Mutations in the pore regions of the yeast K+ channel YKC1 affect gating by extracellular K+

Vergani, P. and Hamilton, D. and Jarvis, S.M. and Blatt, M.R. (1998) Mutations in the pore regions of the yeast K+ channel YKC1 affect gating by extracellular K+. Embo Journal, 17 (24). pp. 7190-7198. ISSN 0261-4189. (The full text of this publication is not available from this repository)

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Official URL
http://dx.doi.org/10.1093/emboj/17.24.7190

Abstract

The product of the Saccharomyces cerevisiae K+-channel gene YKC1 includes two pore-loop sequences that are thought to form the hydrophilic lining of the pore. Gating of the channel is promoted by membrane depolarization and is regulated by extracellular K+ concentration ([K+](o)) both in the yeast and when expressed in Xenopus oocytes, Analysis of the wild-type current now shows that: (i) [K+](o) suppresses a very slowly relaxing component, accelerating activation; (ii) [K+](o) slows deactivation in a dose-dependent fashion; and (iii) Rb+, Cs+ and, to a lesser extent, Na+ substitute for K+ in its action on gating, We have identified single residues, L293 and A428, at equivalent positions within the two pore loops that affect the [K+](o) sensitivity. Substitution of these residues gave channels with reduced sensitivity to [K+](o) in macroscopic current kinetics and voltage dependence, but had only minor effects on selectivity among alkali cations in gating and on single-channel conductance, In some mutants, activation was slowed sufficiently to confer a sigmoidicity to current rise at low [K+](o). The results indicate that these residues are involved in [K+](o) sensing. Their situation close to the permeation pathway points to an interaction between gating and permeation.

Item Type: Article
Uncontrolled keywords: ion permeation; outward-rectifier K+ channel; potassium-dependent gating; Saccharomyces cerevisiae; site-directed mutagenesis
Subjects: Q Science
Q Science > QP Physiology (Living systems) > QP517 Biochemistry
Q Science > QP Physiology (Living systems) > QP506 Molecular biology
Divisions: Faculties > Science Technology and Medical Studies > School of Biosciences
Depositing User: Tara Puri
Date Deposited: 01 Jun 2009 19:19
Last Modified: 01 Jun 2009 19:19
Resource URI: http://kar.kent.ac.uk/id/eprint/17230 (The current URI for this page, for reference purposes)
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