Referenced in: none

Automatically associated channels: Kir1.1 , Kir2.1

Title: Gating of inwardly rectifying K+ channels localized to a single negatively charged residue.

Authors: B A Wible, M Taglialatela, E Ficker, A M Brown

Journal, date & volume: Nature, 1994 Sep 15 , 371, 246-9

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/8078584

Abstract
Inwardly rectifying K+ channels (IRKs) conduct current preferentially in the inward direction. This inward rectification has two components: voltage-dependent blockade by intracellular Mg2+ (Mg2+i) and intrinsic gating. Two members of this channel family, IRK1 (ref. 10) and ROMK1 (ref. 11), differ markedly in affinity for Mg2+i (ref. 12). We found that IRK1 and ROMK1 differ in voltage-dependent gating and searched for the gating structure by large-scale and site-directed mutagenesis. We found that a single amino-acid change within the putative transmembrane domain M2, aspartate (D) in IRK1 to the corresponding asparagine (N) in ROMK1, controls the gating phenotype. Mutation D172N in IRK1 produced ROMK1-like gating whereas the reverse mutation in ROMK1--N171D--produced IRK1-like gating. Thus, a single negatively charged residue seems to be a crucial determinant of gating.