{"gene":"KCNJ16","run_date":"2026-06-10T02:59:49","timeline":{"discoveries":[{"year":2000,"finding":"Kir5.1 (KCNJ16) does not form functional homomeric channels; it requires co-expression with Kir4.1 to produce functional heteromeric channels, and the Kir5.1 subunit confers extreme sensitivity to inhibition by intracellular acidification on the Kir5.1/Kir4.1 heteromer—a property not present in homomeric Kir4.1.","method":"Heterologous expression in Xenopus oocytes with two-electrode voltage clamp; Kir5.1-specific antibodies for localization in renal tubular epithelia","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro electrophysiology with defined subunit combinations, replicated across multiple independent labs (PMID:10764726, PMID:11306656, PMID:10790154)","pmids":["10764726"],"is_preprint":false},{"year":2000,"finding":"Hypercapnia inhibits Kir4.1-Kir5.1 heteromeric currents via intracellular acidification (not molecular CO2 directly); co-expression of Kir5.1 with Kir4.1 shifts the pKa from ~6.03 (homomeric Kir4.1) to ~7.45 (heteromeric Kir4.1-Kir5.1), placing it within the physiological pH range. A lysine residue at position 67 in the N-terminus of Kir4.1 (K67M mutation) completely eliminates CO2 sensitivity of both homomeric Kir4.1 and heteromeric Kir4.1-Kir5.1.","method":"Two-electrode voltage clamp and excised inside-out patches in Xenopus oocytes; site-directed mutagenesis (K67M)","journal":"The Journal of physiology","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro electrophysiology with mutagenesis, replicated in multiple studies (PMID:10790154, PMID:10871638)","pmids":["10790154","10871638"],"is_preprint":false},{"year":2000,"finding":"Heteromeric Kir4.1-Kir5.1 channels have a single-channel conductance of ~59 pS and open probability ~0.4 at pH 7.4; low pH selectively suppresses open-state probability without affecting single-channel conductance. PIP2 enhances baseline open probability and reduces pH sensitivity (shifts pKa from 7.45 to 7.22) of Kir4.1-Kir5.1 but not homomeric Kir4.1; this PIP2 effect requires Arg178 in Kir5.1.","method":"Inside-out patch-clamp in Xenopus oocytes; exogenous PIP2 application; site-directed mutagenesis (R178 in Kir5.1, K67M/Q in Kir4.1)","journal":"The Journal of general physiology","confidence":"High","confidence_rationale":"Tier 1 / Strong — single-channel reconstitution with mutagenesis and pharmacological dissection in one rigorous study","pmids":["10871638"],"is_preprint":false},{"year":2001,"finding":"Kir5.1 forms functional heteromeric channels with Kir4.2 (not only Kir4.1); Kir4.2 has a much higher intrinsic pH sensitivity (pKa ~7.1) than Kir4.1 (pKa ~5.99) due to a C-terminal mechanism, so co-expression with Kir5.1 does not cause a major pKa shift for Kir4.2-Kir5.1. However, Kir5.1 converts Kir4.2 from a high-open-probability (~0.9) channel into novel bursting channels (open probability <0.3) and increases single-channel conductance from ~25 pS to ~54 pS.","method":"Heterologous expression in Xenopus oocytes; cell-attached single-channel recording; pH titration experiments","journal":"The Journal of physiology","confidence":"High","confidence_rationale":"Tier 1 / Strong — single-channel electrophysiology with multiple orthogonal measurements (conductance, open probability, pH sensitivity) in one rigorous study","pmids":["11306656"],"is_preprint":false},{"year":2001,"finding":"Kir5.1, when co-expressed with Kir2.1, forms electrically silent heteromeric channels, thereby negatively suppressing Kir2.1 channel activity in native cells. Kir5.1 is efficiently targeted to the cell surface in Xenopus oocytes but forms silent channels with Kir2.1.","method":"Expression in Xenopus oocytes; electrophysiology; chromosomal mapping; in situ hybridization","journal":"FEBS letters","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — electrophysiological demonstration in oocytes, single lab, two methods (electrophysiology and co-expression)","pmids":["11240146"],"is_preprint":false},{"year":2002,"finding":"PSD-95 enables homomeric Kir5.1 channels to reach the plasma membrane and become functional: without PSD-95, Kir5.1 distributes mostly in the cytoplasm due to rapid internalization; with PSD-95 co-expression, Kir5.1 clusters on the plasma membrane and produces Ba2+-sensitive inwardly rectifying K+ currents. PKA-mediated phosphorylation of the Kir5.1 C-terminus prevents PSD-95 binding and promptly suppresses these currents.","method":"Co-transfection in HEK293T cells; electrophysiology; immunofluorescence; co-immunoprecipitation from brain tissue; PKA activation/inhibition","journal":"Neuron","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP from native brain tissue, functional electrophysiology, subcellular localization with defined consequence, and pharmacological dissection in one study","pmids":["11988170"],"is_preprint":false},{"year":2002,"finding":"Kir5.1 exhibits highly selective heteromultimerization: it physically associates with members of the Kir4.0 subfamily (Kir4.1, Kir4.2) but does not physically associate with Kir1.1, Kir2.1, or Kir6.2. Specific regions within the Kir4.1 subunit govern the selectivity of this interaction.","method":"Co-immunoprecipitation and functional expression in Xenopus oocytes; deletion/chimera mutagenesis of Kir subunits","journal":"American journal of physiology. Cell physiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP plus mutagenesis to identify interaction domains, single lab","pmids":["12456399"],"is_preprint":false},{"year":2003,"finding":"Residues at an intersubunit interface between the cytoplasmic domains of Kir5.1 and Kir4.1 are critical for the novel rectification, gating properties, and pH sensitivity of heteromeric Kir4.1/Kir5.1 channels, providing a structural mechanism for functional coupling of these properties in heteromeric channels.","method":"Site-directed mutagenesis combined with whole-cell and excised-patch electrophysiology in Xenopus oocytes","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — mutagenesis of intersubunit interface residues with functional electrophysiological validation, single lab with multiple mutants","pmids":["12923169"],"is_preprint":false},{"year":2004,"finding":"In mouse brain, Kir5.1 assembles differentially with Kir4.1 in a region-specific fashion: heteromeric Kir4.1/Kir5.1 is present in neocortex and olfactory bulb glomeruli, while homomeric Kir4.1 predominates in hippocampus and thalamus. Both channel types are expressed exclusively in astrocytes at membranes facing pia mater, blood vessels, and synaptic processes, and both associate with PDZ domain-containing syntrophins, implicated in subcellular targeting.","method":"Immunoprecipitation from mouse brain; immunolabeling with subunit-specific antibodies; co-immunoprecipitation with syntrophins","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal immunoprecipitation from native brain tissue with region-specific immunolabeling, replicated across multiple brain regions","pmids":["15310750"],"is_preprint":false},{"year":2004,"finding":"In the cochlear lateral wall, Kir5.1 is specifically expressed in type II, IV, and V fibrocytes of the spiral ligament (directly involved in K+ circulation), whereas Kir4.1 is exclusively in the stria vascularis—demonstrating that the two subunits occupy distinct regions and do not co-assemble in the cochlea, unlike in renal epithelia or retinal Müller cells.","method":"Immunohistochemistry with subunit-specific antibodies; double-immunolabeling; developmental expression analysis","journal":"The European journal of neuroscience","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct localization by immunostaining with specificity controls, single lab","pmids":["14750965"],"is_preprint":false},{"year":2007,"finding":"Heteromeric Kir4.1-Kir5.1 (but not homomeric Kir4.1) is strongly inhibited by PKC activation via reduction of open probability; this inhibition is independent of PIP2 depletion and PKC-dependent internalization. Multiple potential PKC phosphorylation sites exist in both Kir4.1 and Kir5.1 C-terminal peptides (phosphorylated in vitro), but individual site mutagenesis failed to abolish the effect, suggesting redundancy.","method":"Tandem dimer Kir4.1-Kir5.1 expressed in Xenopus oocytes; PMA (PKC activator) and specific PKC inhibitors; single-channel recordings; in vitro phosphorylation; site-directed mutagenesis","journal":"Biochimica et biophysica acta","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — electrophysiology with pharmacological dissection and in vitro phosphorylation, single lab","pmids":["17585871"],"is_preprint":false},{"year":2008,"finding":"Heteromeric Kir4.1-Kir5.1 is inhibited by serotonin (5-HT), substance-P, and thyrotropin-releasing hormone specifically through Gαq-protein-coupled receptors and downstream PKC activation; homomeric Kir4.1 is unaffected by these neurotransmitters. CO2/pH sensitivity of Kir4.1-Kir5.1 is preserved after neurotransmitter-induced inhibition.","method":"Xenopus oocyte expression; two-electrode voltage clamp; receptor pharmacology; PKC inhibitors; immunostaining in brainstem neurons","journal":"Journal of cellular physiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — pharmacological dissection in heterologous system with immunostaining in native neurons, single lab","pmids":["17559083"],"is_preprint":false},{"year":2008,"finding":"Kir4.1/Kir5.1 heterotetramer forms the predominant basolateral K+ channel (40 pS) in mouse cortical collecting duct principal cells, confirmed by co-localization of both subunit proteins with aquaporin-2 (principal cell marker) but absence from intercalated cells; channel activity is pH-sensitive with pK of 7.24 and is upregulated by Na+-depleted diet.","method":"Patch-clamp (cell-attached and inside-out), real-time PCR, immunohistochemistry, dietary manipulation","journal":"American journal of physiology. Renal physiology","confidence":"High","confidence_rationale":"Tier 2 / Strong — patch-clamp in native tubules plus immunohistochemistry and PCR, corroborated by dietary manipulation experiments","pmids":["18367659"],"is_preprint":false},{"year":2010,"finding":"Genetic deletion of Kcnj16 (Kir5.1) in mice dramatically reduces and delays the response of locus coeruleus neurons to cytoplasmic alkalinization and acidification, identifying Kir5.1 as a required determinant of PCO2/pH sensitivity in locus coeruleus neurons.","method":"Kcnj16 knockout mice; patch-clamp electrophysiology of locus coeruleus neurons in brain slices; pH manipulation","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean knockout with defined electrophysiological phenotype in native neurons","pmids":["21047793"],"is_preprint":false},{"year":2011,"finding":"Disruption of Kcnj16 (Kir5.1) in mice causes hypokalemic, hyperchloremic metabolic acidosis with hypercalciuria and exaggerated response to hydrochlorothiazide, indicating excessive Na+ absorption in the DCT. Loss of Kir5.1 abolishes pH sensitivity of basolateral K+ conductance in the DCT (remaining homomeric Kir4.1 has reduced pH sensitivity), establishing Kir5.1 as a pH-sensitive regulator of salt transport in the DCT.","method":"Targeted gene disruption (Kcnj16-/- mice); metabolic cage studies; patch-clamp electrophysiology of DCT basolateral membrane; pharmacological challenge (hydrochlorothiazide)","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean knockout with multiple orthogonal phenotypic and electrophysiological readouts","pmids":["21633011"],"is_preprint":false},{"year":2012,"finding":"S-glutathionylation of Cys158 in the TM2 helix