Referenced in: none

Automatically associated channels: Kv7.1 , Kv7.2 , Kv7.3 , Kv7.4

Title: Differential tetraethylammonium sensitivity of KCNQ1-4 potassium channels.

Authors: J K Hadley, M Noda, A A Selyanko, I C Wood, F C Abogadie, D A Brown

Journal, date & volume: Br. J. Pharmacol., 2000 Feb , 129, 413-5

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/10711337

Abstract
In Shaker-group potassium channels the presence of a tyrosine residue, just downstream of the pore signature sequence GYG, determines sensitivity to tetraethylammonium (TEA). The KCNQ family of channels has a variety of amino acid residues in the equivalent position. We studied the effect of TEA on currents generated by KCNQ homomers and heteromers expressed in CHO cells. We used wild-type KCNQ1-4 channels and heteromeric KCNQ2/3 channels incorporating either wild-type KCNQ3 subunits or a mutated KCNQ3 in which tyrosine replaced threonine at position 323 (mutant T323Y). IC50 values were (mM): KCNQ1, 5.0; KCNQ2, 0.3; KCNQ3, > 30; KCNQ4, 3.0; KCNQ2 + KCNQ3, 3.8; and KCNQ2 + KCNQ3(T323Y), 0.5. While the high TEA sensitivity of KCNQ2 may be conferred by a tyrosine residue lacking in the other channels, the intermediate TEA sensitivity of KCNQ1 and KCNQ4 implies that other residues are also important in determining TEA block of the KCNQ channels.