The Journal of General Physiology
Scientifica: Experts in Electrophysiology
  Home | Help | Feedback | Subscriptions | Archive | Search | Table of Contents
Published 29 September 2003. doi:10.1085/jgp.200308818
This Article
Right arrow Full Text
Right arrow Full Text (PDF, 634K)
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 Latorre, R.
Right arrow Articles by Alvarez, O.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Latorre, R.
Right arrow Articles by Alvarez, O.
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?
© Rockefeller University Press, 0022-1295/2003/10/459/ $5.00
Journal of General Physiology, Volume 122, Number 4, October 2003 459-469

Molecular Coupling between Voltage Sensor and Pore Opening in the Arabidopsis Inward Rectifier K+ Channel KAT1

Ramon Latorre1,2, Riccardo Olcese3, Claudia Basso4, Carlos Gonzalez1,2, Fabian Muñoz1, Diego Cosmelli1 and Osvaldo Alvarez1,2

1 Laboratory of Biophysics and Molecular Physiology, Centro de Estudios Científicos, Valdivia, Chile
2 Department of Biology Faculty of Sciences, University of Chile Santiago, Chile
3 Department of Anesthesiology, Division of Molecular Medicine, and Brain Research Institute, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA 90095
4 Biomedical Sciences Institute Faculty of Medicine, University of Chile, Casilla 70058, Santiago-7, Chile

Address correspondence to Dr. Ramon Latorre Laboratory of Biophysics and Molecular Physiology Centro de Estudios Científicos Arturo Prat 514 Valdivia, Chile. Fax: (56) 63-234515; email: ramon{at}cecs.cl

Animal and plant voltage-gated ion channels share a common architecture. They are made up of four subunits and the positive charges on helical S4 segments of the protein in animal K+ channels are the main voltage-sensing elements. The KAT1 channel cloned from Arabidopsis thaliana, despite its structural similarity to animal outward rectifier K+ channels is, however, an inward rectifier. Here we detected KAT1-gating currents due to the existence of an intrinsic voltage sensor in this channel. The measured gating currents evoked in response to hyperpolarizing voltage steps consist of a very fast ({tau} = 318 ± 34 µs at -180 mV) and a slower component (4.5 ± 0.5 ms at -180 mV) representing charge moved when most channels are closed. The observed gating currents precede in time the ionic currents and they are measurable at voltages (less than or equal to -60) at which the channel open probability is negligible ({approx}10-4). These two observations, together with the fact that there is a delay in the onset of the ionic currents, indicate that gating charge transits between several closed states before the KAT1 channel opens. To gain insight into the molecular mechanisms that give rise to the gating currents and lead to channel opening, we probed external accessibility of S4 domain residues to methanethiosulfonate-ethyltrimethylammonium (MTSET) in both closed and open cysteine-substituted KAT1 channels. The results demonstrate that the putative voltage–sensing charges of S4 move inward when the KAT1 channels open.

Key Words: KAT1 channels • inward rectifier • gating currents • cysteine accessibility • voltage sensor


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?


This article has been cited by other articles:


Home page
 Mol PlantHome page
J. Riedelsberger, T. Sharma, W. Gonzalez, P. Gajdanowicz, S. E. Morales-Navarro, C. Garcia-Mata, B. Mueller-Roeber, F. D. Gonzalez-Nilo, M. R. Blatt, and I. Dreyer
Distributed Structures Underlie Gating Differences between the Kin Channel KAT1 and the Kout Channel SKOR
Mol Plant, January 1, 2010; 3(1): 236 - 245.
[Abstract] [Full Text] [PDF]

Home page
 JGPHome page
J. S. Santos, A. Lundby, C. Zazueta, and M. Montal
Molecular Template for a Voltage Sensor in a Novel K+ Channel. I. Identification and Functional Characterization of KvLm, a Voltage-gated K+ Channel from Listeria monocytogenes
J. Gen. Physiol., August 28, 2006; 128(3): 283 - 292.
[Abstract] [Full Text] [PDF]

Home page
 JGPHome page
A. Lundby, J. S. Santos, C. Zazueta, and M. Montal
Molecular Template for a Voltage Sensor in a Novel K+ Channel. II. Conservation of a Eukaryotic Sensor Fold in a Prokaryotic K+ Channel
J. Gen. Physiol., August 28, 2006; 128(3): 293 - 300.
[Abstract] [Full Text] [PDF]

Home page
 JGPHome page
E. Michard, B. Lacombe, F. Poree, B. Mueller-Roeber, H. Sentenac, J.-B. Thibaud, and I. Dreyer
A Unique Voltage Sensor Sensitizes the Potassium Channel AKT2 to Phosphoregulation
J. Gen. Physiol., November 28, 2005; 126(6): 605 - 617.
[Abstract] [Full Text] [PDF]

Home page
 JGPHome page
D. C. Bell, H. Yao, R. C. Saenger, J. H. Riley, and S. A. Siegelbaum
Changes in Local S4 Environment Provide a Voltage-sensing Mechanism for Mammalian Hyperpolarization-activated HCN Channels
J. Gen. Physiol., December 29, 2003; 123(1): 5 - 20.
[Abstract] [Full Text] [PDF]

Home page
 JGPHome page
R. Horn
How S4 Segments Move Charge. Let Me Count the Ways
J. Gen. Physiol., December 29, 2003; 123(1): 1 - 4.
[Full Text] [PDF]


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