of Kir5.1 is the mechanism by which oxidative stress (H2O2, diamide+GSH, GSSG) inhibits heteromeric Kir4.1-Kir5.1 but not homomeric Kir4.1. A single glutathione moiety at Cys158 is sufficient to block the channel; the modification is state-dependent (requires open channel) and accessible only to intracellular oxidants.","method":"HEK cell expression; whole-cell and inside-out patch-clamp; site-directed mutagenesis (C158A, C158T); tandem dimer constructs; biochemical GSH interaction assay","journal":"The Journal of physiology","confidence":"High","confidence_rationale":"Tier 1 / Strong — mutagenesis combined with electrophysiology and biochemical validation, multiple mutant constructs, state-dependence experiments","pmids":["22907060"],"is_preprint":false},{"year":2013,"finding":"Co-expression of KCNJ16 (Kir5.1) with the KCNJ10 (Kir4.1) p.A167V mutation in Xenopus oocytes almost completely abolishes heteromeric channel function, even though the p.A167V mutation alone retains large residual function as a homomeric channel—demonstrating that Kir5.1 can suppress a gain-of-function mutation and that in vitro assessment of KCNJ10 mutations may require co-expression with KCNJ16.","method":"Heterologous expression in Xenopus oocytes; two-electrode voltage clamp; Ba2+ inhibition assay; Western blot","journal":"Nephron. Physiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — electrophysiology with multiple mutant constructs plus protein expression analysis, single lab","pmids":["24193250"],"is_preprint":false},{"year":2017,"finding":"HNF1β directly transcriptionally activates Kcnj16 (Kir5.1): a conserved HNF1β-binding site in the Kcnj16 promoter drives 2.2-fold increased luciferase reporter expression; a disease-causing HNF1β mutant (p.Lys156Glu) fails to activate Kcnj16 expression; Hnf1β knockdown in mpkDCT cells reduces Kcnj16 by 38%, and renal HNF1β knockout mice show 78% reduction in Kcnj16 transcript.","method":"ChIP-seq; luciferase promoter assay; siRNA knockdown; HNF1β renal knockout mouse; qPCR","journal":"Kidney international","confidence":"High","confidence_rationale":"Tier 2 / Strong — ChIP-seq identification of binding site, functional promoter assay, knockdown, and knockout mouse model with consistent results across multiple orthogonal methods","pmids":["28577853"],"is_preprint":false},{"year":2017,"finding":"Kcnj16 knockout in Dahl salt-sensitive rats (SSKcnj16-/-) causes hypokalemia and reduced blood pressure; high-salt diet causes 100% mortality from salt wasting and severe hypokalemia. In knockout rats, Kir4.1 is upregulated but predominantly localizes to the cytosol rather than basolateral membrane. Benzamil (ENaC blocker) rescues mortality, while hydrochlorothiazide and furosemide do not, placing Kir5.1 upstream of ENaC-dependent Na+ transport in this context.","method":"Kcnj16 knockout rat (genetic deletion); electrophysiology of collecting duct; immunohistochemistry; dietary challenges; pharmacological rescue experiments","journal":"JCI insight","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean genetic knockout with multiple orthogonal readouts, pharmacological epistasis, and localization experiments","pmids":["28931751"],"is_preprint":false},{"year":2018,"finding":"Nedd4-2 binds to the phosphothreonine motif (TPVT, AA249-252) in the C-terminus of Kir5.1, and this interaction facilitates ubiquitination of Kir4.1 in the Kir4.1/Kir5.1 heterotetramer—reducing Kir4.1 membrane expression and K+ current. Nedd4-2 does not affect Kir4.1 in the absence of Kir5.1, and the Kir5.1 T249A mutation abolishes Nedd4-2 association and its inhibitory effect.","method":"Co-immunoprecipitation; GST pulldown; ubiquitination assay; patch-clamp; Western blot; site-directed mutagenesis (T249A); kidney-specific Nedd4-2 knockout mice","journal":"American journal of physiology. Renal physiology","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — Co-IP, GST pulldown, ubiquitination assay, mutagenesis, and in vivo knockout validation in one study","pmids":["29897283"],"is_preprint":false},{"year":2018,"finding":"Kir4.1/Kir5.1 activity in the DCT is essential for dietary sodium intake to regulate NCC: low sodium intake stimulates basolateral Kir4.1/Kir5.1, hyperpolarizes the DCT membrane, and upregulates NCC; high sodium intake has opposite effects. Kidney-specific Kir4.1 knockout abolishes the effect of dietary sodium intake on NCC activity, placing Kir4.1/Kir5.1 upstream of NCC in this regulatory pathway.","method":"Patch-clamp electrophysiology; immunoblotting; renal clearance; kidney-specific Kir4.1 knockout mice; dietary manipulation","journal":"Journal of the American Society of Nephrology : JASN","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic epistasis (kidney-specific KO) combined with electrophysiology and biochemical readouts","pmids":["30559144"],"is_preprint":false},{"year":2019,"finding":"Deletion of Kir5.1 abolishes the ability of dietary K+ intake to modulate basolateral DCT K+ conductance, DCT membrane potential, and NCC expression/activity; Kir5.1 KO mice cannot appropriately excrete K+ during high-K+ intake or conserve K+ during restriction, establishing Kir5.1 as essential for dietary K+-sensing regulation of NCC and K+ homeostasis.","method":"Kir5.1 knockout mice (Kcnj16-/-); patch-clamp electrophysiology; renal clearance; immunoblotting; high/low/normal K+ diets","journal":"Journal of the American Society of Nephrology : JASN","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean genetic knockout with electrophysiology, biochemical, and physiological readouts across dietary conditions","pmids":["31239388"],"is_preprint":false},{"year":2019,"finding":"Norepinephrine stimulates basolateral Kir4.1/Kir5.1 (40 pS channel) in the DCT via β-adrenergic receptor → cAMP → PKA signaling pathway; this activation hyperpolarizes the DCT membrane and is required for norepinephrine-induced upregulation of NCC, as the effect on NCC is absent in kidney-specific Kir4.1 knockout mice.","method":"Patch-clamp electrophysiology; pharmacological dissection (PKA inhibitors, isoproterenol, propranolol); immunoblotting; renal clearance; kidney-specific Kir4.1 KO mice","journal":"Hypertension","confidence":"High","confidence_rationale":"Tier 2 / Strong — pharmacological pathway dissection combined with genetic epistasis in Kir4.1-KO mice","pmids":["30571558"],"is_preprint":false},{"year":2019,"finding":"Kcnj16 mutation in Dahl SS rats blunts the ventilatory response to graded hypercapnic acidosis by up to 45% and nearly abolishes the hypoxic ventilatory response, establishing Kir5.1 as a key regulator of renal H+ handling and CO2/O2 chemoreflexes.","method":"Kcnj16 knockout Dahl SS rat; whole-body plethysmography; arterial blood gas measurement; pharmacological interventions (bicarbonate, hydrochlorothiazide, high-K+ diet)","journal":"FASEB journal","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean genetic knockout with quantitative physiological measurements and pharmacological rescue experiments","pmids":["30605394"],"is_preprint":false},{"year":2020,"finding":"Kidney-specific Nedd4-2 deletion increases Kir4.1/Kir5.1 activity and Kir4.1 membrane expression in the DCT, hyperpolarizes DCT membrane, and increases NCC expression/activity; double knockout of Nedd4-2 and Kir4.1 abolishes Nedd4-2 effects on K+ conductance and NCC, confirming that Nedd4-2 regulates NCC partly through Kir4.1/Kir5.1.","method":"Kidney-specific knockout mice (Nedd4-2 KO, Kir4.1 KO, double KO); electrophysiology; immunoblotting; immunostaining; renal clearance","journal":"Journal of the American Society of Nephrology : JASN","confidence":"High","confidence_rationale":"Tier 2 / Strong — double-knockout genetic epistasis with electrophysiology and biochemical readouts","pmids":["32295826"],"is_preprint":false},{"year":2021,"finding":"Kcnj16 knockout in Dahl SS rats causes audiogenic seizures (sound-induced tonic-clonic seizures confirmed by EEG); repeated seizure induction worsens hypokalemia and causes ~38% mortality in males. Dietary K+ supplementation mitigated hypokalemia and prevented seizure-related mortality but did not prevent seizures, identifying a non-redundant role for Kir5.1 in neuronal excitability control.","method":"Kcnj16 knockout rat; EEG recording; dietary K+ supplementation; behavioral testing","journal":"JCI insight","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean genetic model with EEG confirmation of seizures and pharmacological rescue demonstrating mechanism-phenotype link","pmids":["33232300"],"is_preprint":false},{"year":2021,"finding":"Mutations in KCNJ16 cause a novel human tubulopathy (hypokalemia, salt wasting, disturbed acid-base homeostasis, sensorineural deafness); co-expression of mutant KCNJ16 with KCNJ15 or KCNJ10 in Xenopus oocytes significantly reduces K+ currents, demonstrating that loss-of-function of heteromeric channels underlies the disease.","method":"Whole-exome sequencing; heterologous expression in Xenopus oocytes; two-electrode voltage clamp; surface expression assays","journal":"Journal of the American Society of Nephrology : JASN","confidence":"High","confidence_rationale":"Tier 2 / Strong — human genetics combined with functional electrophysiology in oocytes for multiple patient mutations","pmids":["33811157"],"is_preprint":false},{"year":2021,"finding":"Deletion of Kir5.1 abolishes the inhibitory effect of high Na+ intake on basolateral Kir4.1/Kir5.1 and NCC expression/activity in DCT, and prevents low-Na+-induced stimulation of these channels, demonstrating that Kir5.1 is required for dietary Na+-sensing regulation of NCC.","method":"Kir5.1 knockout mice; patch-clamp; immunoblotting; renal clearance; dietary Na+ manipulation","journal":"American journal of physiology. Renal physiology","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic knockout with electrophysiology and biochemical/physiological readouts under multiple dietary conditions","pmids":["33900854"],"is_preprint":false},{"year":2021,"finding":"Kcnj16 gene ablation in mice causes subfertility: 20% of Kir5.1 KO male mice are infertile, 50% of males >3 months cannot breed, testes are smaller, and a greater proportion of sperm display folded flagella (abnormal morphology). Kir5.1 is expressed in spermatozoa (Kir4.1 expressed in epididymal duct smooth muscle/epithelial cells), identifying Kir5.1 as important for sperm flagellar morphology and fertility.","method":"Kcnj16 knockout mice; fertility testing; histology; immunohistochemistry; sperm motility analysis","journal":"International journal of molecular sciences","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean knockout with quantitative fertility and morphological phenotyping, single lab","pmids":["34205849"],"is_preprint":false},{"year":2021,"finding":"Kir4.1/Kir5.1 heteromeric channels exhibit a novel intrinsic inward rectification mechanism in the absence of blocking cations (polyamines, Mg2+), generated by voltage-dependent K+-flux gating: inward K+ flux opens the gate, while outward flux cannot maintain the gate open. Saturating PIP2 greatly reduces this intrinsic rectification.","method":"HEK cell expression; excised inside-out patch-clamp; pharmacological removal of blocking cations; PIP2 application; site-directed mutagenesis","journal":"The Journal of general physiology","confidence":"High","confidence_rationale":"Tier 1 / Strong — rigorous single-channel biophysics with pharmacological isolation and mutagenesis","pmids":["33822868"],"is_preprint":false},{"year":2023,"finding":"Inhibition of calcineurin/PP2B by tacrolimus (FK506) or