KCNQ4
Domain
Each channel subunit contains six transmembrane segments (S1-S6) with S1-S4 forming one voltage sensing domain (VSD) and S5-S6 contributing to form one quarter of an interlocking pore-forming domain (PD).
The CALM binding domains correspond to the first two membrane-proximal helical regions that interact with a single calmodulin/CALM molecule forming a clamp-like structure (PubMed:29429937, PubMed:34767770). CALM N-terminus binds to the second helix in both calcium-free and calcium-bound forms and regulates channel trafficking. CALM C-terminus binds to the first helice in calcium-free form; this interaction is disrupted by calcium binding which regulates channel electrophysiological activity (PubMed:29429937).
The C-terminal assembly domain carries the major determinants of tetramerization and subunit assembly specificity. Its coiled-coil region is four-stranded.
Function
Pore-forming subunit of the voltage-gated potassium (Kv) channel involved in the regulation of sensory cells excitability in the cochlea (PubMed:10025409, PubMed:34767770). KCNQ4/Kv7.4 channel is composed of 4 pore-forming subunits assembled as tetramers (PubMed:34767770). Promotes the outflow of potassium ions in the repolarization phase of action potential which plays a role in regulating membrane potential of excitable cells (PubMed:10025409, PubMed:11245603, PubMed:34767770). The channel conducts a slowly activating and deactivating current (PubMed:10025409, PubMed:11245603). Current often shows some inward rectification at positive potentials (PubMed:10025409). Channel may be selectively permeable in vitro to other cations besides potassium, in decreasing order of affinity K(+) = Rb(+) > Cs(+) > Na(+) (PubMed:10025409). Important for normal physiological function of inner ear such as sensory perception of sound (PubMed:10025409, PubMed:10369879).
Involvement in disease
Deafness, autosomal dominant, 2A
DFNA2A
A form of non-syndromic sensorineural hearing loss. Sensorineural deafness results from damage to the neural receptors of the inner ear, the nerve pathways to the brain, or the area of the brain that receives sound information.
None
The disease is caused by variants affecting the gene represented in this entry.
Sequence Similarities
Belongs to the potassium channel family. KQT (TC 1.A.1.15) subfamily. Kv7.4/KCNQ4 sub-subfamily.
Tissue Specificity
Expressed in the outer, but not the inner, sensory hair cells of the cochlea (PubMed:10025409). Slightly expressed in heart, brain and skeletal muscle (PubMed:10025409).
Cellular localization
- Basal cell membrane
- Multi-pass membrane protein
- Situated at the basal membrane of cochlear outer hair cells.
Alternative names
Potassium voltage-gated channel subfamily KQT member 4, KQT-like 4, Potassium channel subunit alpha KvLQT4, Voltage-gated potassium channel subunit Kv7.4, KCNQ4