The Journal of General Physiology
Avanti Polar Lipids, Inc.
  Home | Help | Feedback | Subscriptions | Archive | Search | Table of Contents
This Article
Right arrow Full Text (PDF, 1233K)
Right arrow Alert me when this article is cited
Services
Right arrow Email this article
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new content in the JGP
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via CrossRef
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Franciolini, F.
Right arrow Articles by Nonner, W.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Franciolini, F.
Right arrow Articles by Nonner, W.
Social Bookmarking
Add to CiteULike   Add to Complore   Add to Connotea   Add to Del.icio.us   Add to Digg   Add to Reddit   Add to Technorati  
What's this?

The Journal of General Physiology, Vol 104, 725-746, Copyright © 1994 by The Rockefeller University Press

ARTICLES

A multi-ion permeation mechanism in neuronal background chloride channels

F Franciolini and W Nonner
Department of Physiology and Biophysics, University of Miami, Florida 33101.

Unitary current/voltage relationships of background Cl channels of rat hippocampal neurons were determined for varied gradients and absolute concentrations of NaCl. The channels revealed permeabilities for both Cl and Na ions. A hyperlinear increase of unitary conductance, observed for a symmetrical increase of salt concentration from 300 and 600 mM, indicated a multi-ion permeation mechanism. A variety of kinetic models of permeation were tested against the experimental current/voltage relationships. Models involving a pore occupied by mixed complexes of up to five ions were necessary to reproduce all measurements. A minimal model included four equilibrium states and four rate-limiting transitions, such that the empty pore accepts first an anion and then can acquire one or two cation/anion pairs. Three transport cycles are formed: a slow anion cycle (between the empty and single-anion states), a slow cation cycle (between the one- and three-ion states), and a fast anion cycle (between the three- and five-ion states). Thus, permeant anions are required for cation permeation, and several bound anions and cations promote a high rate of anion permeation. The optimized free- energy and electrical charge parameters yielded a self-consistent molecular interpretation, which can account for the particular order in which the pore accepts ions from the solutions. Although the model describes the mixed anion/cation permeability of the channel observed at elevated concentrations, it predicts a high selectivity for Cl anion at physiological ionic conditions.
Add to CiteULike CiteULike   Add to Complore Complore   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us   Add to Digg Digg   Add to Reddit Reddit   Add to Technorati Technorati    What's this?


This article has been cited by other articles:


Home page
 Biophys. JHome page
S. Sugiharto, T. M. Lewis, A. J. Moorhouse, P. R. Schofield, and P. H. Barry
Anion-Cation Permeability Correlates with Hydrated Counterion Size in Glycine Receptor Channels
Biophys. J., November 15, 2008; 95(10): 4698 - 4715.
[Abstract] [Full Text] [PDF]

Home page
 JGPHome page
A. L. Harris
Connexin Specificity of Second Messenger Permeation: Real Numbers At Last
J. Gen. Physiol., March 31, 2008; 131(4): 287 - 292.
[Full Text] [PDF]

Home page
 Am. J. Physiol. Cell Physiol.Home page
R. J. Thompson, H. C. S. R. Akana, C. Finnigan, K. E. Howell, and J. H. Caldwell
Anion channels transport ATP into the Golgi lumen
Am J Physiol Cell Physiol, February 1, 2006; 290(2): C499 - C514.
[Abstract] [Full Text] [PDF]


  Home | Help | Feedback | Subscriptions | Archive | Search | Table of Contents