cyclosporine A stimulates Kir4.1/Kir5.1 in the DCT and upregulates NCC; FK506 effects require FKBP-12 (absent in FKBP-12 KO) while CsA does not, both pointing to PP2B inhibition as the mechanism. Src family protein tyrosine kinase activity is required for the stimulatory effect, and the effect on NCC is Kir4.1-dependent.","method":"Patch-clamp; immunoblotting; immunofluorescence; kidney-specific FKBP-12 KO and Kir4.1 KO mice; pharmacological dissection (SFK inhibitor, H2O2)","journal":"JCI insight","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple genetic knockouts, pharmacological dissection, and electrophysiology/biochemical readouts in one study","pmids":["36821372"],"is_preprint":false},{"year":2023,"finding":"Peripheral nerve injury decreases N6amt1 (DNA N6-methyladenine methyltransferase) in dorsal horn neurons, reducing m6A methylation at the Kcnj16 promoter, which upregulates Kcnj16 expression in the dorsal horn and contributes to neuropathic pain. Restoring N6amt1 reverses Kcnj16 upregulation and alleviates pain hypersensitivity; mimicking N6amt1 downregulation in naive mice elevates Kcnj16 and produces neuropathic pain-like behaviors.","method":"Spinal nerve ligation model; N6amt1 rescue (viral overexpression); m6A methylation analysis at Kcnj16 promoter; behavioral pain assays; N6amt1 knockdown in naive mice","journal":"Pain","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — epigenetic mechanism with gain and loss of function in vivo and promoter methylation analysis, single lab","pmids":["37624905"],"is_preprint":false},{"year":2025,"finding":"Kir5.1 is essential for assembly of the basolateral 50-pS K+ channel (Kir4.2/Kir5.1 heterotetramer) in the proximal tubule: the 50-pS channel is completely absent in Kir5.1 KO mice, and Kir4.2 expression and basolateral membrane staining are significantly reduced (while Kir4.1 in DCT is increased), resulting in depolarization of the proximal tubule membrane potential.","method":"Kir5.1 knockout mice; single-channel patch-clamp; immunoblotting; immunofluorescence; membrane potential recording","journal":"American journal of physiology. Renal physiology","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean genetic knockout with single-channel electrophysiology, immunolocalization, and membrane potential measurements providing convergent evidence","pmids":["39745541"],"is_preprint":false},{"year":2025,"finding":"Short-term (1-day) angiotensin-II-induced stimulation of NCC (via WNK4 and SPAK phosphorylation) depends on Kir4.1/Kir5.1 activity, as this effect is abolished in kidney-specific Kir4.1 KO mice. However, long-term (7-day) Ang-II can stimulate NCC by a Kir4.1/Kir5.1-independent mechanism.","method":"Kidney-specific AT1aR KO and Kir4.1 KO mice; patch-clamp; immunoblotting (pWNK4, pSPAK, pNCC, tNCC); renal clearance with thiazide","journal":"American journal of physiology. Renal physiology","confidence":"High","confidence_rationale":"Tier 2 / Strong — two genetic knockout models with electrophysiology and biochemical epistasis experiments, clear temporal dissection","pmids":["40241495"],"is_preprint":false},{"year":2026,"finding":"Activation of basolateral calcium-sensing receptor (CaSR) in the DCT inhibits Kir4.1/Kir5.1 and depolarizes the DCT membrane via PLC-PKC pathway; CaSR agonist R-568 effect is abolished by PLC or PKC inhibitors, and elevated extracellular Ca2+ (5 mM) similarly inhibits the channel by a PKC-dependent mechanism.","method":"Cell-attached patch-clamp in isolated DCT; CaSR agonists (R-568, neomycin); PLC inhibitor; PKC inhibitor (calphostin-C); Ca2+ manipulation","journal":"American journal of physiology. Renal physiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct patch-clamp in native DCT with pharmacological pathway dissection, single lab","pmids":["41886268"],"is_preprint":false}],"current_model":"KCNJ16/Kir5.1 is an inwardly rectifying K+ channel subunit that cannot form functional homomeric channels under most conditions, but obligately heteromerizes with Kir4.1 (in DCT/CNT/CCD/brain) or Kir4.2 (in proximal tubule) to form pH-sensitive basolateral K+ channels; Kir5.1 confers physiological-range intracellular pH sensitivity (pKa ~7.45) on these heteromers, enabling them to function as K+/pH sensors in the DCT that couple dietary K+ and Na+ intake to NCC activity via membrane potential changes, with channel activity regulated by Nedd4-2-mediated ubiquitination (through a C-terminal TPVT motif on Kir5.1), PKC (via Gαq-coupled receptors or CaSR), PKA (via β-adrenergic signaling), calcineurin/PP2B, PIP2, oxidative stress (S-glutathionylation of Cys158 in Kir5.1's TM2), and the scaffolding protein PSD-95 (which enables homomeric Kir5.1 plasma membrane expression in neurons); in vivo, loss of Kir5.1 disrupts renal salt handling, acid-base homeostasis, blood pressure control, CO2/O2 chemoreflexes, neuronal excitability (causing audiogenic seizures), and male fertility."},"narrative":{"mechanistic_narrative":"KCNJ16 encodes Kir5.1, an inwardly rectifying K+ channel subunit that does not form functional homomeric channels but obligately heteromerizes with members of the Kir4.0 subfamily (Kir4.1/KCNJ10 or Kir4.2/KCNJ15) to generate pH-sensitive basolateral K+ channels [PMID:10764726, PMID:12456399]. The defining functional contribution of Kir5.1 is to shift the intracellular pH sensitivity of these heteromers into the physiological range (pKa ~7.45 versus ~6 for homomeric Kir4.1), converting the channel into a K+/pH sensor, with the novel rectification and gating arising from an intersubunit interface between the cytoplasmic domains [PMID:10790154, PMID:10871638, PMID:11306656, PMID:12923169]. In the distal convoluted tubule, Kir4.1/Kir5.1 sets the basolateral membrane potential and acts as the upstream sensor that couples dietary Na+, K+, and acid-base status to NCC activity; loss of Kir5.1 abolishes the responsiveness of the DCT to dietary Na+ and K+ and disrupts NCC regulation [PMID:21633011, PMID:30559144, PMID:31239388, PMID:33900854]. In the proximal tubule Kir5.1 is required for assembly of the Kir4.2/Kir5.1 50-pS channel that maintains membrane polarization [PMID:39745541]. Channel activity is tuned by Nedd4-2-mediated ubiquitination acting through a C-terminal TPVT motif on Kir5.1, by PKC downstream of Gαq-coupled receptors and the calcium-sensing receptor, by β-adrenergic/PKA signaling, by calcineurin/PP2B, by PIP2, and by S-glutathionylation of Cys158 in TM2 during oxidative stress [PMID:29897283, PMID:41886268, PMID:30571558, PMID:36821372, PMID:10871638, PMID:22907060]. In the brain, Kir5.1 assembles with Kir4.1 in astrocytes in a region-specific manner and, via PSD-95, can reach the plasma membrane as a homomer [PMID:15310750, PMID:11988170]. Loss-of-function mutations in KCNJ16 cause a human tubulopathy comprising hypokalemia, salt wasting, disturbed acid-base homeostasis, and sensorineural deafness [PMID:33811157]; in rodents Kcnj16 deletion additionally impairs CO2/O2 chemoreflexes, causes audiogenic seizures, and reduces male fertility [PMID:30605394, PMID:33232300, PMID:34205849].","teleology":[{"year":2000,"claim":"Established that Kir5.1 is not an autonomous channel but a modulatory subunit that, by heteromerizing with Kir4.1, imposes physiological-range intracellular pH sensitivity on the resulting channel.","evidence":"Heterologous co-expression and voltage clamp in Xenopus oocytes with pH titration and K67M mutagenesis","pmids":["10764726","10790154","10871638"],"confidence":"High","gaps":["Did not establish the structural basis of how Kir5.1 raises the pKa","Endogenous heteromer composition in native tissue not yet defined"]},{"year":2000,"claim":"Resolved how Kir5.1 changes channel biophysics at the single-channel level and how PIP2 modulates pH gating, showing pH acts on open-state probability rather than conductance.","evidence":"Inside-out single-channel patch-clamp in oocytes with exogenous PIP2 and R178/K67 mutagenesis","pmids":["10871638"],"confidence":"High","gaps":["Structural location of the pH-sensing residues not defined","PIP2 binding site only mapped to a single residue"]},{"year":2001,"claim":"Showed that Kir5.1's partner specificity extends to Kir4.2 and that its assembly differentially reshapes gating depending on partner, distinguishing functional heteromerization from inhibitory silencing of non-partners.","evidence":"Single-channel recording of Kir4.2/Kir5.1 and Kir2.1/Kir5.1 co-expression in oocytes","pmids":["11306656","11240146"],"confidence":"High","gaps":["Physiological relevance of Kir2.1 silencing in native cells untested","Stoichiometry of heteromers not determined"]},{"year":2002,"claim":"Defined the selectivity rules for Kir5.1 assembly (Kir4.0 subfamily only) and identified PSD-95 as a scaffold that overcomes Kir5.1's rapid internalization to permit homomeric surface expression in neurons.","evidence":"Co-IP from brain tissue, chimera mutagenesis, and electrophysiology in HEK293T cells with PKA manipulation","pmids":["12456399","11988170"],"confidence":"High","gaps":["Whether homomeric Kir5.1/PSD-95 channels exist physiologically in vivo unclear","PKA phosphorylation site on Kir5.1 not precisely mapped"]},{"year":2003,"claim":"Localized the determinants of rectification, gating, and pH sensitivity to an intersubunit interface between the cytoplasmic domains, providing a structural rationale for functional coupling in the heteromer.","evidence":"Site-directed mutagenesis of interface residues with whole-cell and excised-patch electrophysiology in oocytes","pmids":["12923169"],"confidence":"High","gaps":["No high-resolution structure of the heteromeric interface","Single lab"]},{"year":2004,"claim":"Mapped the in vivo expression of Kir5.1 in astrocytes and cochlear fibrocytes, revealing region-specific co-assembly with Kir4.1 versus spatial segregation, indicating context-dependent channel composition.","evidence":"Immunoprecipitation and subunit-specific immunolabeling in mouse brain and cochlear lateral wall","pmids":["15310750","14750965"],"confidence":"High","gaps":["Functional consequence of regional heteromer/homomer balance untested","Syntrophin role in targeting only correlative"]},{"year":2008,"claim":"Identified post-translational regulatory inputs (PKC and Gαq-coupled neurotransmitter receptors) that selectively inhibit the heteromer, showing Kir5.1 confers signaling responsiveness absent from homomeric Kir4.1.","evidence":"Tandem-dimer oocyte expression with PMA, GPCR agonists, PKC inhibitors, and in vitro phosphorylation","pmids":["17585871","17559083"],"confidence":"Medium","gaps":["PKC phosphorylation sites not definitively mapped due to redundancy","Heterologous system; native DCT/neuron validation limited"]},{"year":2008,"claim":"Confirmed that Kir4.1/Kir5.1 is the predominant native basolateral K+ channel in collecting duct principal cells and is responsive to dietary salt, linking the channel to renal salt handling.","evidence":"Patch-clamp in native mouse cortical collecting duct with immunohistochemistry, qPCR, and dietary manipulation","pmids":["18367659"],"confidence":"High","gaps":["Causal upstream/downstream relationship to transporters not yet established","Cell-type restriction within nephron incomplete"]},{"year":2010,"claim":"Demonstrated genetically that Kir5.1 is a required determinant of neuronal pH/PCO2 chemosensitivity, moving the in vitro pH-sensor model into native neurons.","evidence":"Kcnj16 knockout mice with patch-clamp of locus coeruleus neurons under pH manipulation","pmids":["21047793"],"confidence":"High","gaps":["Whether residual Kir4.1 