","confidence":"High","confidence_rationale":"Tier 1 — pharmacological activity confirmed in two assay systems with selectivity panel","pmids":["28882594"],"is_preprint":false},{"year":2018,"finding":"KCC2 (K-Cl cotransporter) interacts directly with TASK-3 (KCNK9) channels and is required for their membrane expression; KCC2 knockdown in rat dentate gyrus downregulates TASK-3 membrane localization, depolarizes resting membrane potential, and increases neuronal excitability, altering dentate gyrus rhythmogenesis.","method":"Co-immunoprecipitation, KCC2 knockdown (shRNA), patch-clamp electrophysiology, in vivo LFP recordings in dentate gyrus","journal":"Cell reports","confidence":"High","confidence_rationale":"Tier 2 — direct protein-protein interaction by co-IP, functional consequence of KD on TASK-3 surface expression and neuronal physiology","pmids":["31269453"],"is_preprint":false},{"year":2018,"finding":"TWIK-1 and TASK-3 form heterodimeric channels in dentate gyrus granule cells; co-immunoprecipitation from mouse hippocampus and COS-7 cells confirms association; shRNA-mediated silencing demonstrates these heterodimers carry outwardly rectifying currents and contribute to intrinsic excitability; NT-NTSR1 signaling depolarizes granule cells by inhibiting TWIK-1/TASK-3 heterodimers.","method":"Co-immunoprecipitation, shRNA knockdown, whole-cell patch-clamp, neurotensin pharmacology in brain slices","journal":"Experimental & molecular medicine","confidence":"High","confidence_rationale":"Tier 2 — reciprocal co-IP plus shRNA functional validation in native tissue","pmids":["30416196"],"is_preprint":false},{"year":2020,"finding":"Withaferin A inhibits TASK-3 channel activity in a dose-dependent, voltage-independent manner; molecular docking and mutagenesis identify binding residues F125 and L197 in the channel pore; F125A, L197V, and F125A-L197V mutations markedly reduce WFA inhibition; WFA cytotoxicity on MDA-MB-231 breast cancer cells depends on TASK-3 expression.","method":"Whole-cell patch-clamp, molecular docking, site-directed mutagenesis, shRNA knockdown, cell viability assay","journal":"Biomedicine & pharmacotherapy","confidence":"High","confidence_rationale":"Tier 1 — mutagenesis confirms binding site predicted by docking; functional and cellular consequences validated","pmids":["32563149"],"is_preprint":false},{"year":2022,"finding":"KCNK9 imprinting syndrome variants cause both gain-of-function and loss-of-function changes in TASK-3 conductance, but the most consistent functional impact is altered channel regulation; a recurrent mutational hotspot at p.Arg131 was identified in addition to G236R.","method":"In vitro electrophysiology of 15 novel variants, 3D molecular modeling, sequence-based analysis, clinical genetics","journal":"Genome medicine","confidence":"High","confidence_rationale":"Tier 1-2 — electrophysiological characterization of 15 variants with structural modeling and clinical correlation","pmids":["35698242"],"is_preprint":false},{"year":2023,"finding":"Imprinted chromatin structure at the Peg13-Kcnk9 locus is established by allele-specific CTCF binding to the Peg13 DMR; allelic higher-order chromatin structure (mapped by region capture Hi-C) precedes imprinted expression of Kcnk9 during neuronal differentiation; activation of a distal enhancer induces imprinted Kcnk9 expression only in the presence of this allelic chromatin structure.","method":"Region capture Hi-C in reciprocal hybrid mouse crosses, in vitro neuron differentiation, allele-specific chromatin analysis, CTCF binding analysis","journal":"Genes & development","confidence":"High","confidence_rationale":"Tier 2 — Hi-C with reciprocal crosses and in vitro differentiation system establish causal relationship between chromatin structure and imprinted expression","pmids":["37821107"],"is_preprint":false},{"year":2024,"finding":"Cryo-EM structures of human TASK-3 at neutral and acidic pH reveal that extracellular acidification induces C-type inactivation characterized by selectivity filter dilation and simultaneous hydrophobic gate closure; His98 protonation shifts the conformational equilibrium toward C-type inactivation via a cation-π interaction with Trp78, validated by molecular dynamics and mutagenesis.","method":"Cryo-EM structure determination at neutral and acidic pH, molecular dynamics simulations, site-directed mutagenesis with electrophysiology","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1 — cryo-EM structures plus MD and mutagenesis, orthogonal validation of gating mechanism","pmids":["38630723"],"is_preprint":false},{"year":2024,"finding":"Cryo-EM structures of both human TASK-1 and TASK-3 (including the G236R KIS variant) resolved; structural analysis reveals a conserved lower X-gate as a hotspot for disease-causing mutations; G236R structural defect provides mechanistic insight into how channel gating is disrupted in KCNK9 imprinting syndrome.","method":"Cryo-EM structure determination, functional electrophysiology of X-gate mutants, structural comparison of WT and G236R TASK-3","journal":"Structure (London, England : 1993)","confidence":"High","confidence_rationale":"Tier 1 — cryo-EM structures of WT and disease variant with functional validation of gating mechanism","pmids":["39637865"],"is_preprint":false},{"year":2024,"finding":"TASK-5 (KCNK15) forms functional heterodimers with TASK-3; TASK-5 alone is non-functional but heteromeric TASK-5/TASK-3 complexes at the plasma membrane show altered single-channel conductance, modified Gq-coupled receptor inhibition, and altered sensitivity to TASK modulators compared to TASK-3 homodimers.","method":"Heterologous co-expression, single-channel patch-clamp, Gq receptor pharmacology, surface expression assays","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 — functional heterodimer confirmed by single-channel recordings and pharmacological profiling","pmids":["39215006"],"is_preprint":false}],"current_model":"KCNK9 (TASK-3/K2P9.1) encodes a constitutively active background K+ leak channel that functions as a homodimer or heterodimer (with TASK-1, TASK-5, or TWIK-1) at the plasma membrane and inner mitochondrial membrane; extracellular proton sensing is mediated by His98 (via a cation-π interaction with Trp78) coupled to C-type inactivation at the selectivity filter, while a cytoplasmic X-gate provides a second gating mechanism; surface expression is controlled by PKA-dependent phosphorylation of Ser373 enabling 14-3-3 binding that masks COPI retention signals, and by a di-acidic EDE motif promoting COPII-dependent ER export; channel activity is inhibited by Gαq (direct coupling, PKC-independent) and PKCα (phosphorylation of Thr341), and activated by volatile anesthetics and TNFα; the channel's K+ conductance is required for its oncogenic properties, its role in setting aldosterone secretion and membrane potential in adrenal glomerulosa cells, its contribution to cold thermosensation, and its regulation of neuronal excitability; loss-of-function mutations in the maternally expressed allele (notably G236R at the X-gate) cause KCNK9 imprinting syndrome."},"narrative":{"teleology":[{"year":2000,"claim":"Establishing that KCNK9 encodes a constitutively open, pH-sensitive background K⁺ channel answered the fundamental question of what type of conductance this gene produces and identified His98 as the extracellular pH sensor.","evidence":"Heterologous expression in COS-7 cells and Xenopus oocytes with patch-clamp and H98D mutagenesis","pmids":["10734076","10747866"],"confidence":"High","gaps":["Structural basis of His98 pH sensing not yet resolved","Native tissue relevance not demonstrated"]},{"year":2001,"claim":"Demonstrating that TASK-3 forms functional heterodimers with TASK-1, showing intermediate pharmacological properties, established that K2P channel diversity arises from combinatorial subunit assembly.","evidence":"Tandem-linked TASK-3/TASK-1 constructs in oocytes, pharmacological profiling with ruthenium red and pH","pmids":["11733509"],"confidence":"High","gaps":["Stoichiometry and structural arrangement of heterodimers unknown","Relative abundance of homo- vs. heterodimers in native tissue not quantified"]},{"year":2002,"claim":"Identifying the VLRFLT cytoplasmic interface region as required for both volatile anesthetic activation and receptor-mediated inhibition revealed a shared gating control point, while the discovery that 14-3-3 proteins bind a C-terminal RRxSx motif to promote surface trafficking established the first trafficking mechanism for TASK-3.","evidence":"Systematic mutagenesis with halothane/TRH modulation; two-hybrid and co-IP of 14-3-3 with truncation mutants and oocyte electrophysiology","pmids":["11886861","12433946"],"confidence":"High","gaps":["Identity of the kinase phosphorylating the 14-3-3 binding site not yet known","Structural mechanism of anesthetic binding not resolved"]},{"year":2003,"claim":"The demonstration that K⁺ conductance is required for TASK-3 oncogenic properties (G95E pore-dead mutant abolishes tumor formation) and that KCNK9 is amplified/overexpressed in breast cancer established