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

• Published in: Nature (London) 1994-09, Vol.371 (6494), p.246-249
• Main Authors: Wible, Barbara A, Taglialatela, Maurizio, Ficker, Eckhard, Brown, Arthur M
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; Biochemistry; Biological and medical sciences; Cell membranes. Ionic channels. Membrane pores; Cell structures and functions; Cells, Cultured; Fundamental and applied biological sciences. Psychology; Humanities and Social Sciences; Humans; Ion Channel Gating; letter; Magnesium - metabolism; Membrane Potentials; Molecular and cellular biology; Molecular Sequence Data; multidisciplinary; Mutagenesis, Site-Directed; Mutation; Oocytes; Potassium; Potassium Channels - genetics; Potassium Channels - metabolism; Potassium Channels, Inwardly Rectifying; Recombinant Fusion Proteins - genetics; Recombinant Fusion Proteins - metabolism; Science; Science (multidisciplinary); Xenopus
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/371246a0

INWARDLY rectifying K + channels (IRKs) conduct current preferentially in the inward direction. This inward rectification has two components: voltage-dependent blockade by intracellular Mg 2+ (Mg i 2+ ) l–7 and intrinsic gating 8,9 . Two members of this channel family, IRK1 (ref. 10) and ROMK1 (ref. 11), differ markedly in affinity for Mg i 2+ (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 ROMKl-like gating whereas the reverse mutation in ROMK1—N17ID—produced IRKl-like gating. Thus, a single negatively charged residue seems to be a crucial determinant of gating.