compensates incompletely characterized","Link to whole-animal respiratory behavior not yet made"]},{"year":2011,"claim":"Established the in vivo renal phenotype of Kir5.1 loss—hypokalemic hyperchloremic metabolic acidosis with enhanced DCT Na+ absorption—defining Kir5.1 as a pH-sensitive regulator of distal salt transport.","evidence":"Kcnj16 knockout mouse metabolic studies, DCT basolateral patch-clamp, and hydrochlorothiazide challenge","pmids":["21633011"],"confidence":"High","gaps":["Mechanism linking basolateral channel to apical NCC not yet defined","Acid-base versus salt contributions not fully separated"]},{"year":2012,"claim":"Identified S-glutathionylation of Cys158 in TM2 as the molecular mechanism coupling oxidative stress to selective inhibition of the heteromer.","evidence":"Whole-cell/inside-out patch-clamp in HEK cells with C158 mutagenesis, tandem dimers, and biochemical GSH assays","pmids":["22907060"],"confidence":"High","gaps":["In vivo relevance of Cys158 modification untested","Physiological oxidant sources not identified"]},{"year":2013,"claim":"Showed that Kir5.1 modulates the functional output of disease-relevant Kir4.1 mutations, with implications for how KCNJ10 variants are assessed.","evidence":"Co-expression of KCNJ16 with KCNJ10 p.A167V in oocytes with voltage clamp and Western blot","pmids":["24193250"],"confidence":"Medium","gaps":["Single lab heterologous assay","In vivo consequence of suppression untested"]},{"year":2017,"claim":"Identified upstream transcriptional control of Kcnj16 by HNF1β, connecting the channel to a developmental/renal transcription factor whose mutations cause kidney disease.","evidence":"ChIP-seq, luciferase promoter assay, siRNA knockdown, and renal HNF1β knockout mouse with qPCR","pmids":["28577853"],"confidence":"High","gaps":["Other transcriptional regulators not surveyed","Quantitative link from transcript reduction to channel function not measured"]},{"year":2017,"claim":"Demonstrated in a rat model that Kir5.1 loss causes life-threatening salt wasting and placed the channel upstream of ENaC-dependent Na+ transport via pharmacological epistasis.","evidence":"Kcnj16 knockout Dahl SS rat with collecting duct electrophysiology, IHC, dietary challenge, and benzamil/diuretic rescue","pmids":["28931751"],"confidence":"High","gaps":["Mechanism of Kir4.1 cytosolic mislocalization without Kir5.1 unclear","Species-specific differences from mouse not reconciled"]},{"year":2018,"claim":"Defined Nedd4-2 regulation of the channel, showing it binds the Kir5.1 C-terminal TPVT motif to ubiquitinate Kir4.1 and reduce surface expression—a Kir5.1-dependent degradative control point.","evidence":"Co-IP, GST pulldown, ubiquitination assay, T249A mutagenesis, patch-clamp, and kidney-specific Nedd4-2 KO mice","pmids":["29897283"],"confidence":"High","gaps":["Upstream signals controlling Nedd4-2 activity on this channel not defined","Phosphorylation state of TPVT motif in vivo not measured"]},{"year":2019,"claim":"Established the central physiological circuit: Kir4.1/Kir5.1 is the DCT sensor that translates dietary Na+ and K+ into membrane potential changes that set NCC activity, with Kir5.1 required for both Na+- and K+-sensing.","evidence":"Kir5.1 and kidney-specific Kir4.1 knockout mice with patch-clamp, immunoblotting, and renal clearance under varied diets","pmids":["31239388","30559144"],"confidence":"High","gaps":["Molecular link from membrane potential to WNK-SPAK-NCC cascade not fully resolved here","Relative weighting of K+ versus Na+ signals unclear"]},{"year":2019,"claim":"Identified hormonal (β-adrenergic/PKA) activation of the DCT channel as an NCC-regulatory input and demonstrated whole-animal chemoreflex deficits, broadening Kir5.1's physiological reach to blood pressure and respiratory control.","evidence":"DCT patch-clamp with PKA pharmacology and Kir4.1-KO mice; plethysmography and blood gas in Kcnj16-KO rats","pmids":["30571558","30605394"],"confidence":"High","gaps":["PKA phosphorylation target on the channel not mapped in vivo","Integration of renal and respiratory phenotypes incomplete"]},{"year":2020,"claim":"Confirmed by double-knockout epistasis that Nedd4-2 regulates NCC partly through Kir4.1/Kir5.1, integrating ubiquitin-mediated control into the salt-handling circuit.","evidence":"Kidney-specific Nedd4-2 KO, Kir4.1 KO, and double-KO mice with electrophysiology and biochemistry","pmids":["32295826"],"confidence":"High","gaps":["Nedd4-2 effects on NCC independent of the channel not fully quantified"]},{"year":2021,"claim":"Extended the channel's roles to neuronal excitability and reproduction, and—critically—established KCNJ16 mutations as the cause of a human tubulopathy with deafness through loss of heteromeric channel function.","evidence":"Kcnj16-KO rat EEG/seizure and KO-mouse fertility studies; human whole-exome sequencing with oocyte functional assays of patient mutations","pmids":["33232300","34205849","33811157"],"confidence":"High","gaps":["Cellular site of Kir5.1 action in seizures and sperm not defined","Genotype-phenotype correlation across patient mutations incomplete"]},{"year":2021,"claim":"Resolved a novel intrinsic, cation-independent inward rectification mechanism driven by voltage-dependent K+-flux gating, refining the biophysical model of the heteromer.","evidence":"Excised inside-out patch-clamp in HEK cells with removal of blocking cations, PIP2, and mutagenesis","pmids":["33822868"],"confidence":"High","gaps":["Structural gate underlying flux-dependent gating not identified"]},{"year":2023,"claim":"Added calcineurin/PP2B (via FKBP-12/Src) and CaSR-PLC-PKC as regulatory inputs and revealed an N6amt1/m6A epigenetic pathway controlling Kcnj16 in neuropathic pain, expanding the regulatory and pathophysiological repertoire.","evidence":"DCT patch-clamp with FK506/CsA and FKBP-12/Kir4.1 KO mice; spinal nerve ligation model with N6amt1 manipulation and promoter m6A analysis","pmids":["36821372","37624905"],"confidence":"Medium","gaps":["Direct molecular target of PP2B on the channel not identified","m6A/Kcnj16 pain mechanism from single lab"]},{"year":2025,"claim":"Demonstrated that Kir5.1 is required for assembly and basolateral targeting of the proximal-tubule Kir4.2/Kir5.1 50-pS channel and dissected the temporal dependence of angiotensin-II NCC stimulation on the channel.","evidence":"Kir5.1-KO mice with single-channel patch-clamp and membrane potential recording; AT1aR-KO and Kir4.1-KO mice with WNK4/SPAK/NCC phosphorylation epistasis","pmids":["39745541","40241495"],"confidence":"High","gaps":["Mechanism of the long-term, channel-independent Ang-II effect on NCC unknown","Proximal-tubule physiological consequences of channel loss incompletely defined"]},{"year":null,"claim":"A high-resolution structure of the Kir4.x/Kir5.1 heteromer and the precise molecular path from basolateral membrane potential to WNK-SPAK-NCC phosphorylation remain to be defined.","evidence":"","pmids":[],"confidence":"High","gaps":["No experimental structure of the heteromeric channel","Membrane-potential-to-WNK signaling step not molecularly resolved","Cellular substrate of seizure and fertility phenotypes unmapped"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0005215","term_label":"transporter activity","supporting_discovery_ids":[0,1,12,29]},{"term_id":"GO:0140299","term_label":"molecular sensor activity","supporting_discovery_ids":[1,13,14]},{"term_id":"GO:0008289","term_label":"lipid binding","supporting_discovery_ids":[2,29]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[5,8,12,18,32]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[5,18,32]}],"pathway":[{"term_id":"R-HSA-382551","term_label":"Transport of small molecules","supporting_discovery_ids":[14,20,21,27]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[11,22,30,34]},{"term_id":"R-HSA-112316","term_label":"Neuronal System","supporting_discovery_ids":[13,25]}],"complexes":["Kir4.1/Kir5.1 heterotetramer","Kir4.2/Kir5.1 heterotetramer"],"partners":["KCNJ10","KCNJ15","PSD-95","NEDD4L","SYNTROPHIN"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9NPI9","full_name":"Inward rectifier potassium channel 16","aliases":["Inward rectifier K(+) channel Kir5.1","Potassium channel, inwardly rectifying subfamily J member 16"],"length_aa":418,"mass_kda":47.9,"function":"Inward rectifier potassium channels are characterized by a greater tendency to allow potassium to flow into the cell rather than out of it. Their voltage dependence is regulated by the concentration of extracellular potassium; as external potassium is raised, the voltage range of the channel opening shifts to more positive voltages. The inward rectification is mainly due to the blockage of outward current by internal magnesium. KCNJ16 may be involved in the regulation of fluid and pH balance. In the kidney, together with KCNJ10, mediates basolateral K(+) recycling in distal tubules; this process is critical for Na(+) reabsorption at the tubules (PubMed:24561201)","subcellular_location":"Membrane; Basolateral cell membrane","url":"https://www.uniprot.org/uniprotkb/Q9NPI9/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/KCNJ16","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/KCNJ16","total_profiled":1310},"omim":[{"mim_id":"619406","title":"HYPOKALEMIC TUBULOPATHY AND DEAFNESS; HKTD","url":"https://www.omim.org/entry/619406"},{"mim_id":"614834","title":"THYROTOXIC PERIODIC PARALYSIS, SUSCEPTIBILITY TO, 3; TTPP3","url":"https://www.omim.org/entry/614834"},{"mim_id":"605722","title":"POTASSIUM CHANNEL, INWARDLY RECTIFYING, SUBFAMILY J, MEMBER 16; KCNJ16","url":"https://www.omim.org/entry/605722"},{"mim_id":"602887","title":"DISCS LARGE MAGUK SCAFFOLD PROTEIN 4; DLG4","url":"https://www.omim.org/entry/602887"},{"mim_id":"602208","title":"POTASSIUM CHANNEL, INWARDLY RECTIFYING, SUBFAMILY J, MEMBER 10; KCNJ10","url":"https://www.omim.org/entry/602208"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Uncertain","locations":[{"location":"Vesicles","reliability":"Uncertain"}],"tissue_specificity":"Group enriched","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"kidney","ntpm":182.2},{"tissue":"parathyroid gland","ntpm":251.5},{"tissue":"thyroid gland","ntpm":130.4}],"url":"https://www.proteinatlas.org/search/KCNJ16"},"hgnc":{"alias_symbol":["Kir5.1","BIR9"],"prev_symbol":[]},"alphafold":{"accession":"Q9NPI9","domains":[{"cath_id":"1.10.287.70","chopping":"71-174","consensus_level":"high","plddt":92.5108,"start":71,"end":174},{"cath_id":"2.60.40.1400","chopping":"179-344","consensus_level":"high","plddt":90.3402,"start":179,"end":344}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9NPI9","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9NPI9-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9NPI9-F1-predicted_aligned_error_v6.png","plddt_mean":78.12},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=KCNJ16","jax_strain_url":"https://www.jax.org/strain/search?query=KCNJ16"},"sequence":{"accession":"Q9NPI9","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9NPI9.