{"gene":"KCNB2","run_date":"2026-06-10T01:55:23","timeline":{"discoveries":[{"year":1996,"finding":"A novel beta subunit, mKvbeta4, specifically associates with Kv2.2 (CDRK/KCNB2) but not the closely related Kv2.1, enhancing Kv2.2 expression level up to 6-fold at the plasma membrane without changing its elementary conductance or kinetics. The C-terminal end of Kv2.2 is essential for mKvbeta4 sensitivity. The effect is proposed to be chaperone-like, permitting integration of more channels at the plasma membrane.","method":"Xenopus oocyte co-expression, chimeric channel analysis between Kv2.1 and Kv2.2, co-localization of transcripts in brain","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-expression functional assay plus chimeric subunit mapping, single lab, two orthogonal methods","pmids":["8824288"],"is_preprint":false},{"year":1999,"finding":"Angiotensin II, acting through AT1 receptors, inhibits Kv2.2 currents in hypothalamic/brainstem neurons. Co-expression of Kv2.2 and the AT1 receptor in Xenopus oocytes confirmed Ang II-induced inhibition of Kv2.2 current. This inhibition contributes to increased neuronal firing rate relevant to cardiovascular regulation.","method":"Patch-clamp electrophysiology of neuronal cocultures, Xenopus oocyte co-expression, RT-PCR, Western blot, pharmacological dissection","journal":"Circulation research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — heterologous reconstitution plus native neuronal electrophysiology, single lab, two orthogonal methods","pmids":["10024310"],"is_preprint":false},{"year":2004,"finding":"The proximal carboxyl terminus (proxC domain) of Kv2.2 mediates a developmental, subunit-specific regulation of channel density in Xenopus spinal neurons. Kv2.2 overexpression increases IKv density in young but not mature neurons; chimeric Kv2 subunits lacking the proxC domain of Kv2.2 rescued current density increase in mature neurons, identifying proxC as responsible for restricting functional expression at mature stages.","method":"Chimeric Kv2.1/Kv2.2 subunit expression in Xenopus embryos, heterologous expression in oocytes, in vivo current measurements","journal":"Journal of neurophysiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — chimeric subunit domain mapping with in vivo and heterologous functional assays, single lab, two orthogonal methods","pmids":["15306626"],"is_preprint":false},{"year":2006,"finding":"Kv2.2 interacts with syntaxin 1A (a t-SNARE) but, unlike Kv2.1, does not interact with the syntaxin 1A/SNAP-25 complex and is therefore insensitive to the assembly/disassembly state of this SNARE complex. This distinct regulation is attributed to differences in the C-termini of Kv2.1 and Kv2.2. Immunohistochemistry showed Kv2.2 is the dominant Kv channel in pancreatic alpha and delta cells (not beta cells), suggesting SNARE-Kv2.2 interactions regulate glucagon and somatostatin secretion.","method":"Two-electrode voltage clamp in Xenopus oocytes, immunohistochemistry, comparative functional analysis of Kv2.1 vs Kv2.2 with syntaxin 1A and SNAP-25 co-expression","journal":"Molecular pharmacology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — heterologous reconstitution with functional readout plus immunolocalization, single lab, two orthogonal methods","pmids":["16754785"],"is_preprint":false},{"year":2008,"finding":"Kv2.2 channels are highly expressed at the axon initial segment of MNTB neurons. Hodgkin-Huxley modelling and current-clamp recordings demonstrated that Kv2.2 plays a minor role during single action potentials but hyperpolarizes interspike potentials during repetitive firing, thereby assisting recovery of voltage-gated sodium channels from inactivation and maintaining action potential amplitude at high frequencies.","method":"Quantitative RT-PCR, immunofluorescence confocal imaging, Western blot (including Kv2.2 knockout tissue), patch-clamp electrophysiology, Hodgkin-Huxley modelling","journal":"The Journal of physiology","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (KO confirmation, localization, electrophysiology, modelling), replicated across approaches in single rigorous study","pmids":["18511484"],"is_preprint":false},{"year":2008,"finding":"In Xenopus laevis neurons, Kv2.2 protein localizes to long axonal-like processes and colocalizes with alpha-tubulin intracellularly, contrasting with Kv2.1 which is somatodendritic. This differential subcellular localization supports distinct functional roles for the two paralogs during development.","method":"Antibody development and immunodetection in Xenopus embryos and cultured neurons, Western blot specificity confirmation (Kv2.2 vs Kv2.1), confocal imaging","journal":"The Journal of comparative neurology","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — immunolocalization with specificity controls and comparison to Kv2.1, single lab","pmids":["18680201"],"is_preprint":false},{"year":2010,"finding":"Kv2.2 is abundantly expressed in a large subpopulation (~60%) of GABAergic neurons in the magnocellular preoptic nucleus (MCPO) and horizontal limb of the diagonal band of Broca (HDB) of the basal forebrain, identified using specific immunolabeling and GFP-knockin mice expressing GFP in GABAergic neurons.","method":"Immunolabeling, GFP-knockin reporter mice (GAD67-GFP), confocal microscopy","journal":"The Journal of comparative neurology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — cell-type-specific localization with genetic reporter mouse and immunolabeling, single lab","pmids":["20853508"],"is_preprint":false},{"year":2012,"finding":"Kv2.2 specifically regulates somatostatin release from pancreatic delta-cells. shRNA-mediated knockdown of Kv2.2 in mouse islets selectively enhanced somatostatin secretion without affecting insulin secretion. Pharmacological inhibition with GxTX-1E (which blocks both Kv2.1 and Kv2.2) also enhanced somatostatin release, including in Kv2.1 knockout mice, confirming a Kv2.2-dependent mechanism in delta-cells.","method":"Adenovirus-delivered shRNA knockdown, selective peptide (GxTX-1E) and small molecule (RY796) inhibitors, Kv2.1 knockout mice, isolated islet secretion assays, perfused pancreata","journal":"The Journal of pharmacology and experimental therapeutics","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic knockdown plus pharmacology plus KO mouse model, multiple orthogonal approaches in a single rigorous study","pmids":["23161216"],"is_preprint":false},{"year":2013,"finding":"Kv2.2 regulates neuronal excitability in VNTB neurons of the medial olivocochlear system by maintaining short action potentials and enabling high-frequency firing. Viral dominant-negative Kv2.2 gene transfer suppressed outward K+ currents, increased AP half-width, and reduced repetitive firing. Kv2.2 knockout mice showed the same AP duration increase and were more susceptible to noise-induced hearing loss.","method":"Viral gene transfer of dominant-negative Kv2.2, Kv2.2 knockout mice, patch-clamp electrophysiology, in vivo auditory brainstem response recordings","journal":"The Journal of neuroscience","confidence":"High","confidence_rationale":"Tier 2 / Strong — dominant-negative plus germline KO with electrophysiology and in vivo functional readout, multiple orthogonal methods","pmids":["23699522"],"is_preprint":false},{"year":2013,"finding":"miR-1 targets KCNB2 (and KCNE1) directly, as confirmed by luciferase activity assay. Upregulation of miR-1 during atrial tachypacing downregulates KCNB2, contributing to shortening of atrial effective refractory period and increased IKs.","method":"Luciferase reporter assay (direct target confirmation), lentiviral miR-1 overexpression, siRNA knockdown, patch-clamp, in vivo AERP measurement","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct luciferase validation of miR-1 targeting KCNB2 plus functional electrophysiological readout, single lab","pmids":["24386485"],"is_preprint":false},{"year":2013,"finding":"Pyruvate-isocitrate cycling (via cytosolic NADP-dependent isocitrate dehydrogenase, ICDc) regulates Kv2.2 expression in islet beta-cells. Immunoprecipitation demonstrated physical interaction between Kv2.1 and Kv2.2. Co-overexpression of Kv2.1 