The Journal of General Physiology
Axon Instruments microelectrode amplifiers
  Home | Help | Feedback | Subscriptions | Archive | Search | Table of Contents
Published online June 11, 2007
doi:10.1085/jgp.200609716
The Journal of General Physiology, Vol. 130, No. 1, 55-70
The Rockefeller University Press, 0022-1295 $30.00
© 2007 Anantharam et al.
This Article
Right arrow Full Text
Right arrow Full Text (PDF, 795K)
Right arrow PPT slides of all figures
Right arrow Alert me when this article is cited
Right arrow Citation Map
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 Anantharam, A.
Right arrow Articles by Palmer, L. G.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Anantharam, A.
Right arrow Articles by Palmer, L. G.
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?

ARTICLE

 Determination of Epithelial Na+ Channel Subunit Stoichiometry from Single-Channel Conductances



Arun Anantharam1,2 and Lawrence G. Palmer2

1 Graduate Program in Neuroscience and 2 Department of Physiology and Biophysics, Weill Medical College of Cornell University, New York, NY 10021

Correspondence to Lawrence G. Palmer: lgpalm{at}med.cornell.edu

The epithelial Na+ channel (ENaC) is a multimeric membrane protein consisting of three subunits, {alpha}, ß, and {gamma}. The total number of subunits per functional channel complex has been described variously to follow either a tetrameric arrangement of 2{alpha}:1ß:1{gamma} or a higher-ordered stoichiometry of 3{alpha}:3ß:3{gamma}. Therefore, while it is clear that all three ENaC subunits are required for full channel activity, the number of the subunits required remains controversial. We used a new approach, based on single-channel measurements in Xenopus oocytes to address this issue. Individual mutations that alter single-channel conductance were made in pore-lining residues of ENaC {alpha}, ß, or {gamma} subunits. Recordings from patches in oocytes expressing a single species, wild type or mutant, of {alpha}, ß, and {gamma} showed a well-defined current transition amplitude with a single Gaussian distribution. When cRNAs for all three wild-type subunits were mixed with an equimolar amount of a mutant {alpha}-subunit (either S589D or S592T), amplitudes corresponding to pure wild-type or mutant conductances could be observed in the same patch, along with a third intermediate amplitude most likely arising from channels with at least one wild-type and at least 1 mutant {alpha}-subunit. However, intermediate or hybrid conductances were not observed with coexpression of wild-type and mutant ßG529A or {gamma}G534E subunits. Our results support a tetrameric arrangement of ENaC subunits where 2{alpha}, 1ß, and 1{gamma} come together around central pore.

Abbreviations used in this paper: ENaC, epithelial Na+ channel; wt, wild type.


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
 Am. J. Physiol. Gastrointest. Liver Physiol.Home page
M. Hatch and R. W. Freel
Increased colonic sodium absorption in rats with chronic renal failure is partially mediated by AT1 receptor agonism
Am J Physiol Gastrointest Liver Physiol, August 1, 2008; 295(2): G348 - G356.
[Abstract] [Full Text] [PDF]

Home page
 JCBHome page
A. Anantharam and L. G. Palmer
Determination of Epithelial Na+ Channel Subunit Stoichiometry from Single-channel Conductances
J. Cell Biol., October 3, 2007; 178(1): i4 - i4.
[Full Text]


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