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9NPI9/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9NPI9"}},"corpus_meta":[{"pmid":"15310750","id":"PMC_15310750","title":"Differential assembly of inwardly rectifying K+ channel subunits, Kir4.1 and Kir5.1, in brain astrocytes.","date":"2004","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/15310750","citation_count":142,"is_preprint":false},{"pmid":"11790808","id":"PMC_11790808","title":"An inward rectifier K(+) channel at the basolateral membrane of the mouse distal convoluted tubule: similarities with Kir4-Kir5.1 heteromeric channels.","date":"2002","source":"The Journal of physiology","url":"https://pubmed.ncbi.nlm.nih.gov/11790808","citation_count":138,"is_preprint":false},{"pmid":"20926613","id":"PMC_20926613","title":"Astrocytes in the retrotrapezoid nucleus sense H+ by inhibition of a Kir4.1-Kir5.1-like current and may contribute to chemoreception by a purinergic mechanism.","date":"2010","source":"Journal of neurophysiology","url":"https://pubmed.ncbi.nlm.nih.gov/20926613","citation_count":123,"is_preprint":false},{"pmid":"11306656","id":"PMC_11306656","title":"Differential pH sensitivity of Kir4.1 and Kir4.2 potassium channels and their modulation by heteropolymerisation with Kir5.1.","date":"2001","source":"The Journal of physiology","url":"https://pubmed.ncbi.nlm.nih.gov/11306656","citation_count":120,"is_preprint":false},{"pmid":"10764726","id":"PMC_10764726","title":"pH dependence of the inwardly rectifying potassium channel, Kir5.1, and localization in renal tubular epithelia.","date":"2000","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/10764726","citation_count":113,"is_preprint":false},{"pmid":"10790154","id":"PMC_10790154","title":"Modulation of kir4.1 and kir5.1 by hypercapnia and intracellular acidosis.","date":"2000","source":"The Journal of physiology","url":"https://pubmed.ncbi.nlm.nih.gov/10790154","citation_count":110,"is_preprint":false},{"pmid":"18367659","id":"PMC_18367659","title":"Kir4.1/Kir5.1 channel forms the major K+ channel in the basolateral membrane of mouse renal collecting duct principal cells.","date":"2008","source":"American journal of physiology. 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A lysine residue at position 67 in the N-terminus of Kir4.1 (K67M mutation) completely eliminates CO2 sensitivity of both homomeric Kir4.1 and heteromeric Kir4.1-Kir5.1.\",\n      \"method\": \"Two-electrode voltage clamp and excised inside-out patches in Xenopus oocytes; site-directed mutagenesis (K67M)\",\n      \"journal\": \"The Journal of physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro electrophysiology with mutagenesis, replicated in multiple studies (PMID:10790154, PMID:10871638)\",\n      \"pmids\": [\"10790154\", \"10871638\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"Heteromeric Kir4.1-Kir5.1 channels have a single-channel conductance of ~59 pS and open probability ~0.4 at pH 7.4; low pH selectively suppresses open-state probability without affecting single-channel conductance. PIP2 enhances baseline open probability and reduces pH sensitivity (shifts pKa from 7.45 to 7.22) of Kir4.1-Kir5.1 but not homomeric Kir4.1; this PIP2 effect requires Arg178 in Kir5.1.\",\n      \"method\": \"Inside-out patch-clamp in Xenopus oocytes; exogenous PIP2 application; site-directed mutagenesis (R178 in Kir5.1, K67M/Q in Kir4.1)\",\n      \"journal\": \"The Journal of general physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — single-channel reconstitution with mutagenesis and pharmacological dissection in one rigorous study\",\n      \"pmids\": [\"10871638\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"Kir5.1 forms functional heteromeric channels with Kir4.2 (not only Kir4.1); Kir4.2 has a much higher intrinsic pH sensitivity (pKa ~7.1) than Kir4.1 (pKa ~5.99) due to a C-terminal mechanism, so co-expression with Kir5.1 does not cause a major pKa shift for Kir4.2-Kir5.1. However, Kir5.1 converts Kir4.2 from a high-open-probability (~0.9) channel into novel bursting channels (open probability <0.3) and increases single-channel conductance from ~25 pS to ~54 pS.\",\n      \"method\": \"Heterologous expression in Xenopus oocytes; cell-attached single-channel recording; pH titration experiments\",\n      \"journal\": \"The Journal of physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — single-channel electrophysiology with multiple orthogonal measurements (conductance, open probability, pH sensitivity) in one rigorous study\",\n      \"pmids\": [\"11306656\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"Kir5.1, when co-expressed with Kir2.1, forms electrically silent heteromeric channels, thereby negatively suppressing Kir2.1 channel activity in native cells. Kir5.1 is efficiently targeted to the cell surface in Xenopus oocytes but forms silent channels with Kir2.1.\",\n      \"method\": \"Expression in Xenopus oocytes; electrophysiology; chromosomal mapping; in situ hybridization\",\n      \"journal\": \"FEBS letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — electrophysiological demonstration in oocytes, single lab, two methods (electrophysiology and co-expression)\",\n      \"pmids\": [\"11240146\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"PSD-95 enables homomeric Kir5.1 channels to reach the plasma membrane and become functional: without PSD-95, Kir5.1 distributes mostly in the cytoplasm due to rapid internalization; with PSD-95 co-expression, Kir5.1 clusters on the plasma membrane and produces Ba2+-sensitive inwardly rectifying K+ currents. PKA-mediated phosphorylation of the Kir5.1 C-terminus prevents PSD-95 binding and promptly suppresses these currents.\",\n      \"method\": \"Co-transfection in HEK293T cells; electrophysiology; immunofluorescence; co-immunoprecipitation from brain tissue; PKA activation/inhibition\",\n      \"journal\": \"Neuron\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP from native brain tissue, functional electrophysiology, subcellular localization with defined consequence, and pharmacological dissection in one study\",\n      \"pmids\": [\"11988170\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Kir5.1 exhibits highly selective heteromultimerization: it physically associates with members of the Kir4.0 subfamily (Kir4.1, Kir4.2) but does not physically associate with Kir1.1, Kir2.1, or Kir6.2. Specific regions within the Kir4.1 subunit govern the selectivity of this interaction.\",\n      \"method\": \"Co-immunoprecipitation and functional expression in Xenopus oocytes; deletion/chimera mutagenesis of Kir subunits\",\n      \"journal\": \"American journal of physiology. Cell physiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP plus mutagenesis to identify interaction domains, single lab\",\n      \"pmids\": [\"12456399\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Residues at an intersubunit interface between the cytoplasmic domains of Kir5.1 and Kir4.1 are critical for the novel rectification, gating properties, and pH sensitivity of heteromeric Kir4.1/Kir5.1 channels, providing a structural mechanism for functional coupling of these properties in heteromeric channels.\",\n      \"method\": \"Site-directed mutagenesis combined with whole-cell and excised-patch electrophysiology in Xenopus oocytes\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — mutagenesis of intersubunit interface residues with functional electrophysiological validation, single lab with multiple mutants\",\n      \"pmids\": [\"12923169\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"In mouse brain, Kir5.1 assembles differentially with Kir4.1 in a region-specific fashion: heteromeric Kir4.1/Kir5.1 is present in neocortex and olfactory bulb glomeruli, while homomeric Kir4.1 predominates in hippocampus and thalamus. Both channel types are expressed exclusively in astrocytes at membranes facing pia mater, blood vessels, and synaptic processes, and both associate with PDZ domain-containing syntrophins, implicated in subcellular targeting.\",\n      \"method\": \"Immunoprecipitation from mouse brain; immunolabeling with subunit-specific antibodies; co-immunoprecipitation with syntrophins\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal immunoprecipitation from native brain tissue with region-specific immunolabeling, replicated across multiple brain regions\",\n      \"pmids\": [\"15310750\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"In the cochlear lateral wall, Kir5.1 is specifically expressed in type II, IV, and V fibrocytes of the spiral ligament (directly involved in K+ circulation), whereas Kir4.1 is exclusively in the stria vascularis—demonstrating that the two subunits occupy distinct regions and do not co-assemble in the cochlea, unlike in renal epithelia or retinal Müller cells.\",\n      \"method\": \"Immunohistochemistry with subunit-specific antibodies; double-immunolabeling; developmental expression analysis\",\n      \"journal\": \"The European journal of neuroscience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct localization by immunostaining with specificity controls, single lab\",\n      \"pmids\": [\"14750965\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Heteromeric Kir4.1-Kir5.1 (but not homomeric Kir4.1) is strongly inhibited by PKC activation via reduction of open probability; this inhibition is independent of PIP2 depletion and PKC-dependent internalization. Multiple potential PKC phosphorylation sites exist in both Kir4.1 and Kir5.1 C-terminal peptides (phosphorylated in vitro), but individual site mutagenesis failed to abolish the effect, suggesting redundancy.\",\n      \"method\": \"Tandem dimer Kir4.1-Kir5.1 expressed in Xenopus oocytes; PMA (PKC activator) and specific PKC inhibitors; single-channel recordings; in vitro phosphorylation; site-directed mutagenesis\",\n      \"journal\": \"Biochimica et biophysica acta\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — electrophysiology with pharmacological dissection and in vitro phosphorylation, single lab\",\n      \"pmids\": [\"17585871\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Heteromeric Kir4.1-Kir5.1 is inhibited by serotonin (5-HT), substance-P, and thyrotropin-releasing hormone specifically through Gαq-protein-coupled receptors and downstream PKC activation; homomeric Kir4.1 is unaffected by these neurotransmitters. CO2/pH sensitivity of Kir4.1-Kir5.1 is preserved after neurotransmitter-induced inhibition.\",\n      \"method\": \"Xenopus oocyte expression; two-electrode voltage clamp; receptor pharmacology; PKC inhibitors; immunostaining in brainstem neurons\",\n      \"journal\": \"Journal of cellular physiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — pharmacological dissection in heterologous system with immunostaining in native neurons, single lab\",\n      \"pmids\": [\"17559083\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Kir4.1/Kir5.1 heterotetramer forms the predominant basolateral K+ channel (40 pS) in mouse cortical collecting duct principal cells, confirmed by co-localization of both subunit proteins with aquaporin-2 (principal cell marker) but absence from intercalated cells; channel activity is pH-sensitive with pK of 7.24 and is upregulated by Na+-depleted diet.\",\n      \"method\": \"Patch-clamp (cell-attached and inside-out), real-time PCR, immunohistochemistry, dietary manipulation\",\n      \"journal\": \"American journal of physiology. Renal physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — patch-clamp in native tubules plus immunohistochemistry and PCR, corroborated by dietary manipulation experiments\",\n      \"pmids\": [\"18367659\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Genetic deletion of Kcnj16 (Kir5.1) in mice dramatically reduces and delays the response of locus coeruleus neurons to cytoplasmic alkalinization and acidification, identifying Kir5.1 as a required determinant of PCO2/pH sensitivity in locus coeruleus neurons.