and Kv2.2 reduced outward K+ current compared with Kv2.1 alone, supporting Kv2.2 as a negative modulator of Kv channel activity. Kv2.2 knockdown rescued the GSIS defect caused by ICDc knockdown.","method":"siRNA knockdown, adenoviral re-expression, co-immunoprecipitation, patch-clamp electrophysiology, selective inhibitor stromatoxin1","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal co-IP for Kv2.1/Kv2.2 interaction plus functional epistasis rescue, single lab, two orthogonal methods","pmids":["23788641"],"is_preprint":false},{"year":2013,"finding":"Kv2.2-expressing GABAergic neurons in the basal forebrain are preferentially active during waking (c-Fos labeling) and regulate the sleep-wake cycle. Kv2.2 knockout mice exhibited longer consolidated wake bouts and reduced delta-frequency EEG activity during NREM sleep. Basal forebrain GABAergic neurons showed augmented c-Fos expression in Kv2.2 knockout mice.","method":"Kv2.2 knockout mice, EEG/EMG sleep recordings, c-Fos immunostaining, sleep deprivation protocol","journal":"Sleep","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — germline KO with defined physiological phenotype and neuronal activity marker, single lab","pmids":["24293758"],"is_preprint":false},{"year":2021,"finding":"Protein kinase C (PKC) phosphorylates Kv2.2 at residues S481 and S488, inhibiting Kv2.2 currents and altering steady-state activation. Point mutations at S481 and S488 abolished PKC-dependent modulation. In cortical layer II pyramidal neurons, PKC activation similarly inhibited native Kv2.2 channels and reduced action potential firing frequency.","method":"PKC activation in HEK293 cells expressing Kv2.2, point mutagenesis (S481A, S488A), phospho-specific antibodies, patch-clamp in native cortical neurons","journal":"Neuroscience bulletin","confidence":"High","confidence_rationale":"Tier 1 / Moderate — site-directed mutagenesis identifying phosphorylation sites plus functional validation in native neurons, two orthogonal methods, single lab","pmids":["34542799"],"is_preprint":false},{"year":2021,"finding":"An inter-subunit hydrogen bond formed by W366 and Y376 (Kv2.1 numbering; conserved in Kv2.2) is essential for K+ conductance. Mutations disrupting this H-bond caused complete loss of K+ conductance in Kv2.1, Kv2.2, and Kv1.2 channels, differing from the Shaker inactivation mechanism.","method":"Point mutagenesis, patch-clamp recording in cells expressing Kv2.2 and related channels","journal":"Membranes","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — mutagenesis with functional electrophysiology, single lab, single method","pmids":["33803465"],"is_preprint":false},{"year":2023,"finding":"Cortisol (glucocorticoid) rapidly increases Kv2.2 currents by increasing single-channel open probability through activation of a membrane-associated glucocorticoid receptor, independent of genomic signaling. This effect is mediated through the ERK1/2 kinase pathway (blocked by U0126). A membrane-impermeable glucocorticoid receptor agonist (BSA-dexamethasone) mimicked the effect. In cortical pyramidal neurons and calyx of Held synapses, cortisol suppressed AP firing frequency and increased activity-dependent synaptic depression via Kv2.2 activation.","method":"Single-channel patch-clamp in HEK293 cells expressing Kv2.2, pharmacological inhibition (U0126, EP receptor antagonists), membrane-impermeable agonist, patch-clamp in acute brain slices","journal":"Neurobiology of stress","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — single-channel recordings plus pathway inhibition plus native neuron recordings, single lab, multiple orthogonal methods","pmids":["38075025"],"is_preprint":false},{"year":2023,"finding":"EZH2-mediated H3K27me3 histone trimethylation at the KCNB2 promoter (CpG island and upstream region) represses KCNB2 expression in bladder smooth muscle cells during obstruction. EZH2 inhibition (UNC1999) restored KCNB2 expression and partially restored smooth muscle cell phenotype. Matrix conditions regulate EZH2 and H3K27me3 levels affecting KCNB2 expression.","method":"ChIP/PCR for H3K27me3 at KCNB2 promoter in obstruction tissue, EZH2 inhibitor treatment, siRNA knockdown of KCNB2, Western blotting, immunostaining","journal":"American journal of clinical and experimental urology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP at the KCNB2 promoter plus pharmacological and siRNA functional validation, single lab","pmids":["37645613"],"is_preprint":false},{"year":2025,"finding":"PGE2 inhibits Kv2.2 channels via PKA-dependent phosphorylation at residue S448, acting through EP2/4 receptors. Point mutation of S448 blocked the PKA-dependent PGE2 inhibition. In INS-1 beta-cells, PGE2 inhibited voltage-gated K+ currents and electrical activity through EP2/4 receptors and Kv2.2. Kcnb2 knockout mice showed abrogated PGE2-induced glucose intolerance, and Kv2.2 knockdown alleviated PGE2 inhibition of GSIS.","method":"HEK293T overexpression, point mutagenesis (S448A), PKA pathway manipulation, EP receptor antagonists/agonists, INS-1 beta-cell electrophysiology, Kcnb2 knockout mice, glucose tolerance testing, islet GSIS assays","journal":"eLife","confidence":"High","confidence_rationale":"Tier 1 / Strong — site-directed mutagenesis identifying phosphorylation site, plus KO mouse phenotyping, plus native cell electrophysiology, multiple orthogonal methods in single study","pmids":["40028769"],"is_preprint":false},{"year":2025,"finding":"Kv2.2 co-assembles with the electrically-silent subunit Kv6.4 and co-clusters with Kv2.1 at endoplasmic reticulum-plasma membrane (ER-PM) junctions beneath C-bouton synapses in spinal motor neurons. In Kv2.2 knockout mice, Kv6.4 clustering at ER-PM junctions is moderately reduced, indicating that Kv2.2 contributes to the localization and expression of Kv6.4 through co-assembly. AMIGO-1 auxiliary subunit clustering is also moderately reduced in Kv2.2 KO mice.","method":"Immunofluorescence co-localization, Kv2.1 S590A mutant mice, Kv2.1 and Kv2.2 knockout mice, confocal and super-resolution microscopy","journal":"bioRxiv","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-localization with multiple KO/mutant mouse models, single lab, preprint not yet peer-reviewed","pmids":["bio_10.1101_2025.06.04.657913"],"is_preprint":true}],"current_model":"KCNB2 (Kv2.2) encodes a voltage-gated delayed rectifier K+ channel that localizes preferentially to axon initial segments and ER-PM junctions, forms heteromeric complexes with Kv2.1 and electrically-silent KvS subunits (Kv6.4), and is regulated by multiple post-translational modifications including PKC-mediated phosphorylation at S481/S488 (inhibitory), PKA-mediated phosphorylation at S448 downstream of PGE2/EP2-4 receptor signaling (inhibitory), and ERK1/2-mediated activation downstream of membrane glucocorticoid receptor; its activity is also modulated by the beta subunit mKvbeta4 (which enhances surface expression via the Kv2.2 C-terminus) and by t-SNAREs (syntaxin 1A alone, but not the syntaxin/SNAP-25 complex); in neurons it maintains high-frequency action potential firing by hyperpolarizing interspike potentials and enabling Nav channel recovery, and in pancreatic delta-cells it specifically controls somatostatin secretion while in beta-cells it modulates GSIS through its interaction with Kv2.1 and the EP2/4-Kv2.2-PKA pathway."