Affinage

KCNG4

Voltage-gated potassium channel regulatory subunit KCNG4 · UniProt Q8TDN1

Length
519 aa
Mass
59.0 kDa
Annotated
2026-06-10
31 papers in source corpus 16 papers cited in narrative 16 extracted findings
Cross-family judge vs UniProt: Affinage preferred faithfulness: 8/8 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

KCNG4 encodes Kv6.4, an electrically silent voltage-gated K+ channel subunit that does not form functional homotetramers but assembles into functional heterotetramers with the Kv2.1 pore-forming subunit, where it tunes the voltage dependence and kinetics of channel gating (PMID:19074135, PMID:32697988). Heteromerization is mediated by complementary T1 tetramerization domains, requiring conserved CDD-motif aspartates in the Kv6.4 A/B linker and Kv2.1 residue His105; disrupting either interface abolishes co-assembly and Kv6.4-imposed gating shifts (PMID:19717558, PMID:19074135). Atypical substitutions in the Kv6.4 S6 activation gate restrict functional assembly to a predominant 3:1 Kv2.1:Kv6.4 stoichiometry (PMID:30322883). Within these heteromers Kv6.4 shifts voltage-dependent activation and inactivation, imposes closed-state inactivation that can be relieved pharmacologically by 4-AP through its S6c segment, and the complex can further recruit KCNE5 into a triple complex that further modifies gating kinetics (PMID:26242757, PMID:26505474). Kv6.4-containing channels are distinguished from Kv2-only channels pharmacologically by resistance to the pore blocker RY785 with retained sensitivity to the voltage-sensor modulator GxTX (PMID:40423692). In native tissue Kv6.4 co-clusters with Kv2.1 and Kv2.2 at ER-PM junctions beneath C-bouton synapses in spinal motoneurons in a manner dependent on Kv2.1 and its VAP-binding capacity, and in cortical parvalbumin interneurons it shapes action potential waveform, high-frequency firing, and GABAergic synaptic output by reducing Kv2-mediated delayed-rectifier current (PMID:40919874, PMID:41632839). Physiologically, Kv6.4 confers fast biophysical properties on motor neurons downstream of Dlk1 and is required for normal late-stage spermatogenesis, as its knockout causes male sterility (PMID:27677211, PMID:24626931). Human Kv6.4 variants link the channel to disease: a non-trafficking dominant-negative variant elevates uterine nociceptor action-potential threshold and influences labor pain, and an S4-S5 linker missense mutation associated with migraine impairs Kv2.1/Kv6.4 function (PMID:32697988, PMID:39159549).

Mechanistic history

Synthesis pass · year-by-year structured walk · 13 steps
  1. 2008 High

    Established the molecular interface for Kv6.4 heteromerization, showing that a specific T1-domain residue in the Kv2.1 partner is required for assembly and for Kv6.4's functional gating effect.

    Evidence Yeast two-hybrid, FRET, co-IP and electrophysiology with Kv2.1 H105 mutants

    PMID:19074135

    Open questions at the time
    • Did not define the reciprocal Kv6.4 residues
    • Stoichiometry of the heteromer not resolved
  2. 2009 High

    Identified the Kv6.4 side of the assembly interface, showing conserved CDD-motif aspartates in the T1 A/B linker are required for heterotetramerization with Kv2.1.

    Evidence Site-directed mutagenesis, co-IP and FRET in HEK cells

    PMID:19717558

    Open questions at the time
    • Did not establish assembly stoichiometry
    • Structural basis of the linker contact not resolved
  3. 2011 Medium

    Mapped intramembrane S1-S4-S5 residue couplings critical for maturation and gating of functional Kv2.1/Kv6.4 chimeric channels.

    Evidence Chimeric channels and double mutant cycle analysis with electrophysiology

    PMID:21455829

    Open questions at the time
    • Used chimeras rather than native heteromers
    • Single-lab mechanistic study
  4. 2014 High

    Placed Kv6.4 in a developmental gene regulatory program, showing Dlk1 activates Kcng4 to confer fast biophysical properties on motor neurons.

    Evidence Transgenic mouse/chick gain- and loss-of-function, electrophysiology, transcriptomics

    PMID:24626931

    Open questions at the time
    • Mechanism by which Dlk1 induces Kcng4 transcription not defined
    • Direct contribution of Kv6.4 currents versus other Dlk1 targets not isolated
  5. 2015 High

    Defined the pharmacological and accessory-subunit modulation of the heteromer: KCNE5 forms a triple complex altering kinetics, and 4-AP potentiates currents by relieving Kv6.4-imposed closed-state inactivation via S6c.

