| id |
pubmed-2229332
|
| recordtype |
oai_dc
|
| spelling |
pubmed-22293322008-04-23 Nonequilibrium gating and voltage dependence of the ClC-0 Cl- channel Articles The gating of ClC-0, the voltage-dependent Cl- channel from Torpedo electric organ, is strongly influenced by Cl- ions in the external solution. Raising external Cl- over the range 1-600 mM favors the fast- gating open state and disfavors the slow-gating inactivated state. Analysis of purified single ClC-0 channels reconstituted into planar lipid bilayers was used to identify the role of Cl- ions in the channel's fast voltage-dependent gating process. External, but not internal, Cl- had a major effect on the channel's opening rate constant. The closing rate was more sensitive to internal Cl- than to external Cl-. Both opening and closing rates varied with voltage. A model was derived that postulates (a) that in the channel's closed state, Cl- is accessible to a site located at the outer end of the conduction pore, where it binds in a voltage-independent fashion, (b) that this closed conformation can open, whether liganded by Cl- or not, in a weakly voltage-dependent fashion, (c) that the Cl(-)-liganded closed channel undergoes a conformational change to a different closed state, such that concomitant with this change, Cl- ion moves inward, conferring voltage-dependence to this step, and (d) that this new Cl(-)- liganded closed state opens with a very high rate. According to this picture, Cl- movement within the pre-open channel is the major source of voltage dependence, and charge movement intrinsic to the channel protein contributes very little to voltage-dependent gating of ClC-0. Moreover, since the Cl- activation site is probably located in the ion conduction pathway, the fast gating of ClC-0 is necessarily coupled to ion conduction, a nonequilibrium process. The Rockefeller University Press 1996-10-01 /pmc/articles/PMC2229332/ /pubmed/8894974 Text en This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.rupress.org/terms). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 4.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/4.0/).
|
| repository_type |
Open Access Journal
|
| institution_category |
Foreign Institution
|
| institution |
US National Center for Biotechnology Information
|
| building |
NCBI PubMed
|
| collection |
Online Access
|
| language |
English
|
| format |
Online
|
| title |
Nonequilibrium gating and voltage dependence of the ClC-0 Cl- channel
|
| spellingShingle |
Nonequilibrium gating and voltage dependence of the ClC-0 Cl- channel
|
| title_short |
Nonequilibrium gating and voltage dependence of the ClC-0 Cl- channel
|
| title_full |
Nonequilibrium gating and voltage dependence of the ClC-0 Cl- channel
|
| title_fullStr |
Nonequilibrium gating and voltage dependence of the ClC-0 Cl- channel
|
| title_full_unstemmed |
Nonequilibrium gating and voltage dependence of the ClC-0 Cl- channel
|
| title_sort |
nonequilibrium gating and voltage dependence of the clc-0 cl- channel
|
| description |
The gating of ClC-0, the voltage-dependent Cl- channel from Torpedo electric organ, is strongly influenced by Cl- ions in the external solution. Raising external Cl- over the range 1-600 mM favors the fast- gating open state and disfavors the slow-gating inactivated state. Analysis of purified single ClC-0 channels reconstituted into planar lipid bilayers was used to identify the role of Cl- ions in the channel's fast voltage-dependent gating process. External, but not internal, Cl- had a major effect on the channel's opening rate constant. The closing rate was more sensitive to internal Cl- than to external Cl-. Both opening and closing rates varied with voltage. A model was derived that postulates (a) that in the channel's closed state, Cl- is accessible to a site located at the outer end of the conduction pore, where it binds in a voltage-independent fashion, (b) that this closed conformation can open, whether liganded by Cl- or not, in a weakly voltage-dependent fashion, (c) that the Cl(-)-liganded closed channel undergoes a conformational change to a different closed state, such that concomitant with this change, Cl- ion moves inward, conferring voltage-dependence to this step, and (d) that this new Cl(-)- liganded closed state opens with a very high rate. According to this picture, Cl- movement within the pre-open channel is the major source of voltage dependence, and charge movement intrinsic to the channel protein contributes very little to voltage-dependent gating of ClC-0. Moreover, since the Cl- activation site is probably located in the ion conduction pathway, the fast gating of ClC-0 is necessarily coupled to ion conduction, a nonequilibrium process.
|
| publisher |
The Rockefeller University Press
|
| publishDate |
1996
|
| url |
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2229332/
|
| _version_ |
1611437813480292352
|