},"narrative":{"mechanistic_narrative":"KCNB2 encodes Kv2.2, a voltage-gated delayed rectifier K+ channel that tunes neuronal excitability and endocrine secretion by shaping repolarization during sustained electrical activity [PMID:18511484, PMID:23699522]. In auditory brainstem neurons it concentrates at the axon initial segment, where it contributes little to single spikes but hyperpolarizes interspike potentials during repetitive firing, promoting recovery of voltage-gated Na+ channels from inactivation and thereby sustaining high-frequency action potential firing [PMID:18511484, PMID:23699522]. Its functional output is set by subunit context: Kv2.2 physically interacts with Kv2.1 and acts as a negative modulator of the resulting heteromeric current [PMID:23788641], co-assembles with the electrically-silent KvS subunit Kv6.4 at ER-PM junctions and supports Kv6.4 clustering [PMID:bio_10.1101_2025.06.04.657913], and binds the t-SNARE syntaxin 1A in a manner distinct from Kv2.1 [PMID:16754785], while the accessory subunit mKvbeta4 selectively boosts Kv2.2 surface expression through its C-terminus [PMID:8824288]. Channel activity is further controlled by post-translational modification, being inhibited by PKC phosphorylation at S481/S488 [PMID:34542799] and by PKA phosphorylation at S448 downstream of PGE2/EP2-4 signaling [PMID:40028769], yet activated by a non-genomic membrane glucocorticoid receptor pathway acting through ERK1/2 [PMID:38075025]. Beyond neurons, Kv2.2 governs hormone secretion in pancreatic islets, selectively restraining somatostatin release from delta-cells [PMID:23161216] and modulating glucose-stimulated insulin secretion via its interaction with Kv2.1 and the EP2/4-PKA axis [PMID:23788641, PMID:40028769]. KCNB2 expression is itself regulated transcriptionally and post-transcriptionally, being a direct target of miR-1 [PMID:24386485] and repressed by EZH2-mediated H3K27me3 at its promoter [PMID:37645613].","teleology":[{"year":1996,"claim":"Established that Kv2.2 surface expression is governed by a dedicated accessory subunit, distinguishing its regulation from the paralog Kv2.1.","evidence":"Xenopus oocyte co-expression with mKvbeta4 and Kv2.1/Kv2.2 chimeric mapping","pmids":["8824288"],"confidence":"Medium","gaps":["Chaperone-like mechanism inferred but not biochemically resolved","Physiological relevance in native neurons not tested"]},{"year":1999,"claim":"Showed Kv2.2 is a downstream effector of GPCR signaling, linking AT1 receptor activation to suppression of K+ current and increased neuronal firing.","evidence":"Patch-clamp of neuronal cocultures plus AT1/Kv2.2 co-expression in oocytes","pmids":["10024310"],"confidence":"Medium","gaps":["Molecular mechanism of inhibition not defined","No phosphorylation site identified"]},{"year":2004,"claim":"Mapped a proximal C-terminal domain controlling developmental, stage-specific restriction of Kv2.2 functional density.","evidence":"Chimeric Kv2.1/Kv2.2 subunit expression in Xenopus embryos and oocytes","pmids":["15306626"],"confidence":"Medium","gaps":["Binding partners mediating proxC restriction unknown","Restricted to amphibian development"]},{"year":2006,"claim":"Defined a paralog-specific SNARE interaction, showing Kv2.2 binds syntaxin 1A but is insensitive to the syntaxin/SNAP-25 complex, implying a distinct role in islet hormone secretion.","evidence":"Two-electrode voltage clamp with syntaxin 1A/SNAP-25 co-expression plus islet immunohistochemistry","pmids":["16754785"],"confidence":"Medium","gaps":["Direct effect on glucagon/somatostatin secretion not measured here","C-terminal determinant of selectivity not mutationally mapped"]},{"year":2008,"claim":"Resolved the core neuronal function of Kv2.2: AIS-localized channels hyperpolarize interspike potentials to enable Nav recovery and high-frequency firing.","evidence":"RT-PCR, immunofluorescence, KO tissue Western blot, patch-clamp, and Hodgkin-Huxley modelling in MNTB neurons","pmids":["18511484"],"confidence":"High","gaps":["Did not address heteromerization with Kv2.1 in this context","AIS targeting mechanism not defined"]},{"year":2008,"claim":"Demonstrated axonal localization of Kv2.2 distinct from somatodendritic Kv2.1, supporting divergent paralog roles.","evidence":"Specificity-controlled immunodetection and confocal imaging in Xenopus neurons","pmids":["18680201"],"confidence":"Medium","gaps":["Trafficking determinants not identified","Tubulin colocalization mechanism unresolved"]},{"year":2010,"claim":"Identified a defined Kv2.2-expressing cell population, GABAergic basal forebrain neurons, anchoring later circuit-level studies.","evidence":"Immunolabeling combined with GAD67-GFP knockin reporter mice","pmids":["20853508"],"confidence":"Medium","gaps":["Functional consequence in these neurons not tested here"]},{"year":2012,"claim":"Established a non-redundant endocrine role: Kv2.2 selectively controls somatostatin secretion from pancreatic delta-cells independent of Kv2.1.","evidence":"shRNA knockdown, GxTX-1E/RY796 pharmacology, and Kv2.1 KO islet/pancreas secretion assays","pmids":["23161216"],"confidence":"High","gaps":["Coupling between channel activity and somatostatin exocytosis not mechanistically dissected"]},{"year":2013,"claim":"Connected Kv2.2 to auditory function, showing it maintains short APs and high-frequency firing and protects against noise-induced hearing loss.","evidence":"Dominant-negative viral transfer, Kv2.2 KO mice, patch-clamp, and auditory brainstem responses","pmids":["23699522"],"confidence":"High","gaps":["Subunit composition of native VNTB currents not defined"]},{"year":2013,"claim":"Showed Kv2.2 is a direct miR-1 target, linking microRNA regulation of KCNB2 to atrial electrical remodeling.","evidence":"Luciferase reporter assay plus miR-1 overexpression/knockdown and electrophysiology","pmids":["24386485"],"confidence":"Medium","gaps":["Cardiac Kv2.2 channel function not directly recorded","Relative contribution versus KCNE1 not separated"]},{"year":2013,"claim":"Demonstrated Kv2.2 physically interacts with Kv2.1 and negatively modulates the heteromeric current, integrating it into beta-cell metabolic control of insulin secretion.","evidence":"Co-immunoprecipitation, co-overexpression patch-clamp, and ICDc knockdown/rescue epistasis in islet beta-cells","pmids":["23788641"],"confidence":"Medium","gaps":["Stoichiometry of Kv2.1/Kv2.2 heteromers undefined","Structural basis of negative modulation unknown"]},{"year":2013,"claim":"Linked Kv2.2 to behavioral physiology by showing its loss alters sleep-wake architecture via basal forebrain GABAergic neurons.","evidence":"Kv2.2 KO mice with EEG/EMG recordings and c-Fos activity mapping","pmids":["24293758"],"confidence":"Medium","gaps":["Cell-autonomous channel contribution not isolated from network effects"]},{"year":2021,"claim":"Identified PKC phosphorylation sites S481/S488 as an inhibitory switch on Kv2.2 controlling cortical neuron firing.","evidence":"PKC activation in HEK293, S481A/S488A mutagenesis, phospho-antibodies, and native cortical neuron patch-clamp","pmids":["34542799"],"confidence":"High","gaps":["Upstream receptor coupling to PKC not specified","Interaction with other phospho-regulation not tested"]},{"year":2021,"claim":"Defined a conserved inter-subunit W366-Y376 hydrogen bond required for K+ conductance, a structural determinant distinct from Shaker inactivation.","evidence":"Point mutagenesis and patch-clamp across Kv2.1, Kv2.2, and Kv1.2","pmids":["33803465"],"confidence":"Medium","gaps":["No structural model of the bonded state","Single method, functional inference only"]},{"year":2023,"claim":"Revealed a rapid non-genomic glucocorticoid pathway that activates Kv2.2 via a membrane GR and ERK1/2, modulating neuronal firing and synaptic depression.","evidence":"Single-channel patch-clamp in HEK293, U0126 inhibition, membrane-impermeable agonist, and brain slice recordings","pmids":["38075025"],"confidence":"Medium","gaps":["Direct ERK1/2 phosphorylation site on Kv2.2 not mapped","Membrane GR identity not molecularly defined"]},{"year":2023,"claim":"Established epigenetic repression of KCNB2 by EZH2-mediated H3K27me3, linking matrix conditions to channel downregulation in bladder smooth muscle.","evidence":"ChIP for H3K27me3 at the KCNB2 promoter, EZH2 inhibition, and KCNB2 siRNA","pmids":["37645613"],"confidence":"Medium","gaps":["Smooth muscle Kv2.2 channel function not electrophysiologically characterized","Direct EZH2-KCNB2 causality versus broader program not fully separated"]},{"year":2025,"claim":"Identified PKA phosphorylation at S448 as the molecular basis for PGE2/EP2-4 inhibition of Kv2.2, with in vivo consequences for glucose homeostasis.","evidence":"S448A mutagenesis, EP receptor pharmacology, INS-1 electrophysiology, and Kcnb2 KO glucose tolerance/GSIS","pmids":["40028769"],"confidence":"High","gaps":["Cell-type specificity of the EP2/4-PKA-Kv2.2 axis beyond beta-cells not resolved"]},{"year":2025,"claim":"Showed Kv2.2 co-assembles with Kv6.4 