    Evidence FRET and electrophysiology in HEK293, chimeric Kv6.4/Kv9.3 substitutions in oocytes

    PMID:26242757 PMID:26505474

    Open questions at the time
    • Physiological relevance of the KCNE5 triple complex in native tissue not shown
    • 4-AP mechanism mapped to S6c but exact binding determinants unresolved
  6. 2017 High

    Revealed an unexpected reproductive requirement, showing Kcng4 knockout causes male sterility through disturbed spermiogenesis.

    Evidence Targeted knockout mouse, semen analysis, testicular histology

    PMID:27677211

    Open questions at the time
    • Channel partner and current responsible in germ cells not identified
    • Cellular mechanism linking K+ conductance to sperm morphogenesis unknown
  7. 2018 High

    Explained why heteromers adopt a fixed stoichiometry, showing atypical Kv6.4 S6 gate substitutions restrict functional assembly to 3:1 Kv2.1:Kv6.4.

    Evidence Concatemer/tandem-dimer constructs, mutagenesis, electrophysiology

    PMID:30322883

    Open questions at the time
    • Whether 2:2 species assemble but are non-functional not fully resolved
    • Structural conformation of the mixed gate not determined
  8. 2020 High

    Connected Kv6.4 to human physiology and disease, showing it traffics to the membrane to modulate Kv2.1 inactivation and that a non-trafficking dominant-negative variant raises action-potential threshold in uterine nociceptors.

    Evidence Neuronal expression, trafficking assays, patch clamp, in vivo retrograde labeling, human genetic association

    PMID:32697988

    Open questions at the time
    • Causal link from nociceptor threshold to labor pain phenotype indirect
    • Trafficking determinants of the variant not mapped
  9. 2024 Medium

    Provided a molecular mechanism for migraine association, showing the S4-S5 linker L360P mutation impairs or abolishes Kv2.1/Kv6.4 currents.

    Evidence Electrophysiology with monomeric and fixed-stoichiometry tandem dimer constructs co-expressed with Kv2.1

    PMID:39159549 PMID:39201645

    Open questions at the time
    • Dominant-negative mechanism inferred from heterologous expression only
    • Direct demonstration in trigeminal neurons lacking
  10. 2024 Medium

    Demonstrated that distinct functional states of Kv6.4-containing channels control hollow organ morphogenesis, using zebrafish loss- and gain-of-function ear alleles.

    Evidence Zebrafish mutant analysis, electrophysiology, structural modelling

    PMID:38492873

    Open questions at the time
    • Channel partner in developing ear not defined
    • Mechanism linking conductance state to kinocilia/otolith defects unknown
  11. 2025 High

    Localized native Kv6.4 to ER-PM junctions beneath C-bouton synapses in spinal motoneurons and showed clustering depends on Kv2.1 and its VAP-binding ability.

    Evidence Immunofluorescence and confocal microscopy in Kv2.1 KO, Kv2.2 KO and Kv2.1-S590A knockin mice

    PMID:40919874

    Open questions at the time
    • Functional consequence of ER-PM clustering for motoneuron firing not directly tested
    • Role of the C-bouton localization in motor output undefined
  12. 2025 High

    Defined Kv6.4's role in cortical inhibitory circuits and its native pharmacological signature, showing loss alters PV-neuron action potential waveform, high-frequency firing and GABA release, and that Kv6.4-containing channels are RY785-resistant/GxTX-sensitive in native neurons.

    Evidence Knockout mouse patch-clamp (intrinsic and synaptic) plus pharmacological dissection with RY785/GxTX in mouse and human DRG and SCG neurons

    PMID:40423692 PMID:41632839

    Open questions at the time
    • Network-level behavioral consequences in mammals not established
    • Relative contribution of Kv2.1 versus Kv2.2 partners in PV neurons not resolved
  13. 2025 Medium

    Linked Kv6.4/Kv2.1 loss to disrupted inhibitory neurotransmission and seizure susceptibility in zebrafish.

    Evidence Zebrafish loss-of-function mutants, behavioral assays, qRT-PCR, local field potential recordings (preprint)

    PMID:40501962

    Open questions at the time
    • Preprint, not peer-reviewed
    • Mechanism connecting channel loss to altered GABAergic transcripts not established

Open questions

Synthesis pass · forward-looking unresolved questions
  • How Kv6.4 K+ conductance is mechanistically coupled to its diverse organ-level roles—spermiogenesis, ear morphogenesis, and labor/migraine nociception—remains unresolved.
  • No structural model of the assembled Kv2.1/Kv6.4 heteromer
  • Tissue-specific partners outside neurons not identified
  • Causal chain from channel biophysics to morphogenetic phenotypes unknown

