| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
Department of Pharmacology and MRC Centre for Synaptic Plasticity, University of Bristol, Bristol, United Kingdom
Correspondence: Address reprint requests to Neil V. Marrion, Dept. of Pharmacology and MRC Centre for Synaptic Plasticity, School of Medical Sciences, University of Bristol, University Walk, Bristol BS8 1TD, UK. Tel.: 44-117-954-6405; Fax: 44-117-925-0168; E-mail: n.v.marrion{at}bristol.ac.uk.
Heteromeric KCNQ2/3 potassium channels are thought to underlie the M-current, a subthreshold potassium current involved in the regulation of neuronal excitability. KCNQ channel subunits are structurally unique, but it is unknown whether these structural differences result in unique conduction properties. Heterologously expressed KCNQ2/3 channels showed a permeation sequence of 
while showing a conduction sequence of 
A differential contribution of component subunits to the properties of heteromeric KCNQ2/3 channels was demonstrated by studying homomeric KCNQ2 and KCNQ3 channels, which displayed contrasting ionic selectivities. KCNQ2/3 channels did not exhibit an anomalous mole-fraction effect in mixtures of K+ and Rb+. However, extreme voltage-dependence of block by external Cs+ was indicative of multi-ion pore behavior. Block of KCNQ2/3 channels by external Ba2+ ions was voltage-independent, demonstrating unusual ionic occupation of the outer pore. Selectivity properties and block of KCNQ2 were altered by mutation of outer pore residues in a manner consistent with the presence of multiple ion-binding sites. KCNQ2/3 channel deactivation kinetics were slowed exclusively by Rb+, whereas activation of KCNQ2/3 channels was altered by a variety of external permeant ions. These data indicate that KCNQ2/3 channels are multi-ion pores which exhibit distinctive mechanisms of ion conduction and gating.
This article has been cited by other articles:
 |
|
 |
|
  C. Gunay, J. R. Edgerton, and D. Jaeger Channel Density Distributions Explain Spiking Variability in the Globus Pallidus: A Combined Physiology and Computer Simulation Database Approach J. Neurosci., July 23, 2008; 28(30): 7476 - 7491. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 I. R. Boulet, A. J. Labro, A. L. Raes, and D. J. Snyders Role of the S6 C-terminus in KCNQ1 channel gating J. Physiol., December 1, 2007; 585(2): 325 - 337. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. Zhang Isolation and characterization of IKr in cardiac myocytes by Cs+ permeation Am J Physiol Heart Circ Physiol, March 1, 2006; 290(3): H1038 - H1049. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. Etxeberria, I. Santana-Castro, M. P. Regalado, P. Aivar, and A. Villarroel Three Mechanisms Underlie KCNQ2/3 Heteromeric Potassium M-Channel Potentiation J. Neurosci., October 13, 2004; 24(41): 9146 - 9152. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