and clusters with Kv2.1 at ER-PM junctions, supporting localization of silent subunits and auxiliary AMIGO-1.","evidence":"Immunofluorescence colocalization with Kv2.1 S590A and Kv2.1/Kv2.2 KO mice plus super-resolution microscopy (preprint)","pmids":["bio_10.1101_2025.06.04.657913"],"confidence":"Medium","gaps":["Functional output of Kv2.2/Kv6.4 heteromers not recorded","Preprint, not yet peer-reviewed"]},{"year":null,"claim":"How the multiple regulatory inputs (PKC, PKA, ERK1/2, subunit composition) are integrated to set Kv2.2 output in a given cell type, and the structural basis of its negative modulation of Kv2.1, remain unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No integrated model of competing phospho-regulation","Heteromer structure and stoichiometry undefined","Native channel composition across neuronal and endocrine cell types incompletely mapped"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0005215","term_label":"transporter activity","supporting_discovery_ids":[4,8,13]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[0,4,17]},{"term_id":"GO:0005783","term_label":"endoplasmic reticulum","supporting_discovery_ids":[17]},{"term_id":"GO:0005856","term_label":"cytoskeleton","supporting_discovery_ids":[5]}],"pathway":[{"term_id":"R-HSA-112316","term_label":"Neuronal System","supporting_discovery_ids":[4,8]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[1,14,16]}],"complexes":["Kv2.1/Kv2.2 heteromeric channel","Kv2.2/Kv6.4 heteromeric channel","ER-PM junction Kv2 cluster"],"partners":["KCNB1","KCNG4","STX1A","KCNAB4","AMIGO1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q92953","full_name":"Potassium voltage-gated channel subfamily B member 2","aliases":["Voltage-gated potassium channel subunit Kv2.2"],"length_aa":911,"mass_kda":102.6,"function":"Voltage-gated potassium channel that mediates transmembrane potassium transport in excitable membranes, primarily in the brain and smooth muscle cells. Channels open or close in response to the voltage difference across the membrane, letting potassium ions pass in accordance with their electrochemical gradient. Homotetrameric channels mediate a delayed-rectifier voltage-dependent outward potassium current that display rapid activation and slow inactivation in response to membrane depolarization. Can form functional homotetrameric and heterotetrameric channels that contain variable proportions of KCNB1; channel properties depend on the type of alpha subunits that are part of the channel. Can also form functional heterotetrameric channels with other alpha subunits that are non-conducting when expressed alone, such as KCNS1 and KCNS2, creating a functionally diverse range of channel complexes. In vivo, membranes probably contain a mixture of heteromeric potassium channel complexes, making it difficult to assign currents observed in intact tissues to any particular potassium channel family member. Contributes to the delayed-rectifier voltage-gated potassium current in cortical pyramidal neurons and smooth muscle cells","subcellular_location":"Cell membrane; Perikaryon; Cell projection, dendrite","url":"https://www.uniprot.org/uniprotkb/Q92953/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/KCNB2","classification":"Not Classified","n_dependent_lines":0,"n_total_lines":1208,"dependency_fraction":0.0},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/KCNB2","total_profiled":1310},"omim":[{"mim_id":"613382","title":"BRACHYDACTYLY, TYPE E2; BDE2","url":"https://www.omim.org/entry/613382"},{"mim_id":"608164","title":"POTASSIUM CHANNEL, VOLTAGE-GATED, SUBFAMILY V, MEMBER 1; KCNV1","url":"https://www.omim.org/entry/608164"},{"mim_id":"607738","title":"POTASSIUM CHANNEL, VOLTAGE-GATED, SHAB-RELATED SUBFAMILY, MEMBER 2; KCNB2","url":"https://www.omim.org/entry/607738"},{"mim_id":"168470","title":"PARATHYROID HORMONE-LIKE HORMONE; PTHLH","url":"https://www.omim.org/entry/168470"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Plasma membrane","reliability":"Approved"},{"location":"Nucleoli","reliability":"Additional"},{"location":"Midbody","reliability":"Additional"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in some","driving_tissues":[{"tissue":"brain","ntpm":2.0},{"tissue":"lymphoid tissue","ntpm":2.2},{"tissue":"retina","ntpm":4.2}],"url":"https://www.proteinatlas.org/search/KCNB2"},"hgnc":{"alias_symbol":["Kv2.2"],"prev_symbol":[]},"alphafold":{"accession":"Q92953","domains":[{"cath_id":"3.30.710.10","chopping":"25-132","consensus_level":"medium","plddt":91.6538,"start":25,"end":132},{"cath_id":"1.20.120,1.20.120","chopping":"166-317","consensus_level":"high","plddt":86.8161,"start":166,"end":317},{"cath_id":"1.10.287.70","chopping":"330-439","consensus_level":"high","plddt":92.4173,"start":330,"end":439}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q92953","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q92953-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q92953-F1-predicted_aligned_error_v6.png","plddt_mean":60.5},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=KCNB2","jax_strain_url":"https://www.jax.org/strain/search?query=KCNB2"},"sequence":{"accession":"Q92953","fasta_url":"https://rest.uniprot.org/uniprotkb/Q92953.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q92953/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q92953"}},"corpus_meta":[{"pmid":"18511484","id":"PMC_18511484","title":"Initial segment Kv2.2 channels mediate a slow delayed rectifier and maintain high frequency action potential firing in medial nucleus of the trapezoid body neurons.","date":"2008","source":"The Journal of physiology","url":"https://pubmed.ncbi.nlm.nih.gov/18511484","citation_count":99,"is_preprint":false},{"pmid":"8824288","id":"PMC_8824288","title":"A new K+ channel beta subunit to specifically enhance Kv2.2 (CDRK) expression.","date":"1996","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/8824288","citation_count":84,"is_preprint":false},{"pmid":"24386485","id":"PMC_24386485","title":"MicroRNA-1 accelerates the shortening of atrial effective refractory period by regulating KCNE1 and KCNB2 expression: an atrial tachypacing rabbit model.","date":"2013","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/24386485","citation_count":70,"is_preprint":false},{"pmid":"23161216","id":"PMC_23161216","title":"The role of voltage-gated potassium channels Kv2.1 and Kv2.2 in the regulation of insulin and somatostatin release from pancreatic islets.","date":"2012","source":"The Journal of pharmacology and experimental therapeutics","url":"https://pubmed.ncbi.nlm.nih.gov/23161216","citation_count":61,"is_preprint":false},{"pmid":"20853508","id":"PMC_20853508","title":"Immunolocalization of the voltage-gated potassium channel Kv2.2 in GABAergic neurons in the basal forebrain of rats and mice.","date":"2010","source":"The Journal of comparative neurology","url":"https://pubmed.ncbi.nlm.nih.gov/20853508","citation_count":36,"is_preprint":false},{"pmid":"10024310","id":"PMC_10024310","title":"Angiotensin II type 1 receptor-mediated inhibition of K+ channel subunit kv2.2 in brain stem and hypothalamic neurons.","date":"1999","source":"Circulation research","url":"https://pubmed.ncbi.nlm.nih.gov/10024310","citation_count":32,"is_preprint":false},{"pmid":"23699522","id":"PMC_23699522","title":"Protection from noise-induced hearing loss by Kv2.2 potassium currents in the central medial olivocochlear system.","date":"2013","source":"The Journal of neuroscience : the official journal of the Society for Neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/23699522","citation_count":30,"is_preprint":false},{"pmid":"24293758","id":"PMC_24293758","title":"Kv2.2: a novel molecular target to study the role of basal forebrain GABAergic neurons in the sleep-wake cycle.","date":"2013","source":"Sleep","url":"https://pubmed.ncbi.nlm.nih.gov/24293758","citation_count":23,"is_preprint":false},{"pmid":"23788641","id":"PMC_23788641","title":"Control of voltage-gated potassium channel Kv2.2 expression by pyruvate-isocitrate cycling regulates glucose-stimulated insulin secretion.","date":"2013","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/23788641","citation_count":22,"is_preprint":false},{"pmid":"16754785","id":"PMC_16754785","title":"Target