The Journal of General Physiology
Cell MicroControls
  Home | Help | Feedback | Subscriptions | Archive | Search | Table of Contents
Published 1 December 2001. doi:10.1085/jgp.118.6.639
This Article
Right arrow Full Text
Right arrow Full Text (PDF, 269K)
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 CrossRef
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Gómez-Lagunas, F.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Gómez-Lagunas, F.
Social Bookmarking
Add to CiteULike   Add to Complore   Add to Connotea   Add to Del.icio.us   Add to Digg   Add to Facebook   Add to Reddit   Add to Technorati   Add to Twitter  
What's this?
© The Rockefeller University Press, 0022-1295/2001//639/ $5.00
Journal of General Physiology, Volume 118, Number 6, 2001

Original Article

Na+ Interaction with the Pore of Shaker B K+ Channels

Zero and Low K+ Conditions



Froylán Gómez-Lagunasa,b

a Departamento de Fisiología, Facultad de Medicina, UNAM, Universitaria, México City 04510, México
b Departamento de Reconocimiento Molecular y Biologia Estructural, Instituto de Biotecnología, UNAM, Cuernavaca, Morelos 62250, México
Departamento de Fisiología, Facultad de Medicina, UNAM, Universitaria, México City 04510, México.52-73-172388

froylan{at}ibt.unam.mx

The Shaker B K+ conductance (GK) collapses (in a reversible manner) if the membrane is depolarized and then repolarized in, 0 K+, Na+-containing solutions (Gómez-Lagunas, F. 1997. J. Physiol. 499:3–15; Gómez-Lagunas, F. 1999. Biophys. J. 77:2988–2998). In this work, the role of Na+ ions in the collapse of GK in 0-K+ solutions, and in the behavior of the channels in low K+, was studied. The main findings are as follows. First, in 0-K+ solutions, the presence of Na+ ions is an important factor that speeds the collapse of GK. Second, external Na+ fosters the drop of GK by binding to a site with a Kd = 3.3 mM. External K+ competes, in a mutually exclusive manner, with Nao+ for binding to this site, with an estimated Kd = 80 µM. Third, NMG and choline are relatively inert regarding the stability of GK; fourth, with [Ko+] = 0, the energy required to relieve Nai+ block of Shaker (French, R.J., and J.B. Wells. 1977. J. Gen. Physiol. 70:707–724; Starkus, J.G., L. Kuschel, M. Rayner, and S. Heinemann. 2000. J. Gen. Physiol. 110:539–550) decreases with the molar fraction of Nai+ (XNa,i), in an extent not accounted for by the change in {Delta}µNa. Finally, when XNa,i = 1, GK collapses by the binding of Nai+ to two sites, with apparent Kds of 2 and 14.3 mM.

Key Words: K+ affinity • Na+ block • conductance • selectivity • zero K+

© 2001 The Rockefeller University Press


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 Facebook Facebook   Add to Reddit Reddit   Add to Technorati Technorati   Add to Twitter Twitter    What's this?




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