\",\n      \"method\": \"Kcnj16 knockout mice; patch-clamp electrophysiology of locus coeruleus neurons in brain slices; pH manipulation\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean knockout with defined electrophysiological phenotype in native neurons\",\n      \"pmids\": [\"21047793\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Disruption of Kcnj16 (Kir5.1) in mice causes hypokalemic, hyperchloremic metabolic acidosis with hypercalciuria and exaggerated response to hydrochlorothiazide, indicating excessive Na+ absorption in the DCT. Loss of Kir5.1 abolishes pH sensitivity of basolateral K+ conductance in the DCT (remaining homomeric Kir4.1 has reduced pH sensitivity), establishing Kir5.1 as a pH-sensitive regulator of salt transport in the DCT.\",\n      \"method\": \"Targeted gene disruption (Kcnj16-/- mice); metabolic cage studies; patch-clamp electrophysiology of DCT basolateral membrane; pharmacological challenge (hydrochlorothiazide)\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean knockout with multiple orthogonal phenotypic and electrophysiological readouts\",\n      \"pmids\": [\"21633011\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"S-glutathionylation of Cys158 in the TM2 helix of Kir5.1 is the mechanism by which oxidative stress (H2O2, diamide+GSH, GSSG) inhibits heteromeric Kir4.1-Kir5.1 but not homomeric Kir4.1. A single glutathione moiety at Cys158 is sufficient to block the channel; the modification is state-dependent (requires open channel) and accessible only to intracellular oxidants.\",\n      \"method\": \"HEK cell expression; whole-cell and inside-out patch-clamp; site-directed mutagenesis (C158A, C158T); tandem dimer constructs; biochemical GSH interaction assay\",\n      \"journal\": \"The Journal of physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — mutagenesis combined with electrophysiology and biochemical validation, multiple mutant constructs, state-dependence experiments\",\n      \"pmids\": [\"22907060\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Co-expression of KCNJ16 (Kir5.1) with the KCNJ10 (Kir4.1) p.A167V mutation in Xenopus oocytes almost completely abolishes heteromeric channel function, even though the p.A167V mutation alone retains large residual function as a homomeric channel—demonstrating that Kir5.1 can suppress a gain-of-function mutation and that in vitro assessment of KCNJ10 mutations may require co-expression with KCNJ16.\",\n      \"method\": \"Heterologous expression in Xenopus oocytes; two-electrode voltage clamp; Ba2+ inhibition assay; Western blot\",\n      \"journal\": \"Nephron. Physiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — electrophysiology with multiple mutant constructs plus protein expression analysis, single lab\",\n      \"pmids\": [\"24193250\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"HNF1β directly transcriptionally activates Kcnj16 (Kir5.1): a conserved HNF1β-binding site in the Kcnj16 promoter drives 2.2-fold increased luciferase reporter expression; a disease-causing HNF1β mutant (p.Lys156Glu) fails to activate Kcnj16 expression; Hnf1β knockdown in mpkDCT cells reduces Kcnj16 by 38%, and renal HNF1β knockout mice show 78% reduction in Kcnj16 transcript.\",\n      \"method\": \"ChIP-seq; luciferase promoter assay; siRNA knockdown; HNF1β renal knockout mouse; qPCR\",\n      \"journal\": \"Kidney international\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — ChIP-seq identification of binding site, functional promoter assay, knockdown, and knockout mouse model with consistent results across multiple orthogonal methods\",\n      \"pmids\": [\"28577853\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Kcnj16 knockout in Dahl salt-sensitive rats (SSKcnj16-/-) causes hypokalemia and reduced blood pressure; high-salt diet causes 100% mortality from salt wasting and severe hypokalemia. In knockout rats, Kir4.1 is upregulated but predominantly localizes to the cytosol rather than basolateral membrane. Benzamil (ENaC blocker) rescues mortality, while hydrochlorothiazide and furosemide do not, placing Kir5.1 upstream of ENaC-dependent Na+ transport in this context.\",\n      \"method\": \"Kcnj16 knockout rat (genetic deletion); electrophysiology of collecting duct; immunohistochemistry; dietary challenges; pharmacological rescue experiments\",\n      \"journal\": \"JCI insight\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean genetic knockout with multiple orthogonal readouts, pharmacological epistasis, and localization experiments\",\n      \"pmids\": [\"28931751\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Nedd4-2 binds to the phosphothreonine motif (TPVT, AA249-252) in the C-terminus of Kir5.1, and this interaction facilitates ubiquitination of Kir4.1 in the Kir4.1/Kir5.1 heterotetramer—reducing Kir4.1 membrane expression and K+ current. Nedd4-2 does not affect Kir4.1 in the absence of Kir5.1, and the Kir5.1 T249A mutation abolishes Nedd4-2 association and its inhibitory effect.\",\n      \"method\": \"Co-immunoprecipitation; GST pulldown; ubiquitination assay; patch-clamp; Western blot; site-directed mutagenesis (T249A); kidney-specific Nedd4-2 knockout mice\",\n      \"journal\": \"American journal of physiology. Renal physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — Co-IP, GST pulldown, ubiquitination assay, mutagenesis, and in vivo knockout validation in one study\",\n      \"pmids\": [\"29897283\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Kir4.1/Kir5.1 activity in the DCT is essential for dietary sodium intake to regulate NCC: low sodium intake stimulates basolateral Kir4.1/Kir5.1, hyperpolarizes the DCT membrane, and upregulates NCC; high sodium intake has opposite effects. Kidney-specific Kir4.1 knockout abolishes the effect of dietary sodium intake on NCC activity, placing Kir4.1/Kir5.1 upstream of NCC in this regulatory pathway.\",\n      \"method\": \"Patch-clamp electrophysiology; immunoblotting; renal clearance; kidney-specific Kir4.1 knockout mice; dietary manipulation\",\n      \"journal\": \"Journal of the American Society of Nephrology : JASN\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic epistasis (kidney-specific KO) combined with electrophysiology and biochemical readouts\",\n      \"pmids\": [\"30559144\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Deletion of Kir5.1 abolishes the ability of dietary K+ intake to modulate basolateral DCT K+ conductance, DCT membrane potential, and NCC expression/activity; Kir5.1 KO mice cannot appropriately excrete K+ during high-K+ intake or conserve K+ during restriction, establishing Kir5.1 as essential for dietary K+-sensing regulation of NCC and K+ homeostasis.\",\n      \"method\": \"Kir5.1 knockout mice (Kcnj16-/-); patch-clamp electrophysiology; renal clearance; immunoblotting; high/low/normal K+ diets\",\n      \"journal\": \"Journal of the American Society of Nephrology : JASN\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean genetic knockout with electrophysiology, biochemical, and physiological readouts across dietary conditions\",\n      \"pmids\": [\"31239388\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Norepinephrine stimulates basolateral Kir4.1/Kir5.1 (40 pS channel) in the DCT via β-adrenergic receptor → cAMP → PKA signaling pathway; this activation hyperpolarizes the DCT membrane and is required for norepinephrine-induced upregulation of NCC, as the effect on NCC is absent in kidney-specific Kir4.1 knockout mice.\",\n      \"method\": \"Patch-clamp electrophysiology; pharmacological dissection (PKA inhibitors, isoproterenol, propranolol); immunoblotting; renal clearance; kidney-specific Kir4.1 KO mice\",\n      \"journal\": \"Hypertension\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — pharmacological pathway dissection combined with genetic epistasis in Kir4.1-KO mice\",\n      \"pmids\": [\"30571558\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Kcnj16 mutation in Dahl SS rats blunts the ventilatory response to graded hypercapnic acidosis by up to 45% and nearly abolishes the hypoxic ventilatory response, establishing Kir5.1 as a key regulator of renal H+ handling and CO2/O2 chemoreflexes.\",\n      \"method\": \"Kcnj16 knockout Dahl SS rat; whole-body plethysmography; arterial blood gas measurement; pharmacological interventions (bicarbonate, hydrochlorothiazide, high-K+ diet)\",\n      \"journal\": \"FASEB journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean genetic knockout with quantitative physiological measurements and pharmacological rescue experiments\",\n      \"pmids\": [\"30605394\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Kidney-specific Nedd4-2 deletion increases Kir4.1/Kir5.1 activity and Kir4.1 membrane expression in the DCT, hyperpolarizes DCT membrane, and increases NCC expression/activity; double knockout of Nedd4-2 and Kir4.1 abolishes Nedd4-2 effects on K+ conductance and NCC, confirming that Nedd4-2 regulates NCC partly through Kir4.1/Kir5.1.\",\n      \"method\": \"Kidney-specific knockout mice (Nedd4-2 KO, Kir4.1 KO, double KO); electrophysiology; immunoblotting; immunostaining; renal clearance\",\n      \"journal\": \"Journal of the American Society of Nephrology : JASN\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — double-knockout genetic epistasis with electrophysiology and biochemical readouts\",\n      \"pmids\": [\"32295826\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Kcnj16 knockout in Dahl SS rats causes audiogenic seizures (sound-induced tonic-clonic seizures confirmed by EEG); repeated seizure induction worsens hypokalemia and causes ~38% mortality in males. Dietary K+ supplementation mitigated hypokalemia and prevented seizure-related mortality but did not prevent seizures, identifying a non-redundant role for Kir5.1 in neuronal excitability control.\",\n      \"method\": \"Kcnj16 knockout rat; EEG recording; dietary K+ supplementation; behavioral testing\",\n      \"journal\": \"JCI insight\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean genetic model with EEG confirmation of seizures and pharmacological rescue demonstrating mechanism-phenotype link\",\n      \"pmids\": [\"33232300\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Mutations in KCNJ16 cause a novel human tubulopathy (hypokalemia, salt wasting, disturbed acid-base homeostasis, sensorineural deafness); co-expression of mutant KCNJ16 with KCNJ15 or KCNJ10 in Xenopus oocytes significantly reduces K+ currents, demonstrating that loss-of-function of heteromeric channels underlies the disease.\",\n      \"method\": \"Whole-exome sequencing; heterologous expression in Xenopus oocytes; two-electrode voltage clamp; surface expression assays\",\n      \"journal\": \"Journal of the American Society of Nephrology : JASN\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — human genetics combined with functional electrophysiology in oocytes for multiple patient mutations\",\n      \"pmids\": [\"33811157\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Deletion of Kir5.1 abolishes the inhibitory effect of high Na+ intake on basolateral Kir4.1/Kir5.1 and NCC expression/activity in DCT, and prevents low-Na+-induced stimulation of these channels, demonstrating that Kir5.1 is required for dietary Na+-sensing regulation of NCC.