soluble N-ethylmaleimide-sensitive factor attachment protein receptors (t-SNAREs) differently regulate activation and inactivation gating of Kv2.2 and Kv2.1: Implications on pancreatic islet cell Kv channels.","date":"2006","source":"Molecular pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/16754785","citation_count":17,"is_preprint":false},{"pmid":"30151916","id":"PMC_30151916","title":"Fañanas cells-the forgotten cerebellar glia cell type: Immunocytochemistry reveals two potassium channel-related polypeptides, Kv2.2 and Calsenilin (KChIP3) as potential marker proteins.","date":"2018","source":"Glia","url":"https://pubmed.ncbi.nlm.nih.gov/30151916","citation_count":13,"is_preprint":false},{"pmid":"34542799","id":"PMC_34542799","title":"Protein Kinase C Controls the Excitability of Cortical Pyramidal Neurons by Regulating Kv2.2 Channel Activity.","date":"2021","source":"Neuroscience bulletin","url":"https://pubmed.ncbi.nlm.nih.gov/34542799","citation_count":11,"is_preprint":false},{"pmid":"27033450","id":"PMC_27033450","title":"The contribution of Kv2.2-mediated currents decreases during the postnatal development of mouse dorsal root ganglion neurons.","date":"2016","source":"Physiological reports","url":"https://pubmed.ncbi.nlm.nih.gov/27033450","citation_count":10,"is_preprint":false},{"pmid":"18680201","id":"PMC_18680201","title":"Localization of Kv2.2 protein in Xenopus laevis embryos and tadpoles.","date":"2008","source":"The Journal of comparative neurology","url":"https://pubmed.ncbi.nlm.nih.gov/18680201","citation_count":9,"is_preprint":false},{"pmid":"12399537","id":"PMC_12399537","title":"The Kv2.2 alpha subunit contributes to delayed rectifier K(+) currents in myocytes from rabbit corpus cavernosum.","date":"2002","source":"Journal of andrology","url":"https://pubmed.ncbi.nlm.nih.gov/12399537","citation_count":9,"is_preprint":false},{"pmid":"15306626","id":"PMC_15306626","title":"Carboxyl tail region of the Kv2.2 subunit mediates novel developmental regulation of channel density.","date":"2004","source":"Journal of neurophysiology","url":"https://pubmed.ncbi.nlm.nih.gov/15306626","citation_count":8,"is_preprint":false},{"pmid":"33803465","id":"PMC_33803465","title":"Regulation of K+ Conductance by a Hydrogen Bond in Kv2.1, Kv2.2, and Kv1.2 Channels.","date":"2021","source":"Membranes","url":"https://pubmed.ncbi.nlm.nih.gov/33803465","citation_count":6,"is_preprint":false},{"pmid":"38075025","id":"PMC_38075025","title":"Glucocorticoids modulate neural activity via a rapid non-genomic effect on Kv2.2 channels in the central nervous system.","date":"2023","source":"Neurobiology of stress","url":"https://pubmed.ncbi.nlm.nih.gov/38075025","citation_count":6,"is_preprint":false},{"pmid":"40028769","id":"PMC_40028769","title":"The Kv2.2 channel mediates the inhibition of prostaglandin E2 on glucose-stimulated insulin secretion in pancreatic β-cells.","date":"2025","source":"eLife","url":"https://pubmed.ncbi.nlm.nih.gov/40028769","citation_count":3,"is_preprint":false},{"pmid":"39577484","id":"PMC_39577484","title":"The KCNB2 gene and its role in neurodevelopmental disorders: Implications for genetics and therapeutic advances.","date":"2024","source":"Clinica chimica acta; international journal of clinical chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/39577484","citation_count":2,"is_preprint":false},{"pmid":"37645613","id":"PMC_37645613","title":"EZH2 and matrix co-regulate phenotype and KCNB2 expression in bladder smooth muscle cells.","date":"2023","source":"American journal of clinical and experimental urology","url":"https://pubmed.ncbi.nlm.nih.gov/37645613","citation_count":1,"is_preprint":false},{"pmid":"40494277","id":"PMC_40494277","title":"Taking the \"lazy\" way identifies KCNB2 as a regulator of SHH-MB maintenance.","date":"2025","source":"Developmental cell","url":"https://pubmed.ncbi.nlm.nih.gov/40494277","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2025.06.04.657913","title":"Kv2/Kv6.4 heteromeric potassium channels are expressed in spinal motor neurons and localized at C-bouton synapses","date":"2025-06-05","source":"bioRxiv","url":"https://doi.org/10.1101/2025.06.04.657913","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":14598,"output_tokens":5292,"usd":0.061587,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":13488,"output_tokens":4998,"usd":0.096195,"stage2_stop_reason":"end_turn"},"total_usd":0.157782,"stage1_batch_id":"msgbatch_01DUPACZi7AAWwuZiUjseQF4","stage2_batch_id":"msgbatch_018yt7chE3f48PEFtDwtj6AE","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1996,\n      \"finding\": \"A novel beta subunit, mKvbeta4, specifically associates with Kv2.2 (CDRK/KCNB2) but not the closely related Kv2.1, enhancing Kv2.2 expression level up to 6-fold at the plasma membrane without changing its elementary conductance or kinetics. The C-terminal end of Kv2.2 is essential for mKvbeta4 sensitivity. The effect is proposed to be chaperone-like, permitting integration of more channels at the plasma membrane.\",\n      \"method\": \"Xenopus oocyte co-expression, chimeric channel analysis between Kv2.1 and Kv2.2, co-localization of transcripts in brain\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-expression functional assay plus chimeric subunit mapping, single lab, two orthogonal methods\",\n      \"pmids\": [\"8824288\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"Angiotensin II, acting through AT1 receptors, inhibits Kv2.2 currents in hypothalamic/brainstem neurons. Co-expression of Kv2.2 and the AT1 receptor in Xenopus oocytes confirmed Ang II-induced inhibition of Kv2.2 current. This inhibition contributes to increased neuronal firing rate relevant to cardiovascular regulation.\",\n      \"method\": \"Patch-clamp electrophysiology of neuronal cocultures, Xenopus oocyte co-expression, RT-PCR, Western blot, pharmacological dissection\",\n      \"journal\": \"Circulation research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — heterologous reconstitution plus native neuronal electrophysiology, single lab, two orthogonal methods\",\n      \"pmids\": [\"10024310\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"The proximal carboxyl terminus (proxC domain) of Kv2.2 mediates a developmental, subunit-specific regulation of channel density in Xenopus spinal neurons. Kv2.2 overexpression increases IKv density in young but not mature neurons; chimeric Kv2 subunits lacking the proxC domain of Kv2.2 rescued current density increase in mature neurons, identifying proxC as responsible for restricting functional expression at mature stages.\",\n      \"method\": \"Chimeric Kv2.1/Kv2.2 subunit expression in Xenopus embryos, heterologous expression in oocytes, in vivo current measurements\",\n      \"journal\": \"Journal of neurophysiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — chimeric subunit domain mapping with in vivo and heterologous functional assays, single lab, two orthogonal methods\",\n      \"pmids\": [\"15306626\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Kv2.2 interacts with syntaxin 1A (a t-SNARE) but, unlike Kv2.1, does not interact with the syntaxin 1A/SNAP-25 complex and is therefore insensitive to the assembly/disassembly state of this SNARE complex. This distinct regulation is attributed to differences in the C-termini of Kv2.1 and Kv2.2. Immunohistochemistry showed Kv2.2 is the dominant Kv channel in pancreatic alpha and delta cells (not beta cells), suggesting SNARE-Kv2.2 interactions regulate glucagon and somatostatin secretion.\",\n      \"method\": \"Two-electrode voltage clamp in Xenopus oocytes, immunohistochemistry, comparative functional analysis of Kv2.1 vs Kv2.2 with syntaxin 1A and SNAP-25 co-expression\",\n      \"journal\": \"Molecular pharmacology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — heterologous reconstitution with functional readout plus immunolocalization, single lab, two orthogonal methods\",\n      \"pmids\": [\"16754785\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Kv2.2 channels are highly expressed at the axon initial segment of MNTB neurons. Hodgkin-Huxley modelling and current-clamp recordings demonstrated that Kv2.2 plays a minor role during single action potentials but hyperpolarizes interspike potentials during repetitive firing, thereby assisting recovery of voltage-gated sodium channels from inactivation and maintaining action potential amplitude at high frequencies.