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0005215 transporter activity 3 GO:0098772 molecular function regulator activity 3
Localization
GO:0005886 plasma membrane 2 GO:0005783 endoplasmic reticulum 1
Pathway
R-HSA-112316 Neuronal System 2 R-HSA-1266738 Developmental Biology 2
Partners
Complex memberships
Kv2.1/Kv6.4 heterotetramerKv2.1/Kv6.4/KCNE5 triple complex

Evidence

Reading pass · 16 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2009 Conserved negatively charged aspartates (CDD motif) in the A/B linker of the T1 tetramerization domain are required for efficient assembly of both homotetrameric Kv2.1 and heterotetrameric Kv2.1/Kv6.4 channels; arginine substitution in Kv6.4 at this position prevented its heterotetrameric interaction with Kv2.1, as shown by FRET and co-immunoprecipitation. Site-directed mutagenesis, co-immunoprecipitation, FRET (confocal microscopy), immunocytochemistry in HEK cells The Journal of biological chemistry High 19717558
2008 Histidine 105 in the T1 domain of Kv2.1 is required for heteromerization with Kv6.4; H105V or H105R mutations disrupted T1–T1 interaction with Kv6.4 (and Kv6.3), prevented co-immunoprecipitation of Kv2.1 with Kv6.4, reduced FRET signal, and abolished Kv6.4-mediated shift in voltage dependence of activation. Yeast two-hybrid, FRET, co-immunoprecipitation, electrophysiology (two-electrode voltage clamp), dominant-negative co-expression The Journal of biological chemistry High 19074135
2015 KCNE5 forms a triple complex with Kv2.1 and Kv6.4, modifying Kv2.1/Kv6.4 biophysical properties (accelerated activation, slowed deactivation, steepened inactivation slope, accelerated recovery from closed-state inactivation) without altering current density, as demonstrated by FRET and electrophysiology in HEK293 cells. Electrophysiology (patch clamp in HEK293 cells), FRET, immunocytochemistry Scientific reports High 26242757
2015 4-AP potentiates Kv2.1/Kv6.4 currents by suppressing Kv6.4-mediated closed-state inactivation, recovering channels inactivated at resting potential; the lower half of the S6 domain (S6c) of Kv6.4 plays a crucial role in this 4-AP-induced potentiation, as shown by chimeric substitutions between Kv6.4 and Kv9.3. Electrophysiology (two-electrode voltage clamp in Xenopus oocytes), chimeric subunit substitutions PloS one High 26505474
2018 The S6 activation gate of Kv6.4 contains atypical substitutions that restrict the functional stoichiometry of Kv2.1:Kv6.4 heteromers to 3:1 (Kv2.1:Kv6.4); two amino acid substitutions in the S6 gate of Kv6.4 limit formation and function of 2:2 heteromers, and substituting the self-compatible Kv2.1 T1 domain into Kv6.4 does not alter stoichiometry. Electrophysiology, concatemer/tandem dimer constructs, mutagenesis, comparative sequence analysis with cnidarian orthologs The Journal of general physiology High 30322883
2011 Residues T203 in S1 and S347 in S5 of Kv2.1 are energetically coupled and interact with S4 residue R300; double mutant cycle analysis showed these specific S1–S4–S5 interactions are critical for Kv2.1 channel maturation and gating, and are important determinants for the functional Kv2.1/Kv6.4 chimeric channel. Chimeric Kv2.1/Kv6.4 channels, site-directed mutagenesis, double mutant cycle analysis, electrophysiology European biophysics journal Medium 21455829
2020 KV6.4 traffics to the plasma membrane to modulate the voltage dependence of KV2.1 inactivation; the rare variant KV6.4-Met419 (rs140124801) fails to traffic to the plasma membrane, exerts a dominant-negative effect, and cannot modulate KV2.1 inactivation, resulting in a more depolarized voltage dependence of inactivation and a higher action potential threshold in neurons overexpressing the mutant. Functional expression in neurons, electrophysiology (patch clamp), plasma membrane trafficking assay, in vivo retrograde labeling of mouse uterine sensory neurons, human genetic association Cell reports High 32697988
2017 Targeted deletion of Kv6.4 (Kcng4-/-) in mice causes male sterility due to disturbed spermiogenesis, manifested by severe reduction in sperm count, absence of motile spermatozoa, and abnormal sperm morphology (smaller head, shorter tail), indicating Kv6.4 is required for normal late-stage spermatogenesis. Knockout mouse model (targeted gene deletion), semen quality analysis, histology of testicular tissue Reproduction, fertility, and development High 27677211