it as a bona fide oncogene and linked channel function to cell survival.","evidence":"Dominant-negative G95E mutagenesis with patch-clamp, proliferation, apoptosis, and nude mouse xenograft assays; genomic amplification analysis in breast tumors","pmids":["12676587","12782791"],"confidence":"High","gaps":["Downstream signaling pathways linking K⁺ flux to survival not identified","Whether oncogenic role extends beyond breast cancer not established"]},{"year":2004,"claim":"Single-channel recordings from native cerebellar granule neurons confirmed that both homomeric TASK-3 and heteromeric TASK-1/TASK-3 channels exist in the brain, resolving the native identity of background K⁺ conductances and establishing Glu70 as a key residue for zinc and divalent cation sensitivity.","evidence":"Single-channel patch-clamp in native neurons matched to cloned channels; bidirectional mutagenesis of E70/K70 with zinc pharmacology","pmids":["14678492","15282272","15284350"],"confidence":"High","gaps":["Regional and cell-type distribution of homo- vs. heterodimers across brain not mapped","Physiological concentration of zinc at TASK-3-expressing synapses uncertain"]},{"year":2007,"claim":"Multiple advances resolved channel regulation and trafficking: Gαq directly inhibits TASK-3 independently of PKC (which instead opposes Gαq via Thr341 phosphorylation); a di-acidic EDE motif directs COPII-dependent ER export; the M1P1 loop containing E70 and H98 apposes the selectivity filter; and KCNK9 is maternally imprinted with the G236R loss-of-function mutation causing Birk-Barel syndrome.","evidence":"siRNA/inhibitor dissection of Gαq vs. PKC pathways; Sar1 dominant-negative and mutagenesis for COPII export; cysteine cross-linking and chimeras for pore architecture; genetic mapping and oocyte electrophysiology of G236R; allele-specific pyrosequencing in mouse and human for imprinting","pmids":["17374744","17547699","18418474","18678320","17704508"],"confidence":"High","gaps":["Structural basis of Gαq-channel interaction not resolved","How imprinting at the Peg13 locus controls KCNK9 expression mechanistically unclear"]},{"year":2009,"claim":"The discovery that 14-3-3 masks a COPI-binding KRR retention motif explained how phosphorylation-dependent 14-3-3 binding controls anterograde vs. retrograde trafficking, while dual gating at the selectivity filter and a cytoplasmic inner gate was established by systematic mutagenesis.","evidence":"GST pulldown of COPI coatomer from TASK-3 C-terminal peptides; single-channel kinetic modeling with M2/M4 hinge glycine and A237T mutations","pmids":["19139046","19703964"],"confidence":"High","gaps":["Whether COPI retrieval operates constitutively or is regulated in vivo unknown","Structural identity of the inner gate not visualized"]},{"year":2011,"claim":"Identification of PKA as the kinase phosphorylating Ser373 to enable 14-3-3 binding completed the trafficking signaling cascade from cAMP to channel surface expression.","evidence":"In vitro kinase assay, cell-surface expression measurement, and electrophysiology in HEK293 cells","pmids":["21357689"],"confidence":"High","gaps":["Whether PKA-dependent trafficking is regulated physiologically in specific cell types not shown","Phosphatase responsible for Ser373 dephosphorylation not identified"]},{"year":2012,"claim":"TASK-3 knockout mice revealed that the channel sets resting membrane potential in adrenal glomerulosa cells and is essential for aldosterone suppression, linking channel loss to hyperaldosteronism and salt-sensitive hypertension.","evidence":"Germline Task3 KO mouse with electrophysiology in adrenal slices, Ca²⁺ imaging, hormone measurements, blood pressure","pmids":["22878402","23698720"],"confidence":"High","gaps":["Relative contribution of plasma membrane vs. mitochondrial TASK-3 to aldosterone regulation unknown","Whether the phenotype reflects homo- or heteromeric channels not determined"]},{"year":2014,"claim":"TASK-3 enrichment in TRPM8⁺ cold thermoreceptors and the cold hypersensitivity of KO mice established a role in setting thermal thresholds, while Gαq/11 co-immunoprecipitation with TASK-3 in hippocampal slices confirmed the direct nature of receptor-mediated inhibition in native neurons.","evidence":"BAC-transgenic molecular profiling, KO mouse cold behavioral assays; co-IP from brain slices with neurotensin stimulation and LTP recordings","pmids":["25199828","25405940"],"confidence":"High","gaps":["Which Gαq interface residues contact the channel not mapped","Whether TASK-3 is the sole cold-threshold-setting leak channel in these neurons not resolved"]},{"year":2017,"claim":"TASK-3 localization to the inner mitochondrial membrane of glomerulosa cells, confirmed by immunogold EM, expanded the channel's functional repertoire beyond plasma membrane conductance to regulation of mitochondrial membrane potential and steroidogenesis.","evidence":"Yeast two-hybrid, co-IP, electron microscopy immunogold labeling, mitochondrial membrane potential assay","pmids":["28630209"],"confidence":"High","gaps":["How TASK-3 is targeted to mitochondria is unknown","Ion selectivity and gating of mitochondrial TASK-3 not characterized"]},{"year":2018,"claim":"Discovery that KCC2 directly interacts with TASK-3 and is required for its membrane expression in dentate gyrus neurons, and that TWIK-1/TASK-3 heterodimers carry outwardly rectifying currents in the same cells, revealed cell-type-specific partnership networks governing TASK-3 function.","evidence":"Co-IP from hippocampus, shRNA knockdown with patch-clamp and in vivo LFP recordings","pmids":["31269453","30416196"],"confidence":"High","gaps":["Molecular basis of KCC2–TASK-3 interaction not mapped","Relative abundance of TWIK-1/TASK-3 vs. TASK-1/TASK-3 heterodimers in dentate gyrus unknown"]},{"year":2022,"claim":"Electrophysiological characterization of 15 KCNK9 imprinting syndrome variants revealed that disease arises from both gain- and loss-of-function changes, with a recurrent hotspot at Arg131, broadening the genotype-phenotype spectrum beyond the original G236R finding.","evidence":"In vitro electrophysiology of patient-derived variants, 3D molecular modeling, clinical correlation","pmids":["35698242"],"confidence":"High","gaps":["How gain-of-function variants cause a similar clinical phenotype to loss-of-function variants not explained","No animal models of non-G236R variants"]},{"year":2023,"claim":"Allele-specific CTCF binding at the Peg13 DMR establishes higher-order chromatin structure that precedes and enables imprinted KCNK9 expression during neuronal differentiation, answering how epigenetic imprinting at a distal locus controls KCNK9 monoallelic expression.","evidence":"Region capture Hi-C in reciprocal hybrid mouse crosses with in vitro neuronal differentiation","pmids":["37821107"],"confidence":"High","gaps":["Whether the same chromatin mechanism operates in non-neuronal tissues not tested","Specific enhancer identity not fully resolved"]},{"year":2024,"claim":"Cryo-EM structures of TASK-3 at neutral and acidic pH revealed that protonation of His98 triggers a cation-π interaction with Trp78, causing C-type inactivation via selectivity filter dilation coupled to X-gate closure; structures of the G236R disease mutant showed how the X-gate is disrupted, and TASK-5/TASK-3 functional heterodimers were demonstrated.","evidence":"Cryo-EM at multiple pH values, molecular dynamics, mutagenesis with electrophysiology; cryo-EM of G236R variant; single-channel recordings of TASK-5/TASK-3 heterodimers","pmids":["38630723","39637865","39215006"],"confidence":"High","gaps":["No structure of TASK-3 bound to Gαq, anesthetics, or 14-3-3","How X-gate and selectivity filter gating are coordinated dynamically at atomic resolution remains incomplete"]},{"year":null,"claim":"Key unresolved questions include the structural basis of Gαq direct coupling to TASK-3, the mechanism of mitochondrial targeting and gating, the downstream signaling linking K⁺ conductance to oncogenic survival, and how both gain- and loss-of-function variants converge on the KCNK9 imprinting syndrome phenotype.","evidence":"","pmids":[],"confidence":"Low","gaps":["No structure of TASK-3 in complex with Gαq or anesthetic molecules","Mitochondrial targeting signal and import pathway not identified","Signaling cascade from K⁺ flux to apoptosis resistance unknown","Convergent pathophysiology of gain- and loss-of-function KIS variants unexplained"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0005215","term_label":"transporter activity","supporting_discovery_ids":[0,1,9,21,39]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[2,4,17,22,34]},{"term_id":"GO:0005739","term_label":"mitochondrion","supporting_discovery_ids":[32]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[13,29,22]},{"term_id":"R-HSA-112316","term_label":"Neuronal System","supporting_discovery_ids":[9,12,29,34,35]},{"term_id":"R-HSA-9609507","term_label":"Protein localization","supporting_discovery_ids":[17,19,22]}],"complexes":["TASK-3 homodimer","TASK-1/TASK-3 heterodimer","TWIK-1/TASK-3 heterodimer","TASK-5/TASK-3 