KCNG1

KCNG1 encodes Kv6.1, an electrically silent voltage-gated potassium channel α-subunit that does not form functional homomeric channels but instead co-assembles with Kv2.1 through protein-protein interactions at the amino-terminal portions of the subunits (PMID:8980147). Incorporation of Kv6.1 into Kv2.1-containing heteromers confers distinct gating: a hyperpolarizing shift in steady-state activation, markedly slowed deactivation, reduced TEA sensitivity, and altered (slowed) inactivation at strong depolarizations (PMID:8980147, PMID:9696692). Co-assembly with Kv2.1 also drives phosphorylation of Kv6.1, indicating that the heteromeric partnership controls both gating and post-translational modification of the silent subunit (PMID:41241096). Disease-associated Kv6.1 variants in the ion transport domain disrupt this regulatory partnership: the pore-helix variant W416C nearly abolishes Kv2.1 current, reduces protein levels of both subunits, and abrogates Kv6.1 phosphorylation, while L284P attenuates Kv6.1-mediated modulation of Kv2.1 inactivation (PMID:41241096). The W416C variant was identified in a calf with paradoxical myotonia congenita and associated neuromuscular and craniofacial pathology, linking KCNG1 to neuromuscular disease (PMID:34828398).

1. 1996 High

   Established that Kv6.1 is not an independent channel but a modulatory subunit, answering whether KCNG1 produces current on its own and how it acts.

   Evidence Two-electrode voltage clamp in Xenopus oocytes plus yeast two-hybrid showing N-terminal interaction with Kv2.1

   PMID:8980147

   Open questions at the time

   • Stoichiometry of Kv6.1:Kv2.1 in native heteromers not defined
   • Structural basis of the N-terminal interaction not resolved
   • Physiological tissue context of the heteromer not addressed
2. 1998 High

   Resolved how Kv6.1 reshapes Kv2.1 gating, distinguishing its inactivation effects from those of the related Kv5.1 subunit and confirming true heteromeric assembly.

   Evidence Two-electrode voltage clamp, biochemical co-assembly assay, and single-channel recordings in Xenopus oocytes

   PMID:9696692

   Open questions at the time

   • Mechanism by which Kv6.1 slows deactivation/inactivation not defined at the structural level
   • Native conductance heterogeneity not linked to defined subunit ratios
3. 2021 Low

   Implicated KCNG1 in neuromuscular disease by associating a pore-helix variant with a myotonia/neurodegeneration phenotype, raising the question of functional consequence.

   Evidence Whole-genome sequencing, variant prediction, and histopathology in a single calf

   PMID:34828398

   Open questions at the time

   • Single genetic case with no functional reconstitution to confirm causality
   • Whether the phenotype reflects a Kv2.1/Kv6.1 channel defect untested at this stage
4. 2025 Medium

   Connected disease variants to mechanism by showing they impair Kv2.1 current, subunit expression, and a newly identified Kv2.1-dependent phosphorylation of Kv6.1.

   Evidence Voltage clamp, Western blot expression analysis, and phosphorylation assays in HEK293/Xenopus expression systems

   PMID:41241096

   Open questions at the time

   • Phosphorylation site(s) and responsible kinase not identified
   • Single study; functional consequences in native tissue not established
   • Mechanism linking reduced phosphorylation to loss of current unresolved

• How Kv6.1 phosphorylation regulates heteromeric channel trafficking, stability, and gating in native neuromuscular tissue remains unresolved.
• Kinase and phosphosite controlling Kv6.1 modification unknown
• Endogenous Kv2.1/Kv6.1 channel function in affected tissues uncharacterized