Extracellular K+ and Ba2+ mediate voltage-dependent inactivation of the outward-rectifying K+ channel encoded by the yeast gene TOK1

Vergani, Paola and Miosga, Thomas and Jarvis, Simon M. and Blatt, Michael R. (1997) Extracellular K+ and Ba2+ mediate voltage-dependent inactivation of the outward-rectifying K+ channel encoded by the yeast gene TOK1. FEBS Letters, 405 (3). pp. 337-344. ISSN 0014-5793. (The full text of this publication is not available from this repository)

The full text of this publication is not available from this repository. (Contact us about this Publication)
Official URL
http://dx.doi.org/10.1016/S0014-5793(97)00211-1

Abstract

Gating of the yeast K+ channel encoded by the Saccharomyces cerevisiae gene TOK1, unlike other outward-rectifying K+ channels that have been cloned, is promoted by membrane voltage (inside positive-going) and repressed by extracellular K+. When expressed in Xenopus laevis oocytes, the TOK1p current rectified strongly outward, its activation shifting in parallel with the K+ equilibrium potential when the external K+ concentration ([K+](0)) was increased above 3 mM. Analysis of the TOK1p current indicated that two kinetic components contributed to the conductance and the voltage sensitivity of the conductance. By contrast, the [K+](0) sensitivity of the current was accommodated entirely within the slow-relaxing component; it was diminished near 1 mM [K+](0), and at submillimolar concentrations the voltage dependence of the TOK1p conductance was insensitive to [K+](0). External Rb+, the K+ channel blockers Cs+ and Ba2+ - but not Na+, Ca2+ or Mg2+ - substituted for K+ in control of TOK1p activation, indicating a specificity in cation interaction with the TOK1p gate. These and additional results indicate that external K+ acts as a ligand to inactivate the TOK1p channel, and they implicate a gating process mediated by a single cation binding site within the membrane electric field, but distinct from the permeation pathway. (C) 1997 Federation of European Biochemical Societies.

Item Type: Article
Subjects: Q Science > QR Microbiology
Q Science > QP Physiology (Living systems) > QP506 Molecular biology
Divisions: Faculties > Science Technology and Medical Studies > School of Biosciences
Depositing User: T.J. Sango
Date Deposited: 05 May 2009 07:37
Last Modified: 24 Apr 2014 07:58
Resource URI: http://kar.kent.ac.uk/id/eprint/18006 (The current URI for this page, for reference purposes)
  • Depositors only (login required):