heterodimer"],"partners":["KCNK3","KCNK1","KCNK15","YWHAZ","GNAQ","SLC12A5","COPA"],"other_free_text":[]},"mechanistic_narrative":"KCNK9 (TASK-3/K2P9.1) encodes a two-pore-domain background potassium leak channel that sets resting membrane potential in neurons, adrenal glomerulosa cells, carotid body glomus cells, and cold thermoreceptors, functioning as homodimers or heterodimers with TASK-1, TASK-5, or TWIK-1 [PMID:11733509, PMID:14678492, PMID:39215006, PMID:30416196]. Extracellular proton sensing is mediated by His98, which upon protonation engages a cation-π interaction with Trp78 to trigger C-type inactivation at the selectivity filter, while a distinct cytoplasmic X-gate formed by M2/M4 helices provides a second gating mechanism; channel surface expression depends on PKA phosphorylation of Ser373 enabling 14-3-3 binding that masks COPI retention signals, and a COPII-dependent di-acidic ER-export motif [PMID:38630723, PMID:19703964, PMID:21357689, PMID:19139046, PMID:17547699]. The channel is inhibited by direct Gαq coupling (PKC-independent) and by PKCα-mediated phosphorylation of Thr341, and activated by volatile anesthetics acting at the M4 cytoplasmic interface [PMID:17374744, PMID:11886861]. Loss-of-function mutations in the maternally expressed allele—notably G236R at the X-gate—cause KCNK9 imprinting syndrome (Birk-Barel syndrome), while gain of KCNK9 copy number or expression drives oncogenic transformation requiring intact K⁺ conductance [PMID:18678320, PMID:39637865, PMID:12676587, PMID:12782791]."},"prefetch_data":{"uniprot":{"accession":"Q9NPC2","full_name":"Potassium channel subfamily K member 9","aliases":["Acid-sensitive potassium channel protein TASK-3","TWIK-related acid-sensitive K(+) channel 3","Two pore potassium channel KT3.2","Two pore K(+) channel KT3.2"],"length_aa":374,"mass_kda":42.3,"function":"K(+) channel that conducts voltage-dependent outward rectifying currents upon membrane depolarization. Voltage sensing is coupled to K(+) electrochemical gradient in an 'ion flux gating' mode where outward but not inward ion flow opens the gate (PubMed:11042359, PubMed:11431495, PubMed:26919430, PubMed:38630723). Changes ion selectivity and becomes permeable to Na(+) ions in response to extracellular acidification. Protonation of the pH sensor His-98 stabilizes C-type inactivation conformation likely converting the channel from outward K(+)-conducting, to inward Na(+)-conducting to nonconductive state (PubMed:22948150, PubMed:38630723). Homo- and heterodimerizes to form functional channels with distinct regulatory and gating properties (By similarity) (PubMed:23169818, PubMed:38630723). Allows K(+) currents with fast-gating kinetics important for the repolarization and hyperpolarization phases of action potentials (By similarity). In granule neurons, hyperpolarizes the resting membrane potential to limit intrinsic neuronal excitability, but once the action potential threshold is reached, supports high-frequency action potential firing and increased neuronal excitability. Homomeric and/or heteromeric KCNK3:KCNK9 channels operate in cerebellar granule cells, whereas heteromeric KCNK1:KCNK9 enables currents in hippocampal dentate gyrus granule neurons (By similarity). Dispensable for central chemosensory respiration i.e. breathing controlled by brainstem CO2/pH, it rather conducts pH-sensitive currents and controls the firing rate of serotonergic raphe neurons involved in potentiation of the respiratory chemoreflex (By similarity). In retinal ganglion cells, mediates outward currents that regulate action potentials in response to acidification of the synaptic cleft. Involved in transmission of image-forming and nonimage-forming visual information in the retina (By similarity). In adrenal gland, contributes to the maintenance of a hyperpolarized resting membrane potential of aldosterone-producing cells at zona glomerulosa and limits aldosterone release as part of a regulatory mechanism that controls arterial blood pressure and electrolyte homeostasis (By similarity)","subcellular_location":"Cell membrane; Mitochondrion inner membrane; Cell projection, dendrite","url":"https://www.uniprot.org/uniprotkb/Q9NPC2/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/KCNK9","classification":"Not Classified","n_dependent_lines":2,"n_total_lines":1208,"dependency_fraction":0.0016556291390728477},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/KCNK9","total_profiled":1310},"omim":[{"mim_id":"613677","title":"HYPERALDOSTERONISM, FAMILIAL, TYPE III; HALD3","url":"https://www.omim.org/entry/613677"},{"mim_id":"612292","title":"BIRK-BAREL SYNDROME; BIBARS","url":"https://www.omim.org/entry/612292"},{"mim_id":"610873","title":"MENARCHE, AGE AT, QUANTITATIVE TRAIT LOCUS 1; MENAQ1","url":"https://www.omim.org/entry/610873"},{"mim_id":"607368","title":"POTASSIUM CHANNEL, SUBFAMILY K, MEMBER 15; KCNK15","url":"https://www.omim.org/entry/607368"},{"mim_id":"605874","title":"POTASSIUM CHANNEL, SUBFAMILY K, MEMBER 9; KCNK9","url":"https://www.omim.org/entry/605874"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Plasma membrane","reliability":"Approved"}],"tissue_specificity":"Tissue enriched","tissue_distribution":"Detected in some","driving_tissues":[{"tissue":"brain","ntpm":7.4}],"url":"https://www.proteinatlas.org/search/KCNK9"},"hgnc":{"alias_symbol":["K2p9.1","TASK3","TASK-3"],"prev_symbol":[]},"alphafold":{"accession":"Q9NPC2","domains":[{"cath_id":"1.10.287.70","chopping":"75-262","consensus_level":"high","plddt":92.2134,"start":75,"end":262},{"cath_id":"1.10.287","chopping":"1-54","consensus_level":"medium","plddt":94.2876,"start":1,"end":54}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9NPC2","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9NPC2-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9NPC2-F1-predicted_aligned_error_v6.png","plddt_mean":75.94},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=KCNK9","jax_strain_url":"https://www.jax.org/strain/search?query=KCNK9"},"sequence":{"accession":"Q9NPC2","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9NPC2.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9NPC2/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9NPC2"}},"corpus_meta":[{"pmid":"10734076","id":"PMC_10734076","title":"TASK-3, a new member of the tandem pore K(+) channel family.","date":"2000","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/10734076","citation_count":313,"is_preprint":false},{"pmid":"10747866","id":"PMC_10747866","title":"TASK-3, a novel tandem pore domain acid-sensitive K+ channel. 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thalamocortical neurons.","date":"2003","source":"The Journal of neuroscience : the official journal of the Society for Neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/12878686","citation_count":143,"is_preprint":false},{"pmid":"18678320","id":"PMC_18678320","title":"Maternally inherited Birk Barel mental retardation dysmorphism syndrome caused by a mutation in the genomically imprinted potassium channel KCNK9.","date":"2008","source":"American journal of human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/18678320","citation_count":142,"is_preprint":false},{"pmid":"19403596","id":"PMC_19403596","title":"Heteromeric TASK-1/TASK-3 is the major oxygen-sensitive background K+ channel in rat carotid body glomus cells.","date":"2009","source":"The Journal of physiology","url":"https://pubmed.ncbi.nlm.nih.gov/19403596","citation_count":128,"is_preprint":false},{"pmid":"12433946","id":"PMC_12433946","title":"Interaction with 14-3-3 proteins promotes functional expression of the potassium channels TASK-1 and TASK-3.","date":"2002","source":"The Journal of physiology","url":"https://pubmed.ncbi.nlm.nih.gov/12433946","citation_count":115,"is_preprint":false},{"pmid":"11749039","id":"PMC_11749039","title":"Expression pattern in brain of TASK-1, TASK-3, and a tandem pore domain K(+) channel subunit, TASK-5, associated with the central auditory nervous system.","date":"2001","source":"Molecular and cellular neurosciences","url":"https://pubmed.ncbi.nlm.nih.gov/11749039","citation_count":115,"is_preprint":false},{"pmid":"14678492","id":"PMC_14678492","title":"Functional expression of TASK-1/TASK-3 heteromers in cerebellar granule cells.","date":"2004","source":"The Journal of physiology","url":"https://pubmed.ncbi.nlm.nih.gov/14678492","citation_count":108,"is_preprint":false},{"pmid":"16760342","id":"PMC_16760342","title":"Membrane resting potential of thalamocortical relay neurons is shaped by the interaction among TASK3 and HCN2 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background channel with a single-channel conductance of 27 pS at -60 mV; extracellular pH sensitivity is conferred by histidine at position 98, as H98D mutation abolishes pH sensitivity; the channel is blocked by barium, quinidine, and lidocaine.