Affinage

KCNH8

Voltage-gated delayed rectifier potassium channel KCNH8 · UniProt Q96L42

Length
1107 aa
Mass
123.8 kDa
Annotated
2026-06-10
25 papers in source corpus 8 papers cited in narrative 7 extracted findings
Cross-family judge vs UniProt: Affinage preferred faithfulness: 4/5 claims corpus-supported (80%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

KCNH8 (Kv12.1/Elk1) is a voltage-gated potassium channel of the Elk subfamily that shapes the intrinsic excitability of neurons, most notably setting the day-night rhythm of circadian pacemaker firing (PMID:12890647, PMID:37516908, PMID:36778242). Expressed heterologously, it produces slowly activating, voltage-dependent K+ currents that open at unusually hyperpolarized potentials (half-maximal activation near -62 mV) and assembles into heteromultimers with other Elk subfamily subunits (KCNH3, KCNH4) but not with Eag, Erg, or Kv-family channels (PMID:12890647). Channel gating is tuned by extracellular pH: external protons depolarize the conductance-voltage relationship through a pair of EAG-specific acidic residues in the voltage sensor that also govern Zn2+ sensitivity (PMID:23712551). The channel is potently activated by the gating modifier ginsenoside Rg3, which shifts voltage-dependent activation by more than -100 mV and slows deactivation, with selectivity for Elk1 over Erg and Eag channels (PMID:27502018). Functionally, Kv12-encoded current density is higher at night in suprachiasmatic nucleus neurons, and genetic disruption of Kcnh8 abolishes the day-night difference in firing by selectively raising nighttime firing rates, establishing KCNH8 as a driver of the circadian switch in pacemaker activity (PMID:37516908, PMID:36778242).

Mechanistic history

Synthesis pass · year-by-year structured walk · 5 steps
  1. 2003 High

    Established the basic biophysical identity of KCNH8 as a hyperpolarization-activated Elk-subfamily K+ channel and defined its subunit assembly rules, answering whether it forms a functional channel and with which partners.

    Evidence Heterologous expression in Xenopus oocytes with voltage-clamp and dominant-negative co-expression

    PMID:12890647

    Open questions at the time
    • Native subunit composition in neurons not determined
    • Physiological role in vivo not addressed
    • No structural basis for the hyperpolarized activation
  2. 2013 High

    Identified the molecular determinant of proton sensitivity, showing how extracellular pH modulates Kv12.1 gating via specific voltage-sensor acidic residues.

    Evidence Voltage-clamp electrophysiology with site-directed mutagenesis and Zn2+ sensitivity assays in oocytes

    PMID:23712551

    Open questions at the time
    • Physiological context of pH modulation not tested in native neurons
    • Whether the residues directly bind protons versus stabilize a conformation unresolved
  3. 2016 Medium

    Defined a selective pharmacological gating modifier, providing a tool to potentiate Kv12.1 and demonstrating subtype selectivity within the EAG superfamily.

    Evidence Two-microelectrode voltage-clamp in oocytes with concentration-response analysis and Markov gating model

    PMID:27502018

    Open questions at the time
    • Binding site on the channel not mapped
    • Single-lab result
    • In vivo or native-cell efficacy not shown
  4. 2021 Medium

    Localized Kv12.1 protein to defined brainstem chemoreceptor populations, linking the channel's intrinsic pH sensitivity to candidate respiratory chemoreception circuits.

    Evidence Immunofluorescence co-localization with Phox2b, Western blot, and qRT-PCR in NTS; protein quantification in RTN of spontaneously hypertensive rats

    PMID:33347681 PMID:33903883

    Open questions at the time
    • Functional contribution of Kv12.1 to chemoreceptor firing not established by genetic manipulation
    • RTN evidence relied on a non-selective inhibitor and protein correlation only
  5. 2023 High

    Demonstrated a causal physiological function in vivo, establishing that Kv12.1 currents drive the nighttime suppression of SCN neuron firing that underlies circadian pacemaker rhythm.

