KV7.4 channels
| Channel name | KV7.4 |
| Description | Voltage-gated potassium channel, delayed rectifier |
| Other names | None |
| Molecular information | Human: 695aa, NM_004700 (transcript variant 1), chr. 1p34, KCNQ4,1 GeneID: 9132, PMID: 100254091 |
| Mouse: 724aa, XM_143960 (predicted), chr. 4 | |
| Rat: AF249748 (partial coding sequence) | |
| Associated subunits | KCNQ32 |
| Functional assays | Voltage-clamp |
| Current | IK,n |
| Conductance | Not established |
| Ion selectivity | K+ |
| Activation | Va = 10 mV |
| Inactivation | Not established |
| Activators | Retigabine (1 μM)3; BMS204352 (1 μM)3 |
| Gating inhibitors | None |
| Blockers | Tetraethyammonium (3 mM),4 linopirdine (14 μM),5 XE991 (5 μM),5 bepridil (9.4 μM)5 |
| Radioligands | None |
| Channel distribution | Cochlea (outer hair cells), placenta, vestibular organs (type 1 hair cells), brainstem auditory nuclei |
| Physiological functions | Mediates potassium efflux from outer hair cells1,6 |
| Mutations and pathophysiology | Mutations in KCNQ4 cause autosomal dominant nonsyndromic deafness type 2 (DFNA2)1,6 |
| Pharmacological significance | Anticonvulsants (activators) |
aa, amino acids; chr., chromosome; XE991, 10,10-bis(pyridin-4-ylmethyl)anthracen-9-one; BMS204352, 3-(5-chloro-2-methoxy-phenyl)-3-fluoro-6-(trifluoromethyl)-1H-indol-2- one.
↵1. Kubisch C, Schroeder BC, Friedrich T, Lutjohann B, El-Amraoui A, Marlin S, Petit C, and Jentsch TJ (1999) KCNQ4, a novel potassium channel expressed in sensory outer hair cells, is mutated in dominant deafness. Cell 96:437-446
↵2. Schroeder BC, Waldegger S, Fehr S, Bleich M, Warth R, Greger R, and Jentsch TJ (2000) A constitutively open potassium channel formed by KCNQ1 and KCNE3. Nature (Lond) 403:196-199
↵3. Schroder RL, Jespersen T, Christophersen P, Strobaek D, Jensen BS, and Olesen SP (2001) KCNQ4 channel activation by BMS-204352 and retigabine. Neuropharmacology 40:888-898
↵4. Hadley JK, Noda M, Selyanko AA, Wood IC, Abogadie FC, and Brown DA (2000) Differential tetraethylammonium sensitivity of KCNQ1—4 potassium channels. Br J Pharmacol 129:413-415
↵5. Sogaard R, Ljungstrom T, Pedersen KA, Olesen SP, and Jensen BS (2001) KCNQ4 channels expressed in mammalian cells: functional characteristics and pharmacology. Am J Physiol 280:C859-C866
↵6. Kharkovets T, Hardelin JP, Safieddine S, Schweizer M, El-Amraoui A, Petit C, and Jentsch TJ (2000) KCNQ4, a K+ channel mutated in a form of dominant deafness, is expressed in the inner ear and the central auditory pathway. Proc Natl Acad Sci USA 97:4333-4338