\",\n      \"method\": \"Heterologous expression in COS-7 cells, whole-cell and single-channel patch-clamp, site-directed mutagenesis\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro electrophysiology with mutagenesis, replicated in two independent labs (PMID:10734076 and PMID:10747866)\",\n      \"pmids\": [\"10734076\", \"10747866\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"Histidine 98 in the extracellular pore region of TASK-3 acts as the pH sensor; substitution with asparagine or tyrosine abolishes pH sensitivity, and the residue is located at the outer pore adjacent to the selectivity filter.\",\n      \"method\": \"Xenopus oocyte expression, two-electrode voltage clamp, site-directed mutagenesis\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — mutagenesis with functional validation, replicated across two independent studies\",\n      \"pmids\": [\"10747866\", \"10734076\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"TASK-1 and TASK-3 form functional heterodimers when co-expressed in Xenopus oocytes; heterodimeric channels show intermediate pH sensitivity and TASK-1-like ruthenium red insensitivity; tandem-linked TASK-3/TASK-1 construct recapitulates heterodimer properties; epitope-tagged channels localize primarily to the plasma membrane in mammalian cells.\",\n      \"method\": \"Xenopus oocyte co-expression, two-electrode voltage clamp, tandem construct expression, immunostaining in mammalian cells\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — functional heterodimer confirmed by tandem construct, pharmacological profiling, and co-immunoprecipitation in follow-up studies; replicated across multiple labs\",\n      \"pmids\": [\"11733509\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Volatile anesthetic (halothane) activation and neurotransmitter (TRH) inhibition of TASK-3 both require a six-residue sequence at the cytoplasmic C-terminus/final transmembrane domain interface (VLRFLT region); mutations in this region abolish both modalities; a large portion of the C-terminus is additionally needed for full halothane and TRH effects on TASK-3.\",\n      \"method\": \"Site-directed mutagenesis, heterologous expression, whole-cell patch-clamp in Xenopus oocytes and mammalian cells\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — systematic mutagenesis with orthogonal pharmacological and receptor-mediated readouts\",\n      \"pmids\": [\"11886861\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"14-3-3 proteins interact with the conserved C-terminal pentapeptide motif (RRxSx) of TASK-3 and promote trafficking of the channel to the surface membrane; deletion of a single C-terminal amino acid abolishes 14-3-3 binding and strongly reduces macroscopic currents; TASK-1 and 14-3-3 co-immunoprecipitate from synaptic membrane extracts.\",\n      \"method\": \"Two-hybrid analysis, co-immunoprecipitation, Xenopus oocyte expression, surface expression assay, voltage-clamp, C-terminal truncation mutants\",\n      \"journal\": \"The Journal of physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal Co-IP and functional electrophysiology with mutagenesis, replicated by subsequent studies\",\n      \"pmids\": [\"12433946\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Ruthenium red inhibits TASK-3 by simultaneously binding to glutamate 70 of both subunits; mutation E70R or E70C abolishes inhibition; in tandem-linked homodimers, mutation of Glu70 in either subunit prevents RR action; Hill coefficient of 1 indicates a single polycationic molecule bridges both subunits; the reciprocal mutation K70E in TASK-1 confers RR sensitivity.\",\n      \"method\": \"Site-directed mutagenesis of tandem-linked and monomeric constructs, Xenopus oocyte expression, two-electrode voltage-clamp, Hill analysis\",\n      \"journal\": \"Molecular pharmacology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — reconstituted pharmacological mechanism with mutagenesis in tandem constructs, clear mechanistic model\",\n      \"pmids\": [\"12606773\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"KCNK9 is amplified (3–10-fold) in ~10% of breast tumors and overexpressed in 44%; overexpression in cell lines promotes tumor formation and confers resistance to hypoxia and serum deprivation, identifying KCNK9 as an oncogene at 8q24.3.\",\n      \"method\": \"Representational difference analysis, cell line overexpression, xenograft tumor formation assays, survival assays under hypoxia/serum deprivation\",\n      \"journal\": \"Cancer cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — loss/gain-of-function in cell lines with multiple phenotypic readouts; foundational oncology paper with >200 citations\",\n      \"pmids\": [\"12676587\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Potassium channel function of TASK3 is required for its oncogenic activities; a G95E pore mutation abolishes K+ current and abrogates proliferation in low serum, resistance to apoptosis, and tumor growth in nude mice; G95E acts as a dominant-negative, suppressing wild-type TASK3 current and tumorigenicity when co-expressed.\",\n      \"method\": \"Point mutagenesis (G95E), patch-clamp electrophysiology, cell proliferation and apoptosis assays, nude mouse xenograft\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — direct causal link established by dominant-negative mutagenesis with in vitro and in vivo readouts\",\n      \"pmids\": [\"12782791\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"TASK-1 and TASK-3 subunits co-immunoprecipitate from membranes of transfected mammalian cells; a dominant-negative TASK-1(Y191F) construct suppresses TASK-3 currents; heteromeric TASK-1/TASK-3 channels in hypoglossal motoneurons display pH and isoflurane sensitivities matching the heterodimer pharmacological profile.\",\n      \"method\": \"Co-immunoprecipitation, dominant-negative suppression, whole-cell patch-clamp in heterologous cells and native neurons, tandem construct expression\",\n      \"journal\": \"The Journal of neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal co-IP, dominant-negative, and native neuron recordings converge on same conclusion\",\n      \"pmids\": [\"15282272\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Native 38 pS background K+ channels in cerebellar granule neurons consist of both homomeric TASK-3 and heteromeric TASK-1/TASK-3; heteromers are distinguished by their ruthenium red insensitivity and intermediate pH sensitivity in single-channel recordings from native patches.\",\n      \"method\": \"Single-channel patch-clamp in COS-7 cells and native cerebellar granule neurons, pharmacological dissection with ruthenium red and pH\",\n      \"journal\": \"The Journal of physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — comparison of cloned and native channels with pharmacological fingerprinting in native cells\",\n      \"pmids\": [\"14678492\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Zinc selectively blocks TASK-3 (IC50 ~20 µM) but not TASK-1 or TASK-2; both E70 and H98 are critical for zinc block; E70K mutation abolishes zinc sensitivity of TASK-3, while the reverse K70E mutation confers zinc sensitivity to TASK-1; TASK-3/TASK-1 concatamer channels are zinc-insensitive, consistent with heterodimer formation.\",\n      \"method\": \"Site-directed mutagenesis, two-electrode voltage-clamp in Xenopus oocytes, concatamer channel expression\",\n      \"journal\": \"The Journal of physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — mutagenesis with pharmacological validation identifying two-site zinc binding mechanism\",\n      \"pmids\": [\"15284350\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Glutamate 70 of TASK-3 mediates sensitivity to extracellular divalent cations (Ca2+, Mg2+); replacing E70 with lysine or arginine abolishes divalent cation sensitivity; the reverse mutation K70E in TASK-1 confers divalent cation sensitivity; spermine and ruthenium red act similarly via E70 to decrease TASK-3 open probability.\",\n      \"method\": \"Mutagenesis, single-channel patch-clamp in HEK293 cells, whole-cell recordings in thalamocortical neurons\",\n      \"journal\": \"The Journal of physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — bidirectional mutagenesis with single-channel and native neuron validation\",\n      \"pmids\": [\"16513667\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Depolarization-induced Ca2+ entry via L-type channels activates the calcineurin pathway to upregulate TASK-3 transcription in cerebellar granule neurons; increased TASK-3 mRNA leads to elevated protein and IKso conductance, causing membrane hyperpolarization; blocking L-type Ca2+ channels or calcineurin abrogates TASK-3 expression and induces hyperexcitability.\",\n      \"method\": \"RT-PCR, pharmacological block of L-type channels (nifedipine) and calcineurin (FK506/cyclosporin A), patch-clamp electrophysiology in primary neurons\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple pharmacological interventions linking Ca2+ entry, calcineurin, transcription, and functional channel output\",\n      \"pmids\": [\"16864570\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Protein kinase C (PKCα) phosphorylates TASK-3 at Thr341 in the C-terminus, reducing channel current; Gαq-coupled M3 muscarinic receptor activation inhibits TASK-3 through a direct action of Gαq on the channel independent of PKC; PKC activation opposes rather than transduces Gαq-mediated inhibition.