    Evidence Current-clamp and voltage-clamp from SCN neurons of Kcnh8 knockout mice, in vivo shRNA knockdown, pharmacological block, and dynamic-clamp subtraction

    PMID:36778242 PMID:37516908

    Open questions at the time
    • Molecular mechanism coupling Kv12.1 current to time-of-day signals unknown
    • Whether channel abundance or gating is clock-regulated not determined

Open questions

Synthesis pass · forward-looking unresolved questions
  • How KCNH8 expression and gating are regulated to produce its tissue-specific physiological roles remains open.
  • Transcriptional regulation unresolved — a Wnt/β-catenin link in thalamic neurons was indirect and direct promoter binding was negative by ChIP
  • No structural model of the channel
  • Functional role in chemoreception not proven genetically

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0005215 transporter activity 2 GO:0140299 molecular sensor activity 1
Localization
GO:0005886 plasma membrane 1
Pathway
R-HSA-112316 Neuronal System 1 R-HSA-9909396 Circadian clock 1
Partners
KCNH3KCNH4

Evidence

Reading pass · 7 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2003 KCNH8 (Elk1/Kv12.1) encodes slowly activating, voltage-dependent K+ currents that open at hyperpolarized potentials (half-maximal activation at -62 mV) when expressed in Xenopus oocytes. Co-expression with dominant-negative KCNH8, KCNH3, or KCNH4 suppressed KCNH8 currents, demonstrating that Elk subfamily channels can form heteromultimers with each other. KCNH8 subunits could not form heteromultimers with Eag, Erg, or Kv family K+ channels. Heterologous expression in Xenopus oocytes, voltage-clamp electrophysiology, dominant-negative co-expression experiments American journal of physiology. Cell physiology High 12890647
2013 External acidification inhibits voltage activation of Kv12.1 (KCNH8/Elk1) by depolarizing the conductance-voltage relationship. This pH sensitivity is mediated by a pair of EAG-specific acidic residues in the voltage sensor; individual neutralization mutations of these residues greatly reduced the pH response in Kv12.1. External protons also reduce the sensitivity of Kv12.1 to Zn2+, suggesting the acidic residues form the proton-binding site or hold the voltage sensor in a pH-sensitive conformation. Voltage-clamp electrophysiology in Xenopus oocytes, site-directed mutagenesis of voltage sensor acidic residues, divalent cation (Zn2+) sensitivity assays The Journal of general physiology High 23712551
2016 Ginsenoside Rg3 acts as a gating modifier of Kv12.1 (ELK1/KCNH8), shifting the half-point of voltage-dependent activation by more than -100 mV (EC50 = 197 nM) and slowing channel deactivation. This effect is far more potent on ELK1 than on ERG1, ERG3, or EAG1 channels. Two-microelectrode voltage-clamp in Xenopus laevis oocytes, Markov model simulation of gating Molecular pharmacology Medium 27502018
2023 Kv12.1 (KCNH8)-encoded K+ channels drive the nighttime decrease in repetitive firing rates of SCN (suprachiasmatic nucleus) neurons. Targeted disruption of Kcnh8 (Kv12.1-/-) eliminated the day-night difference in mean repetitive firing rates by specifically elevating nighttime firing rates to daytime levels. Voltage-clamp experiments showed Kv12-encoded current densities are higher at night than during the day in WT SCN neurons. Pharmacological block and dynamic-clamp subtraction of Kv12 currents also selectively increased nighttime firing rates. Current-clamp recordings from SCN neurons in Kv12.1-/- knockout mice, in vivo shRNA knockdown, voltage-clamp electrophysiology, pharmacological block, dynamic-clamp subtraction The Journal of general physiology High 36778242 37516908
2021 Kv12.1 (Kv12.1/KCNH8) protein is expressed in Phox2b-expressing neurons in the nucleus tractus solitarii (NTS) of mice, where Kv12.1 mRNA is the most abundantly expressed Kv12 family member. This co-localization provides molecular evidence for a role of Kv12.1 in pH sensitivity of NTS respiratory chemoreceptor neurons. Immunofluorescence staining, Western blot, quantitative RT-PCR Sheng li xue bao : [Acta physiologica Sinica] Medium 33903883
2021 Kv12.1 (KCNH8) protein is elevated in the retrotrapezoid nucleus (RTN) of spontaneously hypertensive rats (SHRs), correlating with augmented CO2-stimulated cardiorespiratory responses. The finding that RTN neurons are involved in amplified hypercapnic responses in SHRs is associated with higher protein levels of pH-sensitive channels including Kv12.1 in this nucleus. Protein quantification by Western blot in RTN tissue, genetic ablation of RTN neurons, pharmacological inhibition with clofilium (unselective TASK-2 inhibitor) The Journal of physiology Low 33347681
2012 KCNH8 expression in thalamic neurons appears to be regulated by β-catenin (Wnt/β-catenin pathway), as removal of nuclear β-catenin from thalamic neurons by Axin2 reduced KCNH8 (Kcnh8) expression. However, direct binding of β-catenin to the regulatory sequences of Kcnh8 could not be confirmed by chromatin immunoprecipitation. Custom PCR arrays in rat forebrain, in vitro neuronal β-catenin knockdown with Axin2, chromatin immunoprecipitation (negative result for direct binding) BMC genomics Low 23157480