2014 Dlk1 activates expression of Kv6.4 (Kcng4) in motor neurons to modulate delayed-rectifier K+ currents, promoting a fast biophysical signature; Dlk1 inactivation shifts motor neurons toward slow biophysical properties and abolishes peak force outputs. Transgenic mouse and chick models, electrophysiology, transcriptome analysis, gain- and loss-of-function experiments Science High 24626931
2024 The migraine-linked Kv6.4-L360P missense mutation in the S4-S5 linker significantly impairs function of Kv2.1/Kv6.4 channels; when expressed in fixed 2:2 stoichiometry (monomeric and tandem dimer configurations), L360P alters channel biophysical properties, providing a molecular mechanism for channel dysfunction in migraine. Electrophysiology with monomeric and tandem dimer (fixed stoichiometry) channel constructs in expression system Biochemical and biophysical research communications Medium 39159549
2024 Kv6.4-L360P (migraine-linked variant) almost completely abolishes Kv2 currents when co-expressed with Kv2.1, proposed to act through a dominant-negative-like mechanism affecting the trigeminal system. Electrophysiology (heterologous expression with Kv2.1), molecular characterization of variant International journal of molecular sciences Medium 39201645
2024 Two kcng4b mutations in zebrafish (kcng4b-C1 causing mild loss-of-function with C-terminal truncation, and kcng4b-C2 causing gain-of-function by forming an ectopic 7th transmembrane domain) produce distinct ear developmental defects (failure of kinocilia extension and ectopic otoliths for C1; absent otoliths and reduced kinocilia for C2), demonstrating that different functional states of the Kv6.4-containing channel regulate hollow organ development. Zebrafish mutant analysis, electrophysiology, developmental biology, in silico structural modelling Developmental biology Medium 38492873
2025 Kv6.4 is specifically expressed in spinal motoneurons (not other spinal cord neuron classes) and co-clusters with Kv2.1 and Kv2.2 at endoplasmic reticulum-plasma membrane (ER-PM) junctions beneath C-bouton synapses; Kv6.4 clustering depends on Kv2.1 (severely reduced in Kv2.1 KO) and moderately on Kv2.2 (moderately reduced in Kv2.2 KO), and requires Kv2.1's ability to bind ER VAP proteins (absent in Kv2.1-S590A mutant). Immunofluorescence, transgenic/knockout mouse models (Kv2.1 KO, Kv2.2 KO, Kv2.1-S590A knockin), confocal microscopy, subcellular fractionation/localization The European journal of neuroscience High 40919874
2025 In cortical parvalbumin (PV) neurons, Kv6.4 loss (Kcng4 KO) reduces action potential height and width, hyperpolarizes firing threshold and interspike potential, accelerates AP upstroke during repetitive firing, alters GABA release, and changes paired-pulse depression at PV→pyramidal synapses; effects are amplified at high-frequency firing, consistent with Kv6.4 reducing Kv2-mediated delayed rectifier current. Conditional/constitutive knockout mice, patch-clamp electrophysiology (intrinsic and synaptic), in vivo imaging of Kcng4 expression Proceedings of the National Academy of Sciences of the United States of America High 41632839
2025 Dorsal root ganglion (DRG) neurons in mouse and human show predominantly RY785-resistant but GxTX-sensitive conductances, consistent with Kv2/KvS (including Kv6.4-containing) heteromeric channels, whereas superior cervical ganglion neurons show predominantly Kv2-only (RY785-sensitive) conductances; Kv6.4-containing channels are resistant to pore-blocker RY785 but sensitive to voltage-sensor modulator GxTX. Pharmacological dissection with two Kv2 inhibitors (RY785, GxTX), patch-clamp electrophysiology in native neurons (mouse SCG, mouse and human DRG) eLife High 40423692
2025 In zebrafish, loss-of-function of kcng4b (modulatory subunit) or kcnb1 (Kv2.1, alpha subunit) reduces locomotor activity and induces seizures with pentylenetetrazole; mutants show increased c-fos and gad2 transcripts and decreased gabra1 transcripts, indicating disrupted inhibitory neurotransmission; local field potential recordings show increased spontaneous electrical activity in the optic tectum. Zebrafish loss-of-function mutants, behavioral assays, qRT-PCR, local field potential recordings bioRxivpreprint Medium 40501962