\",\n      \"method\": \"Kir5.1 knockout mice; patch-clamp; immunoblotting; renal clearance; dietary Na+ manipulation\",\n      \"journal\": \"American journal of physiology. Renal physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic knockout with electrophysiology and biochemical/physiological readouts under multiple dietary conditions\",\n      \"pmids\": [\"33900854\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Kcnj16 gene ablation in mice causes subfertility: 20% of Kir5.1 KO male mice are infertile, 50% of males >3 months cannot breed, testes are smaller, and a greater proportion of sperm display folded flagella (abnormal morphology). Kir5.1 is expressed in spermatozoa (Kir4.1 expressed in epididymal duct smooth muscle/epithelial cells), identifying Kir5.1 as important for sperm flagellar morphology and fertility.\",\n      \"method\": \"Kcnj16 knockout mice; fertility testing; histology; immunohistochemistry; sperm motility analysis\",\n      \"journal\": \"International journal of molecular sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean knockout with quantitative fertility and morphological phenotyping, single lab\",\n      \"pmids\": [\"34205849\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Kir4.1/Kir5.1 heteromeric channels exhibit a novel intrinsic inward rectification mechanism in the absence of blocking cations (polyamines, Mg2+), generated by voltage-dependent K+-flux gating: inward K+ flux opens the gate, while outward flux cannot maintain the gate open. Saturating PIP2 greatly reduces this intrinsic rectification.\",\n      \"method\": \"HEK cell expression; excised inside-out patch-clamp; pharmacological removal of blocking cations; PIP2 application; site-directed mutagenesis\",\n      \"journal\": \"The Journal of general physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — rigorous single-channel biophysics with pharmacological isolation and mutagenesis\",\n      \"pmids\": [\"33822868\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Inhibition of calcineurin/PP2B by tacrolimus (FK506) or cyclosporine A stimulates Kir4.1/Kir5.1 in the DCT and upregulates NCC; FK506 effects require FKBP-12 (absent in FKBP-12 KO) while CsA does not, both pointing to PP2B inhibition as the mechanism. Src family protein tyrosine kinase activity is required for the stimulatory effect, and the effect on NCC is Kir4.1-dependent.\",\n      \"method\": \"Patch-clamp; immunoblotting; immunofluorescence; kidney-specific FKBP-12 KO and Kir4.1 KO mice; pharmacological dissection (SFK inhibitor, H2O2)\",\n      \"journal\": \"JCI insight\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple genetic knockouts, pharmacological dissection, and electrophysiology/biochemical readouts in one study\",\n      \"pmids\": [\"36821372\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Peripheral nerve injury decreases N6amt1 (DNA N6-methyladenine methyltransferase) in dorsal horn neurons, reducing m6A methylation at the Kcnj16 promoter, which upregulates Kcnj16 expression in the dorsal horn and contributes to neuropathic pain. Restoring N6amt1 reverses Kcnj16 upregulation and alleviates pain hypersensitivity; mimicking N6amt1 downregulation in naive mice elevates Kcnj16 and produces neuropathic pain-like behaviors.\",\n      \"method\": \"Spinal nerve ligation model; N6amt1 rescue (viral overexpression); m6A methylation analysis at Kcnj16 promoter; behavioral pain assays; N6amt1 knockdown in naive mice\",\n      \"journal\": \"Pain\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — epigenetic mechanism with gain and loss of function in vivo and promoter methylation analysis, single lab\",\n      \"pmids\": [\"37624905\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Kir5.1 is essential for assembly of the basolateral 50-pS K+ channel (Kir4.2/Kir5.1 heterotetramer) in the proximal tubule: the 50-pS channel is completely absent in Kir5.1 KO mice, and Kir4.2 expression and basolateral membrane staining are significantly reduced (while Kir4.1 in DCT is increased), resulting in depolarization of the proximal tubule membrane potential.\",\n      \"method\": \"Kir5.1 knockout mice; single-channel patch-clamp; immunoblotting; immunofluorescence; membrane potential recording\",\n      \"journal\": \"American journal of physiology. Renal physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean genetic knockout with single-channel electrophysiology, immunolocalization, and membrane potential measurements providing convergent evidence\",\n      \"pmids\": [\"39745541\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Short-term (1-day) angiotensin-II-induced stimulation of NCC (via WNK4 and SPAK phosphorylation) depends on Kir4.1/Kir5.1 activity, as this effect is abolished in kidney-specific Kir4.1 KO mice. However, long-term (7-day) Ang-II can stimulate NCC by a Kir4.1/Kir5.1-independent mechanism.\",\n      \"method\": \"Kidney-specific AT1aR KO and Kir4.1 KO mice; patch-clamp; immunoblotting (pWNK4, pSPAK, pNCC, tNCC); renal clearance with thiazide\",\n      \"journal\": \"American journal of physiology. Renal physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — two genetic knockout models with electrophysiology and biochemical epistasis experiments, clear temporal dissection\",\n      \"pmids\": [\"40241495\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"Activation of basolateral calcium-sensing receptor (CaSR) in the DCT inhibits Kir4.1/Kir5.1 and depolarizes the DCT membrane via PLC-PKC pathway; CaSR agonist R-568 effect is abolished by PLC or PKC inhibitors, and elevated extracellular Ca2+ (5 mM) similarly inhibits the channel by a PKC-dependent mechanism.\",\n      \"method\": \"Cell-attached patch-clamp in isolated DCT; CaSR agonists (R-568, neomycin); PLC inhibitor; PKC inhibitor (calphostin-C); Ca2+ manipulation\",\n      \"journal\": \"American journal of physiology. Renal physiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct patch-clamp in native DCT with pharmacological pathway dissection, single lab\",\n      \"pmids\": [\"41886268\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"KCNJ16/Kir5.1 is an inwardly rectifying K+ channel subunit that cannot form functional homomeric channels under most conditions, but obligately heteromerizes with Kir4.1 (in DCT/CNT/CCD/brain) or Kir4.2 (in proximal tubule) to form pH-sensitive basolateral K+ channels; Kir5.1 confers physiological-range intracellular pH sensitivity (pKa ~7.45) on these heteromers, enabling them to function as K+/pH sensors in the DCT that couple dietary K+ and Na+ intake to NCC activity via membrane potential changes, with channel activity regulated by Nedd4-2-mediated ubiquitination (through a C-terminal TPVT motif on Kir5.1), PKC (via Gαq-coupled receptors or CaSR), PKA (via β-adrenergic signaling), calcineurin/PP2B, PIP2, oxidative stress (S-glutathionylation of Cys158 in Kir5.1's TM2), and the scaffolding protein PSD-95 (which enables homomeric Kir5.1 plasma membrane expression in neurons); in vivo, loss of Kir5.1 disrupts renal salt handling, acid-base homeostasis, blood pressure control, CO2/O2 chemoreflexes, neuronal excitability (causing audiogenic seizures), and male fertility.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"KCNJ16 encodes Kir5.1, an inwardly rectifying K+ channel subunit that does not form functional homomeric channels but obligately heteromerizes with members of the Kir4.0 subfamily (Kir4.1/KCNJ10 or Kir4.2/KCNJ15) to generate pH-sensitive basolateral K+ channels [#0, #6]. The defining functional contribution of Kir5.1 is to shift the intracellular pH sensitivity of these heteromers into the physiological range (pKa ~7.45 versus ~6 for homomeric Kir4.1), converting the channel into a K+/pH sensor, with the novel rectification and gating arising from an intersubunit interface between the cytoplasmic domains [#1, #3, #7]. In the distal convoluted tubule, Kir4.1/Kir5.1 sets the basolateral membrane potential and acts as the upstream sensor that couples dietary Na+, K+, and acid-base status to NCC activity; loss of Kir5.1 abolishes the responsiveness of the DCT to dietary Na+ and K+ and disrupts NCC regulation [#14, #20, #21, #27]. In the proximal tubule Kir5.1 is required for assembly of the Kir4.2/Kir5.1 50-pS channel that maintains membrane polarization [#32]. Channel activity is tuned by Nedd4-2-mediated ubiquitination acting through a C-terminal TPVT motif on Kir5.1, by PKC downstream of Gαq-coupled receptors and the calcium-sensing receptor, by β-adrenergic/PKA signaling, by calcineurin/PP2B, by PIP2, and by S-glutathionylation of Cys158 in TM2 during oxidative stress [#19, #34, #22, #30, #2, #15]. In the brain, Kir5.1 assembles with Kir4.1 in astrocytes in a region-specific manner and, via PSD-95, can reach the plasma membrane as a homomer [#8, #5]. Loss-of-function mutations in KCNJ16 cause a human tubulopathy comprising hypokalemia, salt wasting, disturbed acid-base homeostasis, and sensorineural deafness [#26]; in rodents Kcnj16 deletion additionally impairs CO2/O2 chemoreflexes, causes audiogenic seizures, and reduces male fertility [#23, #25, #28].\",\n  \"teleology\": [\n    {\n      \"year\": 2000,\n      \"claim\": \"Established that Kir5.1 is not an autonomous channel but a modulatory subunit that, by heteromerizing with Kir4.1, imposes physiological-range intracellular pH sensitivity on the resulting channel.\",\n      \"evidence\": \"Heterologous co-expression and voltage clamp in Xenopus oocytes with pH titration and K67M mutagenesis\",\n      \"pmids\": [\"10764726\", \"10790154\", \"10871638\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not establish the structural basis of how Kir5.1 raises the pKa\", \"Endogenous heteromer composition in native tissue not yet defined\"]\n    },\n    {\n      \"year\": 2000,\n      \"claim\": \"Resolved how Kir5.1 changes channel biophysics at the single-channel level and how PIP2 modulates pH gating, showing pH acts on open-state probability rather than conductance.\",\n      \"evidence\": \"Inside-out single-channel patch-clamp in oocytes with exogenous PIP2 and R178/K67 mutagenesis\",\n      \"pmids\": [\"10871638\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural location of the pH-sensing residues not defined\", \"PIP2 binding site only mapped to a single residue\"]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"Showed that Kir5.1's partner specificity extends to Kir4.2 and that its assembly differentially reshapes gating depending on partner, distinguishing functional heteromerization from inhibitory silencing of non-partners.\",\n      \"evidence\": \"Single-channel recording of Kir4.2/Kir5.1 and Kir2.1/Kir5.1 co-expression in oocytes\",\n      \"pmids\": [\"11306656\", \"11240146\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Physiological relevance of Kir2.1 silencing in native cells untested\", \"Stoichiometry of heteromers not determined\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Defined the selectivity rules for Kir5.1 assembly (Kir4.0 subfamily only) and identified PSD-95 as a scaffold that overcomes Kir5.1's rapid internalization to permit homomeric surface expression in neurons.\",\n      \"evidence\": \"Co-IP from brain tissue, chimera mutagenesis, and electrophysiology in HEK293T cells with PKA manipulation\",\n      \"pmids\": [\"12456399\", \"11988170\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether homomeric Kir5.1/PSD-95 channels exist physiologically in vivo unclear\", \"PKA phosphorylation site on Kir5.1 not precisely mapped\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Localized the determinants of rectification, gating, and pH sensitivity to an intersubunit interface between the cytoplasmic domains, providing a structural rationale for functional coupling in the heteromer.