\",\n      \"method\": \"Gene silencing (siRNA), mutagenesis (T341A), whole-cell patch-clamp, Gαq antagonist (YM-254890), PKC inhibitors\",\n      \"journal\": \"Molecular pharmacology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — phosphorylation site identified by mutagenesis, pathway dissected with siRNA and selective inhibitors\",\n      \"pmids\": [\"17374744\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"TASK-3 (KCNK9) is maternally imprinted (paternal allele silenced); a missense mutation in the maternal copy (G236R) fully abolishes TASK-3 channel current both as a homodimer and as a heterodimer with K2P3.1, causing Birk Barel mental retardation dysmorphism syndrome.\",\n      \"method\": \"Genetic mapping, DNA sequencing, Xenopus oocyte electrophysiology of mutant channels, imprinting analysis\",\n      \"journal\": \"American journal of human genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic disease mechanism linked directly to loss of channel function by electrophysiology\",\n      \"pmids\": [\"18678320\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"TASK-3 KO mice show reduced sensitivity to halothane anesthetic and cannabinoid receptor agonist WIN55212-2 but unaltered responses to propofol, morphine, and lidocaine, demonstrating TASK-3's specific role in mediating select anesthetic and cannabinoid effects in vivo.\",\n      \"method\": \"Germline TASK-3 knockout mouse, pharmacological behavioral testing (halothane, cannabinoid, alpha-2 agonist, propofol, morphine, lidocaine)\",\n      \"journal\": \"The Journal of pharmacology and experimental therapeutics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean KO mouse with selective pharmacological phenotype across multiple drug classes\",\n      \"pmids\": [\"17875609\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"The M1P1 extracellular loop of TASK-3 apposes the selectivity filter; disulfide bridge formation between E70C in M1P1 and H98C in the pore confirmed proximity; M1P1 loop swap between TASK-1 and TASK-3 transfers pH sensitivity, demonstrating the loop regulates channel gating.\",\n      \"method\": \"Cysteine cross-linking with cadmium, dithiothreitol, M1P1 loop chimeras, mutagenesis, voltage-clamp in HEK cells\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — covalent cross-linking and chimera experiments establish structural proximity and functional role\",\n      \"pmids\": [\"18417474\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"A di-acidic EDE motif in the proximal C-terminus of TASK-3 is required for ER export and efficient surface expression; ADA mutation retains channels in the ER; Sar1H79G (GTP-restricted) also retains TASK-3 in the ER, indicating COPII-dependent export; a second DAE motif has no effect on surface expression.\",\n      \"method\": \"Luminometric surface expression assay, live-cell GFP imaging in COS-7 cells, Xenopus oocyte voltage-clamp, Sar1 dominant-negative co-expression, chimeric Kir2.1-TASK-3 C-terminus constructs\",\n      \"journal\": \"Traffic (Copenhagen, Denmark)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — COPII dependence demonstrated, ER localization confirmed by live imaging, two orthogonal functional assays\",\n      \"pmids\": [\"17547699\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Kcnk9 (TASK-3) expression is maternally imprinted (paternal allele silenced) in mouse embryos and adult brain; the same imprinting is confirmed in human fetal brain; the CpG islands associated with Kcnk9 are hypomethylated rather than differentially methylated, suggesting imprinting may be regulated by the nearby Peg13 DMR.\",\n      \"method\": \"Allele-specific expression quantification by pyrosequencing (QUASEP) in F1 hybrid mice and human fetal brain, CpG island methylation analysis\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — allele-specific expression validated in reciprocal crosses and human tissue\",\n      \"pmids\": [\"17704508\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"14-3-3 binding to the C-terminus of TASK-3 masks a tri-basic KRR retention motif; when 14-3-3 binding is disabled (by mutation), the KRR motif is exposed and binds COPI coatomer (demonstrated by GST pulldown), retaining channels in the Golgi; TASK-3 also possesses an independent N-terminal KR di-basic retention signal.\",\n      \"method\": \"GST pulldown of COPI coatomer, GFP-tagged channel localization by live imaging, dominant-negative channel co-expression, Xenopus oocyte voltage-clamp, mutational analysis\",\n      \"journal\": \"The Journal of physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — direct COPI binding demonstrated by pulldown, subcellular localization confirmed by imaging, mechanism explained by mutagenesis\",\n      \"pmids\": [\"19139046\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Heteromeric TASK-1/TASK-3 channels (identified by single-channel conductance and pharmacological profile) constitute ~75% of the oxygen-sensitive TASK-like background K+ conductance in rat carotid body glomus cells; hypoxia inhibits TASK-1/3 heteromers in native glomus cells.\",\n      \"method\": \"Single-channel outside-out and cell-attached patch-clamp in isolated glomus cells, comparison with cloned TASK-1, TASK-3, and TASK-1/3 tandem channels, ruthenium red and methanandamide pharmacology\",\n      \"journal\": \"The Journal of physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — native channel identity established by single-channel biophysics and pharmacology matched to cloned heterodimer\",\n      \"pmids\": [\"19403596\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"TASK-3 gating occurs at both the selectivity filter (pH-sensitive) and a cytoplasmic inner gate; voltage-dependent gating reflects opening at the cytoplasmic mouth via M2 and M4 helix movements; mutations A237T (M4) and N133A (M2) increase open probability and shift voltage dependence; hinge glycines G117A and G231A reduce open probability, and none of these mutants alter pH sensitivity.\",\n      \"method\": \"Two-electrode voltage-clamp, single-channel patch-clamp, mutagenesis, kinetic modeling\",\n      \"journal\": \"The Journal of physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — systematic mutagenesis with single-channel kinetic modeling establishing dual gating mechanism\",\n      \"pmids\": [\"19703964\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Protein kinase A (PKA/cAMP-dependent kinase) phosphorylates Ser373 in the C-terminus of TASK-3 (K2P9.1); this phosphorylation enables 14-3-3 binding and promotes forward trafficking of TASK-3 to the plasma membrane; in vitro phosphorylation assays and cell-surface expression measurements confirm PKA as the relevant kinase.\",\n      \"method\": \"In vitro kinase phosphorylation assay, cell surface expression assay (GFP-tagged channels), whole-cell patch-clamp in HEK293 cells, bioinformatic candidate kinase identification\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro kinase assay plus functional surface expression and electrophysiological validation\",\n      \"pmids\": [\"21357689\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Covalent modification of Met159 in TASK-3 by NEM (M159C + NEM) irreversibly activates the channel and renders it resistant to inhibition by both acidic pH and active Gαq; bulky hydrophobic substitutions M159W and M159F mimic this effect; single-subunit modification in wild-type/M159C tandem dimers is sufficient for channel activation, with cross-talk between subunits.\",\n      \"method\": \"Cysteine-selective alkylation (NEM), site-directed mutagenesis, Ussing chamber ion flux in Fischer rat thyroid cells, tandem dimer constructs\",\n      \"journal\": \"Molecular pharmacology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — covalent modification coupled with mutagenesis identifies anesthetic regulatory site\",\n      \"pmids\": [\"22147752\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"N-linked glycosylation at the conserved site in TASK-3 (K2P9.1) mildly reduces channel surface expression when disrupted, but has no detectable functional consequence on channel current, distinguishing TASK-3 from TASK-1 where glycosylation more strongly regulates surface density.\",\n      \"method\": \"Flow cytometry surface expression, patch-clamp electrophysiology, site-directed mutagenesis of glycosylation site, tunicamycin treatment\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — orthogonal methods but limited functional effect and single lab\",\n      \"pmids\": [\"23250752\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Task3 knockout mice show depolarized adrenal glomerulosa cells (-52 mV vs. -79 mV in WT), abnormal Ca2+ signaling in glomerulosa cells, failure to suppress aldosterone under high Na+/low K+ diet, elevated aldosterone-renin ratio, and consequent salt-sensitive hypertension (~10 mmHg increase).