Source papers

Stage 0 corpus · 31 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2014 Dlk1 promotes a fast motor neuron biophysical signature required for peak force execution. Science (New York, N.Y.) 59 24626931
2021 Dissociable Roles of Pallidal Neuron Subtypes in Regulating Motor Patterns. The Journal of neuroscience : the official journal of the Society for Neuroscience 49 33731450
2019 Exome sequencing in multiple sclerosis families identifies 12 candidate genes and nominates biological pathways for the genesis of disease. PLoS genetics 46 31170158
2020 Human Labor Pain Is Influenced by the Voltage-Gated Potassium Channel KV6.4 Subunit. Cell reports 31 32697988
2012 Identification of novel genes involved in migraine. Headache 30 23030542
2022 Identification of Genomic Regions and Candidate Genes Associated with Body Weight and Body Conformation Traits in Karachai Goats. Genes 26 36292658
2015 Auxiliary KCNE subunits modulate both homotetrameric Kv2.1 and heterotetrameric Kv2.1/Kv6.4 channels. Scientific reports 26 26242757
2009 Conserved negative charges in the N-terminal tetramerization domain mediate efficient assembly of Kv2.1 and Kv2.1/Kv6.4 channels. The Journal of biological chemistry 23 19717558
2015 Modulation of Closed-State Inactivation in Kv2.1/Kv6.4 Heterotetramers as Mechanism for 4-AP Induced Potentiation. PloS one 21 26505474
2018 The S6 gate in regulatory Kv6 subunits restricts heteromeric K+ channel stoichiometry. The Journal of general physiology 18 30322883
2008 Mutation of histidine 105 in the T1 domain of the potassium channel Kv2.1 disrupts heteromerization with Kv6.3 and Kv6.4. The Journal of biological chemistry 18 19074135
2022 Genome-wide association analysis of nine reproduction and morphological traits in three goat breeds from Southern China. Animal bioscience 16 35760404
2019 Kv2.1 voltage-gated potassium channels in developmental perspective. Developmental dynamics : an official publication of the American Association of Anatomists 15 31512327
2017 Targeted deletion of the Kv6.4 subunit causes male sterility due to disturbed spermiogenesis. Reproduction, fertility, and development 15 27677211
2011 Functional interactions between residues in the S1, S4, and S5 domains of Kv2.1. European biophysics journal : EBJ 12 21455829
2024 Functional properties of a disease mutation for migraine in Kv2.1/6.4 channels. Biochemical and biophysical research communications 9 39159549
2018 Altered expression of KCNG3 and KCNG4 in Hirschsprung's disease. Pediatric surgery international 9 30386900
2024 KCNG4 Genetic Variant Linked to Migraine Prevents Expression of KCNB1. International journal of molecular sciences 7 39201645
2025 A Kv2 inhibitor combination reveals native neuronal conductances consistent with Kv2/KvS heteromers. eLife 6 40423692
2024 Mutant analysis of Kcng4b reveals how the different functional states of the voltage-gated potassium channel regulate ear development. Developmental biology 6 38492873
2023 Genome-wide diversity and admixture of five indigenous cattle populations from the Tigray region of northern Ethiopia. Frontiers in genetics 6 37600659
2025 Effects of latent infection of Toxoplasma gondii strains with different genotypes on mouse behavior and brain transcripts. Parasites & vectors 3 40420177
2025 Kv2/Kv6.4 Heteromeric Potassium Channels Are Expressed in Spinal Motoneurons and Localized at C-Bouton Synapses. The European journal of neuroscience 2 40919874
2015 Expression and function of a CP339,818-sensitive K⁺ current in a subpopulation of putative nociceptive neurons from adult mouse trigeminal ganglia. Journal of neurophysiology 2 25652918
2026 A silent Kv channel subunit shapes PV neuron action potential waveform and short-term synaptic plasticity during high-frequency firing. Proceedings of the National Academy of Sciences of the United States of America 0 41632839
2026 Specialized outputs and behavioral contributions of Purkinje cell subtypes. bioRxiv : the preprint server for biology 0 42239096
2025 A Kv2 inhibitor combination reveals native neuronal conductances consistent with Kv2/KvS heteromers. bioRxiv : the preprint server for biology 0 38352561
2025 Identification and Validation of Alkaliptosis Resistance-Associated Genes in Prostate Cancer Via Transcriptome Sequencing and Prediction of Biochemical Recurrence. Molecular biotechnology 0 39760809
2025 Kv2/Kv6.4 heteromeric potassium channels are expressed in spinal motor neurons and localized at C-bouton synapses. bioRxiv : the preprint server for biology 0 40501962
2025 A silent Kv channel subunit shapes PV neuron action potential waveform and short-term synaptic plasticity during high-frequency firing. bioRxiv : the preprint server for biology 0 41279724
2024 Multiple time points of transcriptome analysis revealed altered genes involved in maintaining hibernation in the hypothalamus of Tamias sibiricus. Frontiers in neuroscience 0 39764389

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