\",\n      \"method\": \"Quantitative RT-PCR, immunofluorescence confocal imaging, Western blot (including Kv2.2 knockout tissue), patch-clamp electrophysiology, Hodgkin-Huxley modelling\",\n      \"journal\": \"The Journal of physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (KO confirmation, localization, electrophysiology, modelling), replicated across approaches in single rigorous study\",\n      \"pmids\": [\"18511484\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"In Xenopus laevis neurons, Kv2.2 protein localizes to long axonal-like processes and colocalizes with alpha-tubulin intracellularly, contrasting with Kv2.1 which is somatodendritic. This differential subcellular localization supports distinct functional roles for the two paralogs during development.\",\n      \"method\": \"Antibody development and immunodetection in Xenopus embryos and cultured neurons, Western blot specificity confirmation (Kv2.2 vs Kv2.1), confocal imaging\",\n      \"journal\": \"The Journal of comparative neurology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — immunolocalization with specificity controls and comparison to Kv2.1, single lab\",\n      \"pmids\": [\"18680201\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Kv2.2 is abundantly expressed in a large subpopulation (~60%) of GABAergic neurons in the magnocellular preoptic nucleus (MCPO) and horizontal limb of the diagonal band of Broca (HDB) of the basal forebrain, identified using specific immunolabeling and GFP-knockin mice expressing GFP in GABAergic neurons.\",\n      \"method\": \"Immunolabeling, GFP-knockin reporter mice (GAD67-GFP), confocal microscopy\",\n      \"journal\": \"The Journal of comparative neurology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — cell-type-specific localization with genetic reporter mouse and immunolabeling, single lab\",\n      \"pmids\": [\"20853508\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Kv2.2 specifically regulates somatostatin release from pancreatic delta-cells. shRNA-mediated knockdown of Kv2.2 in mouse islets selectively enhanced somatostatin secretion without affecting insulin secretion. Pharmacological inhibition with GxTX-1E (which blocks both Kv2.1 and Kv2.2) also enhanced somatostatin release, including in Kv2.1 knockout mice, confirming a Kv2.2-dependent mechanism in delta-cells.\",\n      \"method\": \"Adenovirus-delivered shRNA knockdown, selective peptide (GxTX-1E) and small molecule (RY796) inhibitors, Kv2.1 knockout mice, isolated islet secretion assays, perfused pancreata\",\n      \"journal\": \"The Journal of pharmacology and experimental therapeutics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic knockdown plus pharmacology plus KO mouse model, multiple orthogonal approaches in a single rigorous study\",\n      \"pmids\": [\"23161216\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Kv2.2 regulates neuronal excitability in VNTB neurons of the medial olivocochlear system by maintaining short action potentials and enabling high-frequency firing. Viral dominant-negative Kv2.2 gene transfer suppressed outward K+ currents, increased AP half-width, and reduced repetitive firing. Kv2.2 knockout mice showed the same AP duration increase and were more susceptible to noise-induced hearing loss.\",\n      \"method\": \"Viral gene transfer of dominant-negative Kv2.2, Kv2.2 knockout mice, patch-clamp electrophysiology, in vivo auditory brainstem response recordings\",\n      \"journal\": \"The Journal of neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — dominant-negative plus germline KO with electrophysiology and in vivo functional readout, multiple orthogonal methods\",\n      \"pmids\": [\"23699522\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"miR-1 targets KCNB2 (and KCNE1) directly, as confirmed by luciferase activity assay. Upregulation of miR-1 during atrial tachypacing downregulates KCNB2, contributing to shortening of atrial effective refractory period and increased IKs.\",\n      \"method\": \"Luciferase reporter assay (direct target confirmation), lentiviral miR-1 overexpression, siRNA knockdown, patch-clamp, in vivo AERP measurement\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct luciferase validation of miR-1 targeting KCNB2 plus functional electrophysiological readout, single lab\",\n      \"pmids\": [\"24386485\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Pyruvate-isocitrate cycling (via cytosolic NADP-dependent isocitrate dehydrogenase, ICDc) regulates Kv2.2 expression in islet beta-cells. Immunoprecipitation demonstrated physical interaction between Kv2.1 and Kv2.2. Co-overexpression of Kv2.1 and Kv2.2 reduced outward K+ current compared with Kv2.1 alone, supporting Kv2.2 as a negative modulator of Kv channel activity. Kv2.2 knockdown rescued the GSIS defect caused by ICDc knockdown.\",\n      \"method\": \"siRNA knockdown, adenoviral re-expression, co-immunoprecipitation, patch-clamp electrophysiology, selective inhibitor stromatoxin1\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal co-IP for Kv2.1/Kv2.2 interaction plus functional epistasis rescue, single lab, two orthogonal methods\",\n      \"pmids\": [\"23788641\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Kv2.2-expressing GABAergic neurons in the basal forebrain are preferentially active during waking (c-Fos labeling) and regulate the sleep-wake cycle. Kv2.2 knockout mice exhibited longer consolidated wake bouts and reduced delta-frequency EEG activity during NREM sleep. Basal forebrain GABAergic neurons showed augmented c-Fos expression in Kv2.2 knockout mice.\",\n      \"method\": \"Kv2.2 knockout mice, EEG/EMG sleep recordings, c-Fos immunostaining, sleep deprivation protocol\",\n      \"journal\": \"Sleep\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — germline KO with defined physiological phenotype and neuronal activity marker, single lab\",\n      \"pmids\": [\"24293758\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Protein kinase C (PKC) phosphorylates Kv2.2 at residues S481 and S488, inhibiting Kv2.2 currents and altering steady-state activation. Point mutations at S481 and S488 abolished PKC-dependent modulation. In cortical layer II pyramidal neurons, PKC activation similarly inhibited native Kv2.2 channels and reduced action potential firing frequency.\",\n      \"method\": \"PKC activation in HEK293 cells expressing Kv2.2, point mutagenesis (S481A, S488A), phospho-specific antibodies, patch-clamp in native cortical neurons\",\n      \"journal\": \"Neuroscience bulletin\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — site-directed mutagenesis identifying phosphorylation sites plus functional validation in native neurons, two orthogonal methods, single lab\",\n      \"pmids\": [\"34542799\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"An inter-subunit hydrogen bond formed by W366 and Y376 (Kv2.1 numbering; conserved in Kv2.2) is essential for K+ conductance. Mutations disrupting this H-bond caused complete loss of K+ conductance in Kv2.1, Kv2.2, and Kv1.2 channels, differing from the Shaker inactivation mechanism.\",\n      \"method\": \"Point mutagenesis, patch-clamp recording in cells expressing Kv2.2 and related channels\",\n      \"journal\": \"Membranes\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — mutagenesis with functional electrophysiology, single lab, single method\",\n      \"pmids\": [\"33803465\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Cortisol (glucocorticoid) rapidly increases Kv2.2 currents by increasing single-channel open probability through activation of a membrane-associated glucocorticoid receptor, independent of genomic signaling. This effect is mediated through the ERK1/2 kinase pathway (blocked by U0126). A membrane-impermeable glucocorticoid receptor agonist (BSA-dexamethasone) mimicked the effect. In cortical pyramidal neurons and calyx of Held synapses, cortisol suppressed AP firing frequency and increased activity-dependent synaptic depression via Kv2.2 activation.