\",\n      \"method\": \"Germline Task3 KO mouse, whole-cell electrophysiology in adrenal slices, Ca2+ imaging, adrenal aldosterone secretion assays, blood pressure measurement\",\n      \"journal\": \"Endocrinology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean KO with multiple orthogonal readouts establishing physiological role in aldosterone regulation\",\n      \"pmids\": [\"22878402\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"G236R mutant TASK-3 (Birk Barel mutation) produces a small, inwardly rectifying current rather than the normal outward K+ current; mutant channels are differentially sensitive to extracellular acidification, zinc, and Gαq-coupled muscarinic receptor activation compared to WT; an additional A237T gain-of-function mutation or flufenamic acid can restore outward current through G236R channels.\",\n      \"method\": \"Whole-cell voltage-clamp in transfected cells, pharmacological profiling, double mutagenesis\",\n      \"journal\": \"Molecular pharmacology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — functional electrophysiology with mutagenesis and pharmacological rescue\",\n      \"pmids\": [\"24342771\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Neonatal Task3 KO mice display severe hyperaldosteronism with markedly elevated aldosterone, corticosterone, and progesterone; the most strongly upregulated gene in KO adrenals is renin, which is expressed in zona fasciculata, indicating activation of an intra-adrenal renin-angiotensin system as a consequence of Task3 loss.\",\n      \"method\": \"Germline Task3 KO mouse, plasma hormone measurements, real-time PCR, immunofluorescence for renin\",\n      \"journal\": \"Endocrinology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean KO with molecular pathway identification\",\n      \"pmids\": [\"23698720\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"TASK-3 channels are highly enriched in a subpopulation of TRPM8-expressing cold thermoreceptor neurons; TASK-3 blockade or TASK-3 KO lowers cold threshold and produces hypersensitivity to cold, demonstrating TASK-3 sets the thermal threshold of cold receptors.\",\n      \"method\": \"BAC transgenesis, FACS purification, molecular profiling, TASK-3 KO mouse, pharmacological blockade, cold behavioral assays\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — KO and pharmacological blockade with defined behavioral phenotype, enrichment established by molecular profiling\",\n      \"pmids\": [\"25199828\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Neurotensin acting via NTS1 receptors inhibits TASK-3 K+ channels in dentate gyrus granule cells through Gαq/11 in a PLC/IP3/PKC-independent manner; co-immunoprecipitation shows direct association of Gαq/11 with TASK-3 upon NTS1 activation; this inhibition depolarizes granule cells and facilitates LTP at perforant path synapses.\",\n      \"method\": \"Whole-cell patch-clamp, co-immunoprecipitation from brain slices, pharmacological dissection, LTP recording in hippocampal slices\",\n      \"journal\": \"Cerebral cortex\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — direct protein-protein interaction confirmed by co-IP plus functional patch-clamp and LTP readout\",\n      \"pmids\": [\"25405940\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Breathing stimulant compounds PKTHPP, A1899, and doxapram inhibit TASK-3 by binding at a common site within the intracellular pore region; mutations L122D and G236D increase PKTHPP IC50 >1000-fold; the Birk Barel G236R disease mutation maps to this drug-binding site.\",\n      \"method\": \"Alanine-scan and charge-reversal mutagenesis, Ussing chamber ion flux in Fischer rat thyroid cells expressing TASK-3, homology modeling and molecular docking\",\n      \"journal\": \"Molecular pharmacology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — systematic mutagenesis across predicted binding site with quantitative pharmacology\",\n      \"pmids\": [\"26268529\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"A monoclonal antibody (Y4) targeting the TASK-3 extracellular domain induces channel internalization in KCNK9-expressing carcinoma cells, reducing cell viability; systemic Y4 administration inhibits lung cancer xenograft growth and breast cancer metastasis in mice through cell-autonomous and immune-dependent cytotoxicity.\",\n      \"method\": \"Monoclonal antibody development, channel internalization assay, cell viability assay, xenograft and metastasis mouse models\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — functional antibody-mediated channel internalization linked to tumor phenotype in vivo\",\n      \"pmids\": [\"26842342\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"TASK-3 channels are present in the inner mitochondrial membrane of aldosterone-producing zona glomerulosa cells; yeast 2-hybrid, co-immunoprecipitation, and electron microscopy confirm mitochondrial localization; mitochondrial TASK-3 regulates mitochondrial morphology, mitochondrial membrane potential, and aldosterone production.\",\n      \"method\": \"Yeast two-hybrid, co-immunoprecipitation, electron microscopy immunogold labeling, mitochondrial membrane potential assay, aldosterone secretion measurements in KO cells\",\n      \"journal\": \"Hypertension\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — three orthogonal methods confirm mitochondrial localization plus functional consequence\",\n      \"pmids\": [\"28630209\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Terbinafine selectively activates TASK-3 (pEC50 6.2 in thallium flux assay) but not TASK-1, TASK-2, TREK2, THIK1, TWIK1, or TRESK; activation confirmed by whole-cell patch-clamp; terbinafine also potentiates the disease-associated G236R TASK-3 mutant current.\",\n      \"method\": \"Thallium flux assay, whole-cell patch-clamp electrophysiology, selectivity screening across K2P channels\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — pharmacological activity confirmed in two assay systems with selectivity panel\",\n      \"pmids\": [\"28882594\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"KCC2 (K-Cl cotransporter) interacts directly with TASK-3 (KCNK9) channels and is required for their membrane expression; KCC2 knockdown in rat dentate gyrus downregulates TASK-3 membrane localization, depolarizes resting membrane potential, and increases neuronal excitability, altering dentate gyrus rhythmogenesis.\",\n      \"method\": \"Co-immunoprecipitation, KCC2 knockdown (shRNA), patch-clamp electrophysiology, in vivo LFP recordings in dentate gyrus\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — direct protein-protein interaction by co-IP, functional consequence of KD on TASK-3 surface expression and neuronal physiology\",\n      \"pmids\": [\"31269453\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"TWIK-1 and TASK-3 form heterodimeric channels in dentate gyrus granule cells; co-immunoprecipitation from mouse hippocampus and COS-7 cells confirms association; shRNA-mediated silencing demonstrates these heterodimers carry outwardly rectifying currents and contribute to intrinsic excitability; NT-NTSR1 signaling depolarizes granule cells by inhibiting TWIK-1/TASK-3 heterodimers.\",\n      \"method\": \"Co-immunoprecipitation, shRNA knockdown, whole-cell patch-clamp, neurotensin pharmacology in brain slices\",\n      \"journal\": \"Experimental & molecular medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal co-IP plus shRNA functional validation in native tissue\",\n      \"pmids\": [\"30416196\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Withaferin A inhibits TASK-3 channel activity in a dose-dependent, voltage-independent manner; molecular docking and mutagenesis identify binding residues F125 and L197 in the channel pore; F125A, L197V, and F125A-L197V mutations markedly reduce WFA inhibition; WFA cytotoxicity on MDA-MB-231 breast cancer cells depends on TASK-3 expression.\",\n      \"method\": \"Whole-cell patch-clamp, molecular docking, site-directed mutagenesis, shRNA knockdown, cell viability assay\",\n      \"journal\": \"Biomedicine & pharmacotherapy\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — mutagenesis confirms binding site predicted by docking; functional and cellular consequences validated\",\n      \"pmids\": [\"32563149\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"KCNK9 imprinting syndrome variants cause both gain-of-function and loss-of-function changes in TASK-3 conductance, but the most consistent functional impact is altered channel regulation; a recurrent mutational hotspot at p.Arg131 was identified in addition to G236R.\",\n      \"method\": \"In vitro electrophysiology of 15 novel variants, 3D molecular modeling, sequence-based analysis, clinical genetics\",\n      \"journal\": \"Genome medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — electrophysiological characterization of 15 variants with structural modeling and clinical correlation\",\n      \"pmids\": [\"35698242\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Imprinted chromatin structure at the Peg13-Kcnk9 locus is established by allele-specific CTCF binding to the Peg13 DMR; allelic higher-order chromatin structure (mapped by region capture Hi-C) precedes imprinted expression of Kcnk9 during neuronal differentiation; activation of a distal enhancer induces imprinted Kcnk9 expression only in the presence of this allelic chromatin structure.