Source papers

Stage 0 corpus · 25 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2010 Genomic predictors of the maximal O₂ uptake response to standardized exercise training programs. Journal of applied physiology (Bethesda, Md. : 1985) 320 21183627
2012 Molecular subtyping of primary prostate cancer reveals specific and shared target genes of different ETS rearrangements. Neoplasia (New York, N.Y.) 62 22904677
2003 Distribution and functional properties of human KCNH8 (Elk1) potassium channels. American journal of physiology. Cell physiology 52 12890647
2009 DNA hypermethylation of tumors from non-small cell lung cancer (NSCLC) patients is associated with gender and histologic type. Lung cancer (Amsterdam, Netherlands) 51 19945765
2017 Genome-wide association analysis for chronic venous disease identifies EFEMP1 and KCNH8 as susceptibility loci. Scientific reports 48 28374850
2012 Novel β-catenin target genes identified in thalamic neurons encode modulators of neuronal excitability. BMC genomics 41 23157480
2021 Genomic Basis of Striking Fin Shapes and Colors in the Fighting Fish. Molecular biology and evolution 32 33871625
2021 Rare variant analysis in eczema identifies exonic variants in DUSP1, NOTCH4 and SLC9A4. Nature communications 30 34785669
2013 External pH modulates EAG superfamily K+ channels through EAG-specific acidic residues in the voltage sensor. The Journal of general physiology 30 23712551
2015 Concurrent Mutations in ATM and Genes Associated with Common γ Chain Signaling in Peripheral T Cell Lymphoma. PloS one 25 26536348
2020 The Developmental and Genetic Architecture of the Sexually Selected Male Ornament of Swordtails. Current biology : CB 22 33275891
2011 Hypermethylation of CCND2 May Reflect a Smoking-Induced Precancerous Change in the Lung. Journal of oncology 12 21577262
2023 Kv12-encoded K+ channels drive the day-night switch in the repetitive firing rates of SCN neurons. The Journal of general physiology 11 37516908
2022 Identification of Thrombosis-Related Genes in Patients with Advanced Gastric Cancer: Data from AGAMENON-SEOM Registry. Biomedicines 11 35052827
2025 Largest-Scale Genomic Resource Reconstructing the Genetic Origin, Population Structure, and Biological Adaptations of the Hui People. Molecular biology and evolution 9 41047750
2019 Next-Generation Sequencing Profiles of the Methylome and Transcriptome in Peripheral Blood Mononuclear Cells of Rheumatoid Arthritis. Journal of clinical medicine 9 31443559
2024 Voltage-gated ion channels are expressed in the Malpighian tubules and anal papillae of the yellow fever mosquito (Aedes aegypti), and may regulate ion transport during salt and water imbalance. The Journal of experimental biology 6 38197515
2016 Ginsenoside Rg3, a Gating Modifier of EAG Family K+ Channels. Molecular pharmacology 6 27502018
2021 Genetic Polymorphisms Related to VO2max Adaptation Are Associated With Elite Rugby Union Status and Competitive Marathon Performance. International journal of sports physiology and performance 5 34088882
2021 Contribution of retrotrapezoid nucleus neurons to CO2 -amplified cardiorespiratory activity in spontaneously hypertensive rats. The Journal of physiology 4 33347681
2024 Discovery of a Novel Shared Variant Among RTEL1 Gene and RTEL1-TNFRSF6B lncRNA at Chromosome 20q13.33 in Familial Progressive Myoclonus Epilepsy. International journal of genomics 1 39156922
2024 Deconvolution of cell-type-associated markers predictive of response to neoadjuvant radiotherapy. Computational biology and chemistry 1 39520737
2023 Kv12-Encoded K + Channels Drive the Day-Night Switch in the Repetitive Firing Rates of SCN Neurons. bioRxiv : the preprint server for biology 1 36778242
2026 Genome-Wide Association Study of Body Mass Index in a Commercial Landrace × Yorkshire Crossbred Pig Population. Veterinary sciences 0 41600740
2021 The Kv12 voltage-gated K+ channels are expressed in the Phox2b-expressing neurons in the nucleus tractus solitarii in mice. Sheng li xue bao : [Acta physiologica Sinica] 0 33903883

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