\",\n      \"evidence\": \"Site-directed mutagenesis of interface residues with whole-cell and excised-patch electrophysiology in oocytes\",\n      \"pmids\": [\"12923169\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No high-resolution structure of the heteromeric interface\", \"Single lab\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Mapped the in vivo expression of Kir5.1 in astrocytes and cochlear fibrocytes, revealing region-specific co-assembly with Kir4.1 versus spatial segregation, indicating context-dependent channel composition.\",\n      \"evidence\": \"Immunoprecipitation and subunit-specific immunolabeling in mouse brain and cochlear lateral wall\",\n      \"pmids\": [\"15310750\", \"14750965\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Functional consequence of regional heteromer/homomer balance untested\", \"Syntrophin role in targeting only correlative\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Identified post-translational regulatory inputs (PKC and Gαq-coupled neurotransmitter receptors) that selectively inhibit the heteromer, showing Kir5.1 confers signaling responsiveness absent from homomeric Kir4.1.\",\n      \"evidence\": \"Tandem-dimer oocyte expression with PMA, GPCR agonists, PKC inhibitors, and in vitro phosphorylation\",\n      \"pmids\": [\"17585871\", \"17559083\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"PKC phosphorylation sites not definitively mapped due to redundancy\", \"Heterologous system; native DCT/neuron validation limited\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Confirmed that Kir4.1/Kir5.1 is the predominant native basolateral K+ channel in collecting duct principal cells and is responsive to dietary salt, linking the channel to renal salt handling.\",\n      \"evidence\": \"Patch-clamp in native mouse cortical collecting duct with immunohistochemistry, qPCR, and dietary manipulation\",\n      \"pmids\": [\"18367659\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Causal upstream/downstream relationship to transporters not yet established\", \"Cell-type restriction within nephron incomplete\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Demonstrated genetically that Kir5.1 is a required determinant of neuronal pH/PCO2 chemosensitivity, moving the in vitro pH-sensor model into native neurons.\",\n      \"evidence\": \"Kcnj16 knockout mice with patch-clamp of locus coeruleus neurons under pH manipulation\",\n      \"pmids\": [\"21047793\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether residual Kir4.1 compensates incompletely characterized\", \"Link to whole-animal respiratory behavior not yet made\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Established the in vivo renal phenotype of Kir5.1 loss—hypokalemic hyperchloremic metabolic acidosis with enhanced DCT Na+ absorption—defining Kir5.1 as a pH-sensitive regulator of distal salt transport.\",\n      \"evidence\": \"Kcnj16 knockout mouse metabolic studies, DCT basolateral patch-clamp, and hydrochlorothiazide challenge\",\n      \"pmids\": [\"21633011\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism linking basolateral channel to apical NCC not yet defined\", \"Acid-base versus salt contributions not fully separated\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Identified S-glutathionylation of Cys158 in TM2 as the molecular mechanism coupling oxidative stress to selective inhibition of the heteromer.\",\n      \"evidence\": \"Whole-cell/inside-out patch-clamp in HEK cells with C158 mutagenesis, tandem dimers, and biochemical GSH assays\",\n      \"pmids\": [\"22907060\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vivo relevance of Cys158 modification untested\", \"Physiological oxidant sources not identified\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Showed that Kir5.1 modulates the functional output of disease-relevant Kir4.1 mutations, with implications for how KCNJ10 variants are assessed.\",\n      \"evidence\": \"Co-expression of KCNJ16 with KCNJ10 p.A167V in oocytes with voltage clamp and Western blot\",\n      \"pmids\": [\"24193250\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab heterologous assay\", \"In vivo consequence of suppression untested\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Identified upstream transcriptional control of Kcnj16 by HNF1β, connecting the channel to a developmental/renal transcription factor whose mutations cause kidney disease.\",\n      \"evidence\": \"ChIP-seq, luciferase promoter assay, siRNA knockdown, and renal HNF1β knockout mouse with qPCR\",\n      \"pmids\": [\"28577853\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Other transcriptional regulators not surveyed\", \"Quantitative link from transcript reduction to channel function not measured\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Demonstrated in a rat model that Kir5.1 loss causes life-threatening salt wasting and placed the channel upstream of ENaC-dependent Na+ transport via pharmacological epistasis.\",\n      \"evidence\": \"Kcnj16 knockout Dahl SS rat with collecting duct electrophysiology, IHC, dietary challenge, and benzamil/diuretic rescue\",\n      \"pmids\": [\"28931751\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism of Kir4.1 cytosolic mislocalization without Kir5.1 unclear\", \"Species-specific differences from mouse not reconciled\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Defined Nedd4-2 regulation of the channel, showing it binds the Kir5.1 C-terminal TPVT motif to ubiquitinate Kir4.1 and reduce surface expression—a Kir5.1-dependent degradative control point.\",\n      \"evidence\": \"Co-IP, GST pulldown, ubiquitination assay, T249A mutagenesis, patch-clamp, and kidney-specific Nedd4-2 KO mice\",\n      \"pmids\": [\"29897283\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Upstream signals controlling Nedd4-2 activity on this channel not defined\", \"Phosphorylation state of TPVT motif in vivo not measured\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Established the central physiological circuit: Kir4.1/Kir5.1 is the DCT sensor that translates dietary Na+ and K+ into membrane potential changes that set NCC activity, with Kir5.1 required for both Na+- and K+-sensing.\",\n      \"evidence\": \"Kir5.1 and kidney-specific Kir4.1 knockout mice with patch-clamp, immunoblotting, and renal clearance under varied diets\",\n      \"pmids\": [\"31239388\", \"30559144\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular link from membrane potential to WNK-SPAK-NCC cascade not fully resolved here\", \"Relative weighting of K+ versus Na+ signals unclear\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Identified hormonal (β-adrenergic/PKA) activation of the DCT channel as an NCC-regulatory input and demonstrated whole-animal chemoreflex deficits, broadening Kir5.1's physiological reach to blood pressure and respiratory control.\",\n      \"evidence\": \"DCT patch-clamp with PKA pharmacology and Kir4.1-KO mice; plethysmography and blood gas in Kcnj16-KO rats\",\n      \"pmids\": [\"30571558\", \"30605394\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"PKA phosphorylation target on the channel not mapped in vivo\", \"Integration of renal and respiratory phenotypes incomplete\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Confirmed by double-knockout epistasis that Nedd4-2 regulates NCC partly through Kir4.1/Kir5.1, integrating ubiquitin-mediated control into the salt-handling circuit.\",\n      \"evidence\": \"Kidney-specific Nedd4-2 KO, Kir4.1 KO, and double-KO mice with electrophysiology and biochemistry\",\n      \"pmids\": [\"32295826\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Nedd4-2 effects on NCC independent of the channel not fully quantified\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Extended the channel's roles to neuronal excitability and reproduction, and—critically—established KCNJ16 mutations as the cause of a human tubulopathy with deafness through loss of heteromeric channel function.\",\n      \"evidence\": \"Kcnj16-KO rat EEG/seizure and KO-mouse fertility studies; human whole-exome sequencing with oocyte functional assays of patient mutations\",\n      \"pmids\": [\"33232300\", \"34205849\", \"33811157\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Cellular site of Kir5.1 action in seizures and sperm not defined\", \"Genotype-phenotype correlation across patient mutations incomplete\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Resolved a novel intrinsic, cation-independent inward rectification mechanism driven by voltage-dependent K+-flux gating, refining the biophysical model of the heteromer.\",\n      \"evidence\": \"Excised inside-out patch-clamp in HEK cells with removal of blocking cations, PIP2, and mutagenesis\",\n      \"pmids\": [\"33822868\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural gate underlying flux-dependent gating not identified\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Added calcineurin/PP2B (via FKBP-12/Src) and CaSR-PLC-PKC as regulatory inputs and revealed an N6amt1/m6A epigenetic pathway controlling Kcnj16 in neuropathic pain, expanding the regulatory and pathophysiological repertoire.\",\n      \"evidence\": \"DCT patch-clamp with FK506/CsA and FKBP-12/Kir4.1 KO mice; spinal nerve ligation model with N6amt1 manipulation and promoter m6A analysis\",\n      \"pmids\": [\"36821372\", \"37624905\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct molecular target of PP2B on the channel not identified\", \"m6A/Kcnj16 pain mechanism from single lab\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Demonstrated that Kir5.1 is required for assembly and basolateral targeting of the proximal-tubule Kir4.2/Kir5.1 50-pS channel and dissected the temporal dependence of angiotensin-II NCC stimulation on the channel.\",\n      \"evidence\": \"Kir5.1-KO mice with single-channel patch-clamp and membrane potential recording; AT1aR-KO and Kir4.1-KO mice with WNK4/SPAK/NCC phosphorylation epistasis\",\n      \"pmids\": [\"39745541\", \"40241495\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism of the long-term, channel-independent Ang-II effect on NCC unknown\", \"Proximal-tubule physiological consequences of channel loss incompletely defined\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"A high-resolution structure of the Kir4.x/Kir5.1 heteromer and the precise molecular path from basolateral membrane potential to WNK-SPAK-NCC phosphorylation remain to be defined.\",\n      \"evidence\": null,\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No experimental structure of the heteromeric channel\", \"Membrane-potential-to-WNK signaling step not molecularly resolved\", \"Cellular substrate of seizure and fertility phenotypes unmapped\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0005215\", \"supporting_discovery_ids\": [0, 1, 12, 29]},\n      {\"term_id\": \"GO:0140299\", \"supporting_discovery_ids\": [1, 13, 14]},\n      {\"term_id\": \"GO:0008289\", \"supporting_discovery_ids\": [2, 29]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [5, 8, 12, 18, 32]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [5, 18, 32]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-382551\", \"supporting_discovery_ids\": [14, 20, 21, 27]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [11, 22, 30, 34]},\n      {\"term_id\": \"R-HSA-112316\", \"supporting_discovery_ids\": [13, 25]}\n    ],\n    \"complexes\": [\n      \"Kir4.1/Kir5.1 heterotetramer\",\n      \"Kir4.2/Kir5.1 heterotetramer\"\n    ],\n    \"partners\": [\n      \"KCNJ10\",\n      \"KCNJ15\",\n      \"PSD-95\",\n      \"NEDD4L\",\n      \"syntrophin\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":7,"faith_total":7,"faith_pct":100.0}}