\",\n      \"method\": \"Region capture Hi-C in reciprocal hybrid mouse crosses, in vitro neuron differentiation, allele-specific chromatin analysis, CTCF binding analysis\",\n      \"journal\": \"Genes & development\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — Hi-C with reciprocal crosses and in vitro differentiation system establish causal relationship between chromatin structure and imprinted expression\",\n      \"pmids\": [\"37821107\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Cryo-EM structures of human TASK-3 at neutral and acidic pH reveal that extracellular acidification induces C-type inactivation characterized by selectivity filter dilation and simultaneous hydrophobic gate closure; His98 protonation shifts the conformational equilibrium toward C-type inactivation via a cation-π interaction with Trp78, validated by molecular dynamics and mutagenesis.\",\n      \"method\": \"Cryo-EM structure determination at neutral and acidic pH, molecular dynamics simulations, site-directed mutagenesis with electrophysiology\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — cryo-EM structures plus MD and mutagenesis, orthogonal validation of gating mechanism\",\n      \"pmids\": [\"38630723\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Cryo-EM structures of both human TASK-1 and TASK-3 (including the G236R KIS variant) resolved; structural analysis reveals a conserved lower X-gate as a hotspot for disease-causing mutations; G236R structural defect provides mechanistic insight into how channel gating is disrupted in KCNK9 imprinting syndrome.\",\n      \"method\": \"Cryo-EM structure determination, functional electrophysiology of X-gate mutants, structural comparison of WT and G236R TASK-3\",\n      \"journal\": \"Structure (London, England : 1993)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — cryo-EM structures of WT and disease variant with functional validation of gating mechanism\",\n      \"pmids\": [\"39637865\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"TASK-5 (KCNK15) forms functional heterodimers with TASK-3; TASK-5 alone is non-functional but heteromeric TASK-5/TASK-3 complexes at the plasma membrane show altered single-channel conductance, modified Gq-coupled receptor inhibition, and altered sensitivity to TASK modulators compared to TASK-3 homodimers.\",\n      \"method\": \"Heterologous co-expression, single-channel patch-clamp, Gq receptor pharmacology, surface expression assays\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — functional heterodimer confirmed by single-channel recordings and pharmacological profiling\",\n      \"pmids\": [\"39215006\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"KCNK9 (TASK-3/K2P9.1) encodes a constitutively active background K+ leak channel that functions as a homodimer or heterodimer (with TASK-1, TASK-5, or TWIK-1) at the plasma membrane and inner mitochondrial membrane; extracellular proton sensing is mediated by His98 (via a cation-π interaction with Trp78) coupled to C-type inactivation at the selectivity filter, while a cytoplasmic X-gate provides a second gating mechanism; surface expression is controlled by PKA-dependent phosphorylation of Ser373 enabling 14-3-3 binding that masks COPI retention signals, and by a di-acidic EDE motif promoting COPII-dependent ER export; channel activity is inhibited by Gαq (direct coupling, PKC-independent) and PKCα (phosphorylation of Thr341), and activated by volatile anesthetics and TNFα; the channel's K+ conductance is required for its oncogenic properties, its role in setting aldosterone secretion and membrane potential in adrenal glomerulosa cells, its contribution to cold thermosensation, and its regulation of neuronal excitability; loss-of-function mutations in the maternally expressed allele (notably G236R at the X-gate) cause KCNK9 imprinting syndrome.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"KCNK9 (TASK-3/K2P9.1) encodes a two-pore-domain background potassium leak channel that sets resting membrane potential in neurons, adrenal glomerulosa cells, carotid body glomus cells, and cold thermoreceptors, functioning as homodimers or heterodimers with TASK-1, TASK-5, or TWIK-1 [PMID:11733509, PMID:14678492, PMID:39215006, PMID:30416196]. Extracellular proton sensing is mediated by His98, which upon protonation engages a cation-π interaction with Trp78 to trigger C-type inactivation at the selectivity filter, while a distinct cytoplasmic X-gate formed by M2/M4 helices provides a second gating mechanism; channel surface expression depends on PKA phosphorylation of Ser373 enabling 14-3-3 binding that masks COPI retention signals, and a COPII-dependent di-acidic ER-export motif [PMID:38630723, PMID:19703964, PMID:21357689, PMID:19139046, PMID:17547699]. The channel is inhibited by direct Gαq coupling (PKC-independent) and by PKCα-mediated phosphorylation of Thr341, and activated by volatile anesthetics acting at the M4 cytoplasmic interface [PMID:17374744, PMID:11886861]. Loss-of-function mutations in the maternally expressed allele—notably G236R at the X-gate—cause KCNK9 imprinting syndrome (Birk-Barel syndrome), while gain of KCNK9 copy number or expression drives oncogenic transformation requiring intact K⁺ conductance [PMID:18678320, PMID:39637865, PMID:12676587, PMID:12782791].\",\n  \"teleology\": [\n    {\n      \"year\": 2000,\n      \"claim\": \"Establishing that KCNK9 encodes a constitutively open, pH-sensitive background K⁺ channel answered the fundamental question of what type of conductance this gene produces and identified His98 as the extracellular pH sensor.\",\n      \"evidence\": \"Heterologous expression in COS-7 cells and Xenopus oocytes with patch-clamp and H98D mutagenesis\",\n      \"pmids\": [\"10734076\", \"10747866\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of His98 pH sensing not yet resolved\", \"Native tissue relevance not demonstrated\"]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"Demonstrating that TASK-3 forms functional heterodimers with TASK-1, showing intermediate pharmacological properties, established that K2P channel diversity arises from combinatorial subunit assembly.\",\n      \"evidence\": \"Tandem-linked TASK-3/TASK-1 constructs in oocytes, pharmacological profiling with ruthenium red and pH\",\n      \"pmids\": [\"11733509\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Stoichiometry and structural arrangement of heterodimers unknown\", \"Relative abundance of homo- vs. heterodimers in native tissue not quantified\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Identifying the VLRFLT cytoplasmic interface region as required for both volatile anesthetic activation and receptor-mediated inhibition revealed a shared gating control point, while the discovery that 14-3-3 proteins bind a C-terminal RRxSx motif to promote surface trafficking established the first trafficking mechanism for TASK-3.\",\n      \"evidence\": \"Systematic mutagenesis with halothane/TRH modulation; two-hybrid and co-IP of 14-3-3 with truncation mutants and oocyte electrophysiology\",\n      \"pmids\": [\"11886861\", \"12433946\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Identity of the kinase phosphorylating the 14-3-3 binding site not yet known\", \"Structural mechanism of anesthetic binding not resolved\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"The demonstration that K⁺ conductance is required for TASK-3 oncogenic properties (G95E pore-dead mutant abolishes tumor formation) and that KCNK9 is amplified/overexpressed in breast cancer established it as a bona fide oncogene and linked channel function to cell survival.\",\n      \"evidence\": \"Dominant-negative G95E mutagenesis with patch-clamp, proliferation, apoptosis, and nude mouse xenograft assays; genomic amplification analysis in breast tumors\",\n      \"pmids\": [\"12676587\", \"12782791\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Downstream signaling pathways linking K⁺ flux to survival not identified\", \"Whether oncogenic role extends beyond breast cancer not established\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Single-channel recordings from native cerebellar granule neurons confirmed that both homomeric TASK-3 and heteromeric TASK-1/TASK-3 channels exist in the brain, resolving the native identity of background K⁺ conductances and establishing Glu70 as a key residue for zinc and divalent cation sensitivity.