The Journal of General Physiology
Cell MicroControls
  Home | Help | Feedback | Subscriptions | Archive | Search | Table of Contents

Published 16 April 2001. doi:10.1085/jgp.117.5.373
This Article
Right arrow Full Text
Right arrow Full Text (PDF, 213K)
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 Thompson, J.
Right arrow Articles by Begenisich, T.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Thompson, J.
Right arrow Articles by Begenisich, T.
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 Rockefeller University Press, 0022-1295/2001/5/373/ $5.00
The Journal of General Physiology, Volume 117, Number 5, May 1, 2001 373-384


Original Article

Affinity and Location of an Internal K+ Ion Binding Site in Shaker K Channels

Jill Thompsona and Ted Begenisicha
a Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, New York 14642

Correspondence to: Ted Begenisich, Department of Pharmacology and Physiology, Box 711, University of Rochester Medical Center, Rochester, NY 14642. Fax:(716) 273-2652 E-mail:ted_begenisich{at}URMC.rochester.edu.

We have examined the interaction between TEA and K+ ions in the pore of Shaker potassium channels. We found that the ability of external TEA to antagonize block of Shaker channels by internal TEA depended on internal K+ ions. In contrast, this antagonism was independent of external K+ concentrations between 0.2 and 40 mM. The external TEA antagonism of internal TEA block increased linearly with the concentration of internal K+ ions. In addition, block by external TEA was significantly enhanced by increases in the internal K+ concentration. These results suggested that external TEA ions do not directly antagonize internal TEA, but rather promote increased occupancy of an internal K+ site by inhibiting the emptying of that site to the external side of the pore. We found this mechanism to be quantitatively consistent with the results and revealed an intrinsic affinity of the site for K+ ions near 65 mM located ~7% into the membrane electric field from the internal end of the pore. We also found that the voltage dependence of block by internal TEA was influenced by internal K+ ions. The TEA site (at 0 internal K+) appeared to sense ~5% of the field from the internal end of the pore (essentially colocalized with the internal K+ site). These results lead to a refined picture of the number and location of ion binding sites at the inner end of the pore in Shaker K channels.

Key Words: ion channels, ion permeation, voltage-clamp, tetraethylammonium


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
JGPHome page
J. Thompson and T. Begenisich
Two Stable, Conducting Conformations of the Selectivity Filter in Shaker K+ Channels
J. Gen. Physiol., May 31, 2005; 125(6): 619 - 629.
[Abstract] [Full Text] [PDF]


Home page
Mol. Pharmacol.Home page
S. J. Pitt, J. Martinez-Pinna, E. A. Barnard, and M. P. Mahaut-Smith
Potentiation of P2Y Receptors by Physiological Elevations of Extracellular K+ via a Mechanism Independent of Ca2+ Influx
Mol. Pharmacol., May 1, 2005; 67(5): 1705 - 1713.
[Abstract] [Full Text] [PDF]


Home page
Plant CellHome page
Y.-H. Su, H. North, C. Grignon, J.-B. Thibaud, H. Sentenac, and A.-A. Very
Regulation by External K+ in a Maize Inward Shaker Channel Targets Transport Activity in the High Concentration Range
PLANT CELL, May 1, 2005; 17(5): 1532 - 1548.
[Abstract] [Full Text] [PDF]


Home page
JGPHome page
J. Thompson and T. Begenisich
External TEA Block of Shaker K+ Channels Is Coupled to the Movement of K+ Ions within the Selectivity Filter
J. Gen. Physiol., July 28, 2003; 122(2): 239 - 246.
[Abstract] [Full Text] [PDF]


Home page
J. Physiol.Home page
J. Thompson and T. Begenisich
Functional identification of ion binding sites at the internal end of the pore in Shaker K+ channels
J. Physiol., May 15, 2003; 549(1): 107 - 120.
[Abstract] [Full Text] [PDF]


Home page
JGPHome page
P. Andalib, M. J. Wood, and S. J. Korn
Control of Outer Vestibule Dynamics and Current Magnitude in the Kv2.1 Potassium Channel
J. Gen. Physiol., October 29, 2002; 120(5): 739 - 755.
[Abstract] [Full Text] [PDF]


Home page
JGPHome page
S. Ding and R. Horn
Tail End of the S6 Segment: Role in Permeation in Shaker Potassium Channels
J. Gen. Physiol., June 24, 2002; 120(1): 87 - 97.
[Abstract] [Full Text] [PDF]


Home page
JGPHome page
Z. Varga, M. D. Rayner, and J. G. Starkus
Cations Affect the Rate of Gating Charge Recovery in Wild-type and W434F Shaker Channels through a Variety of Mechanisms
J. Gen. Physiol., April 29, 2002; 119(5): 467 - 486.
[Abstract] [Full Text] [PDF]


Home page
JGPHome page
Z. Varga, M. D. Rayner, and J. G. Starkus
Cations Affect the Rate of Gating Charge Recovery in Wild-type and W434F Shaker Channels through a Variety of Mechanisms
J. Gen. Physiol., April 29, 2002; 119(5): 467 - 486.
[Abstract] [Full Text] [PDF]



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