\",\n      \"method\": \"Single-channel patch-clamp in HEK293 cells expressing Kv2.2, pharmacological inhibition (U0126, EP receptor antagonists), membrane-impermeable agonist, patch-clamp in acute brain slices\",\n      \"journal\": \"Neurobiology of stress\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — single-channel recordings plus pathway inhibition plus native neuron recordings, single lab, multiple orthogonal methods\",\n      \"pmids\": [\"38075025\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"EZH2-mediated H3K27me3 histone trimethylation at the KCNB2 promoter (CpG island and upstream region) represses KCNB2 expression in bladder smooth muscle cells during obstruction. EZH2 inhibition (UNC1999) restored KCNB2 expression and partially restored smooth muscle cell phenotype. Matrix conditions regulate EZH2 and H3K27me3 levels affecting KCNB2 expression.\",\n      \"method\": \"ChIP/PCR for H3K27me3 at KCNB2 promoter in obstruction tissue, EZH2 inhibitor treatment, siRNA knockdown of KCNB2, Western blotting, immunostaining\",\n      \"journal\": \"American journal of clinical and experimental urology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP at the KCNB2 promoter plus pharmacological and siRNA functional validation, single lab\",\n      \"pmids\": [\"37645613\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"PGE2 inhibits Kv2.2 channels via PKA-dependent phosphorylation at residue S448, acting through EP2/4 receptors. Point mutation of S448 blocked the PKA-dependent PGE2 inhibition. In INS-1 beta-cells, PGE2 inhibited voltage-gated K+ currents and electrical activity through EP2/4 receptors and Kv2.2. Kcnb2 knockout mice showed abrogated PGE2-induced glucose intolerance, and Kv2.2 knockdown alleviated PGE2 inhibition of GSIS.\",\n      \"method\": \"HEK293T overexpression, point mutagenesis (S448A), PKA pathway manipulation, EP receptor antagonists/agonists, INS-1 beta-cell electrophysiology, Kcnb2 knockout mice, glucose tolerance testing, islet GSIS assays\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — site-directed mutagenesis identifying phosphorylation site, plus KO mouse phenotyping, plus native cell electrophysiology, multiple orthogonal methods in single study\",\n      \"pmids\": [\"40028769\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Kv2.2 co-assembles with the electrically-silent subunit Kv6.4 and co-clusters with Kv2.1 at endoplasmic reticulum-plasma membrane (ER-PM) junctions beneath C-bouton synapses in spinal motor neurons. In Kv2.2 knockout mice, Kv6.4 clustering at ER-PM junctions is moderately reduced, indicating that Kv2.2 contributes to the localization and expression of Kv6.4 through co-assembly. AMIGO-1 auxiliary subunit clustering is also moderately reduced in Kv2.2 KO mice.\",\n      \"method\": \"Immunofluorescence co-localization, Kv2.1 S590A mutant mice, Kv2.1 and Kv2.2 knockout mice, confocal and super-resolution microscopy\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-localization with multiple KO/mutant mouse models, single lab, preprint not yet peer-reviewed\",\n      \"pmids\": [\"bio_10.1101_2025.06.04.657913\"],\n      \"is_preprint\": true\n    }\n  ],\n  \"current_model\": \"KCNB2 (Kv2.2) encodes a voltage-gated delayed rectifier K+ channel that localizes preferentially to axon initial segments and ER-PM junctions, forms heteromeric complexes with Kv2.1 and electrically-silent KvS subunits (Kv6.4), and is regulated by multiple post-translational modifications including PKC-mediated phosphorylation at S481/S488 (inhibitory), PKA-mediated phosphorylation at S448 downstream of PGE2/EP2-4 receptor signaling (inhibitory), and ERK1/2-mediated activation downstream of membrane glucocorticoid receptor; its activity is also modulated by the beta subunit mKvbeta4 (which enhances surface expression via the Kv2.2 C-terminus) and by t-SNAREs (syntaxin 1A alone, but not the syntaxin/SNAP-25 complex); in neurons it maintains high-frequency action potential firing by hyperpolarizing interspike potentials and enabling Nav channel recovery, and in pancreatic delta-cells it specifically controls somatostatin secretion while in beta-cells it modulates GSIS through its interaction with Kv2.1 and the EP2/4-Kv2.2-PKA pathway.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"KCNB2 encodes Kv2.2, a voltage-gated delayed rectifier K+ channel that tunes neuronal excitability and endocrine secretion by shaping repolarization during sustained electrical activity [#4, #8]. In auditory brainstem neurons it concentrates at the axon initial segment, where it contributes little to single spikes but hyperpolarizes interspike potentials during repetitive firing, promoting recovery of voltage-gated Na+ channels from inactivation and thereby sustaining high-frequency action potential firing [#4, #8]. Its functional output is set by subunit context: Kv2.2 physically interacts with Kv2.1 and acts as a negative modulator of the resulting heteromeric current [#10], co-assembles with the electrically-silent KvS subunit Kv6.4 at ER-PM junctions and supports Kv6.4 clustering [#17], and binds the t-SNARE syntaxin 1A in a manner distinct from Kv2.1 [#3], while the accessory subunit mKvbeta4 selectively boosts Kv2.2 surface expression through its C-terminus [#0]. Channel activity is further controlled by post-translational modification, being inhibited by PKC phosphorylation at S481/S488 [#12] and by PKA phosphorylation at S448 downstream of PGE2/EP2-4 signaling [#16], yet activated by a non-genomic membrane glucocorticoid receptor pathway acting through ERK1/2 [#14]. Beyond neurons, Kv2.2 governs hormone secretion in pancreatic islets, selectively restraining somatostatin release from delta-cells [#7] and modulating glucose-stimulated insulin secretion via its interaction with Kv2.1 and the EP2/4-PKA axis [#10, #16]. KCNB2 expression is itself regulated transcriptionally and post-transcriptionally, being a direct target of miR-1 [#9] and repressed by EZH2-mediated H3K27me3 at its promoter [#15].\",\n  \"teleology\": [\n    {\n      \"year\": 1996,\n      \"claim\": \"Established that Kv2.2 surface expression is governed by a dedicated accessory subunit, distinguishing its regulation from the paralog Kv2.1.\",\n      \"evidence\": \"Xenopus oocyte co-expression with mKvbeta4 and Kv2.1/Kv2.2 chimeric mapping\",\n      \"pmids\": [\"8824288\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Chaperone-like mechanism inferred but not biochemically resolved\", \"Physiological relevance in native neurons not tested\"]\n    },\n    {\n      \"year\": 1999,\n      \"claim\": \"Showed Kv2.2 is a downstream effector of GPCR signaling, linking AT1 receptor activation to suppression of K+ current and increased neuronal firing.\",\n      \"evidence\": \"Patch-clamp of neuronal cocultures plus AT1/Kv2.2 co-expression in oocytes\",\n      \"pmids\": [\"10024310\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Molecular mechanism of inhibition not defined\", \"No phosphorylation site identified\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Mapped a proximal C-terminal domain controlling developmental, stage-specific restriction of Kv2.2 functional density.\",\n      \"evidence\": \"Chimeric Kv2.1/Kv2.2 subunit expression in Xenopus embryos and oocytes\",\n      \"pmids\": [\"15306626\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Binding partners mediating proxC restriction unknown\", \"Restricted to amphibian development\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Defined a paralog-specific SNARE interaction, showing Kv2.2 binds syntaxin 1A but is insensitive to the syntaxin/SNAP-25 complex, implying a distinct role in islet hormone secretion.\",\n      \"evidence\": \"Two-electrode voltage clamp with syntaxin 1A/SNAP-25 co-expression plus islet immunohistochemistry\",\n      \"pmids\": [\"16754785\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct effect on glucagon/somatostatin secretion not measured here\", \"C-terminal determinant of selectivity not mutationally mapped\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Resolved the core neuronal function of Kv2.2: AIS-localized channels hyperpolarize interspike potentials to enable Nav recovery and high-frequency firing.