\",\n      \"evidence\": \"Single-channel patch-clamp in native neurons matched to cloned channels; bidirectional mutagenesis of E70/K70 with zinc pharmacology\",\n      \"pmids\": [\"14678492\", \"15282272\", \"15284350\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Regional and cell-type distribution of homo- vs. heterodimers across brain not mapped\", \"Physiological concentration of zinc at TASK-3-expressing synapses uncertain\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Multiple advances resolved channel regulation and trafficking: Gαq directly inhibits TASK-3 independently of PKC (which instead opposes Gαq via Thr341 phosphorylation); a di-acidic EDE motif directs COPII-dependent ER export; the M1P1 loop containing E70 and H98 apposes the selectivity filter; and KCNK9 is maternally imprinted with the G236R loss-of-function mutation causing Birk-Barel syndrome.\",\n      \"evidence\": \"siRNA/inhibitor dissection of Gαq vs. PKC pathways; Sar1 dominant-negative and mutagenesis for COPII export; cysteine cross-linking and chimeras for pore architecture; genetic mapping and oocyte electrophysiology of G236R; allele-specific pyrosequencing in mouse and human for imprinting\",\n      \"pmids\": [\"17374744\", \"17547699\", \"18418474\", \"18678320\", \"17704508\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of Gαq-channel interaction not resolved\", \"How imprinting at the Peg13 locus controls KCNK9 expression mechanistically unclear\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"The discovery that 14-3-3 masks a COPI-binding KRR retention motif explained how phosphorylation-dependent 14-3-3 binding controls anterograde vs. retrograde trafficking, while dual gating at the selectivity filter and a cytoplasmic inner gate was established by systematic mutagenesis.\",\n      \"evidence\": \"GST pulldown of COPI coatomer from TASK-3 C-terminal peptides; single-channel kinetic modeling with M2/M4 hinge glycine and A237T mutations\",\n      \"pmids\": [\"19139046\", \"19703964\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether COPI retrieval operates constitutively or is regulated in vivo unknown\", \"Structural identity of the inner gate not visualized\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Identification of PKA as the kinase phosphorylating Ser373 to enable 14-3-3 binding completed the trafficking signaling cascade from cAMP to channel surface expression.\",\n      \"evidence\": \"In vitro kinase assay, cell-surface expression measurement, and electrophysiology in HEK293 cells\",\n      \"pmids\": [\"21357689\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether PKA-dependent trafficking is regulated physiologically in specific cell types not shown\", \"Phosphatase responsible for Ser373 dephosphorylation not identified\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"TASK-3 knockout mice revealed that the channel sets resting membrane potential in adrenal glomerulosa cells and is essential for aldosterone suppression, linking channel loss to hyperaldosteronism and salt-sensitive hypertension.\",\n      \"evidence\": \"Germline Task3 KO mouse with electrophysiology in adrenal slices, Ca²⁺ imaging, hormone measurements, blood pressure\",\n      \"pmids\": [\"22878402\", \"23698720\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Relative contribution of plasma membrane vs. mitochondrial TASK-3 to aldosterone regulation unknown\", \"Whether the phenotype reflects homo- or heteromeric channels not determined\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"TASK-3 enrichment in TRPM8⁺ cold thermoreceptors and the cold hypersensitivity of KO mice established a role in setting thermal thresholds, while Gαq/11 co-immunoprecipitation with TASK-3 in hippocampal slices confirmed the direct nature of receptor-mediated inhibition in native neurons.\",\n      \"evidence\": \"BAC-transgenic molecular profiling, KO mouse cold behavioral assays; co-IP from brain slices with neurotensin stimulation and LTP recordings\",\n      \"pmids\": [\"25199828\", \"25405940\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Which Gαq interface residues contact the channel not mapped\", \"Whether TASK-3 is the sole cold-threshold-setting leak channel in these neurons not resolved\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"TASK-3 localization to the inner mitochondrial membrane of glomerulosa cells, confirmed by immunogold EM, expanded the channel's functional repertoire beyond plasma membrane conductance to regulation of mitochondrial membrane potential and steroidogenesis.\",\n      \"evidence\": \"Yeast two-hybrid, co-IP, electron microscopy immunogold labeling, mitochondrial membrane potential assay\",\n      \"pmids\": [\"28630209\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How TASK-3 is targeted to mitochondria is unknown\", \"Ion selectivity and gating of mitochondrial TASK-3 not characterized\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Discovery that KCC2 directly interacts with TASK-3 and is required for its membrane expression in dentate gyrus neurons, and that TWIK-1/TASK-3 heterodimers carry outwardly rectifying currents in the same cells, revealed cell-type-specific partnership networks governing TASK-3 function.\",\n      \"evidence\": \"Co-IP from hippocampus, shRNA knockdown with patch-clamp and in vivo LFP recordings\",\n      \"pmids\": [\"31269453\", \"30416196\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular basis of KCC2–TASK-3 interaction not mapped\", \"Relative abundance of TWIK-1/TASK-3 vs. TASK-1/TASK-3 heterodimers in dentate gyrus unknown\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Electrophysiological characterization of 15 KCNK9 imprinting syndrome variants revealed that disease arises from both gain- and loss-of-function changes, with a recurrent hotspot at Arg131, broadening the genotype-phenotype spectrum beyond the original G236R finding.\",\n      \"evidence\": \"In vitro electrophysiology of patient-derived variants, 3D molecular modeling, clinical correlation\",\n      \"pmids\": [\"35698242\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How gain-of-function variants cause a similar clinical phenotype to loss-of-function variants not explained\", \"No animal models of non-G236R variants\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Allele-specific CTCF binding at the Peg13 DMR establishes higher-order chromatin structure that precedes and enables imprinted KCNK9 expression during neuronal differentiation, answering how epigenetic imprinting at a distal locus controls KCNK9 monoallelic expression.\",\n      \"evidence\": \"Region capture Hi-C in reciprocal hybrid mouse crosses with in vitro neuronal differentiation\",\n      \"pmids\": [\"37821107\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether the same chromatin mechanism operates in non-neuronal tissues not tested\", \"Specific enhancer identity not fully resolved\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Cryo-EM structures of TASK-3 at neutral and acidic pH revealed that protonation of His98 triggers a cation-π interaction with Trp78, causing C-type inactivation via selectivity filter dilation coupled to X-gate closure; structures of the G236R disease mutant showed how the X-gate is disrupted, and TASK-5/TASK-3 functional heterodimers were demonstrated.\",\n      \"evidence\": \"Cryo-EM at multiple pH values, molecular dynamics, mutagenesis with electrophysiology; cryo-EM of G236R variant; single-channel recordings of TASK-5/TASK-3 heterodimers\",\n      \"pmids\": [\"38630723\", \"39637865\", \"39215006\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No structure of TASK-3 bound to Gαq, anesthetics, or 14-3-3\", \"How X-gate and selectivity filter gating are coordinated dynamically at atomic resolution remains incomplete\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Key unresolved questions include the structural basis of Gαq direct coupling to TASK-3, the mechanism of mitochondrial targeting and gating, the downstream signaling linking K⁺ conductance to oncogenic survival, and how both gain- and loss-of-function variants converge on the KCNK9 imprinting syndrome phenotype.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No structure of TASK-3 in complex with Gαq or anesthetic molecules\", \"Mitochondrial targeting signal and import pathway not identified\", \"Signaling cascade from K⁺ flux to apoptosis resistance unknown\", \"Convergent pathophysiology of gain- and loss-of-function KIS variants unexplained\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0005215\", \"supporting_discovery_ids\": [0, 1, 9, 21, 39]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [2, 4, 17, 22, 34]},\n      {\"term_id\": \"GO:0005739\", \"supporting_discovery_ids\": [32]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0382551\", \"supporting_discovery_ids\": [0, 9, 21, 39]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [13, 29, 22]},\n      {\"term_id\": \"R-HSA-112316\", \"supporting_discovery_ids\": [9, 12, 29, 34, 35]},\n      {\"term_id\": \"R-HSA-9609507\", \"supporting_discovery_ids\": [17, 19, 22]}\n    ],\n    \"complexes\": [\n      \"TASK-3 homodimer\",\n      \"TASK-1/TASK-3 heterodimer\",\n      \"TWIK-1/TASK-3 heterodimer\",\n      \"TASK-5/TASK-3 heterodimer\"\n    ],\n    \"partners\": [\n      \"KCNK3\",\n      \"KCNK1\",\n      \"KCNK15\",\n      \"YWHAZ\",\n      \"GNAQ\",\n      \"SLC12A5\",\n      \"COPA\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}