Referenced in: none

Automatically associated channels: Kv11.1 , Slo1

Title: Concerted all-or-none subunit interactions mediate slow deactivation of human ether-à-go-go-related gene K+ channels.

Authors: Steven J Thomson, Angela Hansen, Michael C Sanguinetti

Journal, date & volume: J. Biol. Chem., 2014 Aug 22 , 289, 23428-36

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/25008322

Abstract
During the repolarization phase of a cardiac action potential, hERG1 K(+) channels rapidly recover from an inactivated state then slowly deactivate to a closed state. The resulting resurgence of outward current terminates the plateau phase and is thus a key regulator of action potential duration of cardiomyocytes. The intracellular N-terminal domain of the hERG1 subunit is required for slow deactivation of the channel as its removal accelerates deactivation 10-fold. Here we investigate the stoichiometry of hERG1 channel deactivation by characterizing the kinetic properties of concatenated tetramers containing a variable number of wild-type and mutant subunits. Three mutations known to accelerate deactivation were investigated, including R56Q and R4A/R5A in the N terminus and F656I in the S6 transmembrane segment. In all cases, a single mutant subunit induced the same rapid deactivation of a concatenated channel as that observed for homotetrameric mutant channels. We conclude that slow deactivation gating of hERG1 channels involves a concerted, fully cooperative interaction between all four wild-type channel subunits.