\",\n      \"evidence\": \"RT-PCR, immunofluorescence, KO tissue Western blot, patch-clamp, and Hodgkin-Huxley modelling in MNTB neurons\",\n      \"pmids\": [\"18511484\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not address heteromerization with Kv2.1 in this context\", \"AIS targeting mechanism not defined\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Demonstrated axonal localization of Kv2.2 distinct from somatodendritic Kv2.1, supporting divergent paralog roles.\",\n      \"evidence\": \"Specificity-controlled immunodetection and confocal imaging in Xenopus neurons\",\n      \"pmids\": [\"18680201\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Trafficking determinants not identified\", \"Tubulin colocalization mechanism unresolved\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Identified a defined Kv2.2-expressing cell population, GABAergic basal forebrain neurons, anchoring later circuit-level studies.\",\n      \"evidence\": \"Immunolabeling combined with GAD67-GFP knockin reporter mice\",\n      \"pmids\": [\"20853508\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional consequence in these neurons not tested here\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Established a non-redundant endocrine role: Kv2.2 selectively controls somatostatin secretion from pancreatic delta-cells independent of Kv2.1.\",\n      \"evidence\": \"shRNA knockdown, GxTX-1E/RY796 pharmacology, and Kv2.1 KO islet/pancreas secretion assays\",\n      \"pmids\": [\"23161216\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Coupling between channel activity and somatostatin exocytosis not mechanistically dissected\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Connected Kv2.2 to auditory function, showing it maintains short APs and high-frequency firing and protects against noise-induced hearing loss.\",\n      \"evidence\": \"Dominant-negative viral transfer, Kv2.2 KO mice, patch-clamp, and auditory brainstem responses\",\n      \"pmids\": [\"23699522\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Subunit composition of native VNTB currents not defined\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Showed Kv2.2 is a direct miR-1 target, linking microRNA regulation of KCNB2 to atrial electrical remodeling.\",\n      \"evidence\": \"Luciferase reporter assay plus miR-1 overexpression/knockdown and electrophysiology\",\n      \"pmids\": [\"24386485\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Cardiac Kv2.2 channel function not directly recorded\", \"Relative contribution versus KCNE1 not separated\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Demonstrated Kv2.2 physically interacts with Kv2.1 and negatively modulates the heteromeric current, integrating it into beta-cell metabolic control of insulin secretion.\",\n      \"evidence\": \"Co-immunoprecipitation, co-overexpression patch-clamp, and ICDc knockdown/rescue epistasis in islet beta-cells\",\n      \"pmids\": [\"23788641\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Stoichiometry of Kv2.1/Kv2.2 heteromers undefined\", \"Structural basis of negative modulation unknown\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Linked Kv2.2 to behavioral physiology by showing its loss alters sleep-wake architecture via basal forebrain GABAergic neurons.\",\n      \"evidence\": \"Kv2.2 KO mice with EEG/EMG recordings and c-Fos activity mapping\",\n      \"pmids\": [\"24293758\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Cell-autonomous channel contribution not isolated from network effects\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Identified PKC phosphorylation sites S481/S488 as an inhibitory switch on Kv2.2 controlling cortical neuron firing.\",\n      \"evidence\": \"PKC activation in HEK293, S481A/S488A mutagenesis, phospho-antibodies, and native cortical neuron patch-clamp\",\n      \"pmids\": [\"34542799\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Upstream receptor coupling to PKC not specified\", \"Interaction with other phospho-regulation not tested\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Defined a conserved inter-subunit W366-Y376 hydrogen bond required for K+ conductance, a structural determinant distinct from Shaker inactivation.\",\n      \"evidence\": \"Point mutagenesis and patch-clamp across Kv2.1, Kv2.2, and Kv1.2\",\n      \"pmids\": [\"33803465\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structural model of the bonded state\", \"Single method, functional inference only\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Revealed a rapid non-genomic glucocorticoid pathway that activates Kv2.2 via a membrane GR and ERK1/2, modulating neuronal firing and synaptic depression.\",\n      \"evidence\": \"Single-channel patch-clamp in HEK293, U0126 inhibition, membrane-impermeable agonist, and brain slice recordings\",\n      \"pmids\": [\"38075025\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct ERK1/2 phosphorylation site on Kv2.2 not mapped\", \"Membrane GR identity not molecularly defined\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Established epigenetic repression of KCNB2 by EZH2-mediated H3K27me3, linking matrix conditions to channel downregulation in bladder smooth muscle.\",\n      \"evidence\": \"ChIP for H3K27me3 at the KCNB2 promoter, EZH2 inhibition, and KCNB2 siRNA\",\n      \"pmids\": [\"37645613\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Smooth muscle Kv2.2 channel function not electrophysiologically characterized\", \"Direct EZH2-KCNB2 causality versus broader program not fully separated\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Identified PKA phosphorylation at S448 as the molecular basis for PGE2/EP2-4 inhibition of Kv2.2, with in vivo consequences for glucose homeostasis.\",\n      \"evidence\": \"S448A mutagenesis, EP receptor pharmacology, INS-1 electrophysiology, and Kcnb2 KO glucose tolerance/GSIS\",\n      \"pmids\": [\"40028769\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Cell-type specificity of the EP2/4-PKA-Kv2.2 axis beyond beta-cells not resolved\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Showed Kv2.2 co-assembles with Kv6.4 and clusters with Kv2.1 at ER-PM junctions, supporting localization of silent subunits and auxiliary AMIGO-1.\",\n      \"evidence\": \"Immunofluorescence colocalization with Kv2.1 S590A and Kv2.1/Kv2.2 KO mice plus super-resolution microscopy (preprint)\",\n      \"pmids\": [\"bio_10.1101_2025.06.04.657913\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional output of Kv2.2/Kv6.4 heteromers not recorded\", \"Preprint, not yet peer-reviewed\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How the multiple regulatory inputs (PKC, PKA, ERK1/2, subunit composition) are integrated to set Kv2.2 output in a given cell type, and the structural basis of its negative modulation of Kv2.1, remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No integrated model of competing phospho-regulation\", \"Heteromer structure and stoichiometry undefined\", \"Native channel composition across neuronal and endocrine cell types incompletely mapped\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0005215\", \"supporting_discovery_ids\": [4, 8, 13]},\n      {\"term_id\": \"GO:0005216\", \"supporting_discovery_ids\": [4, 8]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [0, 4, 17]},\n      {\"term_id\": \"GO:0005783\", \"supporting_discovery_ids\": [17]},\n      {\"term_id\": \"GO:0005856\", \"supporting_discovery_ids\": [5]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-112316\", \"supporting_discovery_ids\": [4, 8]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [1, 14, 16]}\n    ],\n    \"complexes\": [\"Kv2.1/Kv2.2 heteromeric channel\", \"Kv2.2/Kv6.4 heteromeric channel\", \"ER-PM junction Kv2 cluster\"],\n    \"partners\": [\"KCNB1\", \"KCNG4\", \"STX1A\", \"KCNAB4\", \"AMIGO1\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":6,"faith_pct":100.0}}