Conductance and Permeability of the Residual State of Connexin43 Gap Junction Channels

We used cell lines expressing wild-type connexin43 and connexin43 fused with the enhanced green fluorescent protein (Cx43-EGFP) to examine conductance and perm-selectivity of the residual state of Cx43 homotypic and Cx43/Cx43-EGFP heterotypic gap junction channels. Each hemichannel in Cx43 cell–cell...

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Main Authors:	Bukauskas, Feliksas F., Bukauskiene, Angele, Verselis, Vytas K.
Format:	Online
Language:	English
Published:	The Rockefeller University Press 2002
Online Access:	https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2233803/

id	pubmed-2233803
recordtype	oai_dc
spelling	pubmed-22338032008-04-21 Conductance and Permeability of the Residual State of Connexin43 Gap Junction Channels Bukauskas, Feliksas F. Bukauskiene, Angele Verselis, Vytas K. Original Article We used cell lines expressing wild-type connexin43 and connexin43 fused with the enhanced green fluorescent protein (Cx43-EGFP) to examine conductance and perm-selectivity of the residual state of Cx43 homotypic and Cx43/Cx43-EGFP heterotypic gap junction channels. Each hemichannel in Cx43 cell–cell channel possesses two gates: a fast gate that closes channels to the residual state and a slow gate that fully closes channels; the transjunctional voltage (Vj) closes the fast gate in the hemichannel that is on the relatively negative side. Here, we demonstrate macroscopically and at the single-channel level that the I-V relationship of the residual state rectifies, exhibiting higher conductance at higher Vjs that are negative on the side of gated hemichannel. The degree of rectification increases when Cl− is replaced by Asp− and decreases when K+ is replaced by TEA+. These data are consistent with an increased anionic selectivity of the residual state. The Vj-gated channel is not permeable to monovalent positively and negatively charged dyes, which are readily permeable through the fully open channel. These data indicate that a narrowing of the channel pore accompanies gating to the residual state. We suggest that the fast gate operates through a conformational change that introduces positive charge at the cytoplasmic vestibule of the gated hemichannel, thereby producing current rectification, increased anionic selectivity, and a narrowing of channel pore that is largely responsible for reducing channel conductance and restricting dye transfer. Consequently, the fast Vj-sensitive gating mechanism can serve as a selectivity filter, which allows electrical coupling but limits metabolic communication. The Rockefeller University Press 2002-02 /pmc/articles/PMC2233803/ /pubmed/11815667 Text en Copyright © 2002, The Rockefeller University Press 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
author	Bukauskas, Feliksas F. Bukauskiene, Angele Verselis, Vytas K.
spellingShingle	Bukauskas, Feliksas F. Bukauskiene, Angele Verselis, Vytas K. Conductance and Permeability of the Residual State of Connexin43 Gap Junction Channels
author_facet	Bukauskas, Feliksas F. Bukauskiene, Angele Verselis, Vytas K.
author_sort	Bukauskas, Feliksas F.
title	Conductance and Permeability of the Residual State of Connexin43 Gap Junction Channels
title_short	Conductance and Permeability of the Residual State of Connexin43 Gap Junction Channels
title_full	Conductance and Permeability of the Residual State of Connexin43 Gap Junction Channels
title_fullStr	Conductance and Permeability of the Residual State of Connexin43 Gap Junction Channels
title_full_unstemmed	Conductance and Permeability of the Residual State of Connexin43 Gap Junction Channels
title_sort	conductance and permeability of the residual state of connexin43 gap junction channels
description	We used cell lines expressing wild-type connexin43 and connexin43 fused with the enhanced green fluorescent protein (Cx43-EGFP) to examine conductance and perm-selectivity of the residual state of Cx43 homotypic and Cx43/Cx43-EGFP heterotypic gap junction channels. Each hemichannel in Cx43 cell–cell channel possesses two gates: a fast gate that closes channels to the residual state and a slow gate that fully closes channels; the transjunctional voltage (Vj) closes the fast gate in the hemichannel that is on the relatively negative side. Here, we demonstrate macroscopically and at the single-channel level that the I-V relationship of the residual state rectifies, exhibiting higher conductance at higher Vjs that are negative on the side of gated hemichannel. The degree of rectification increases when Cl− is replaced by Asp− and decreases when K+ is replaced by TEA+. These data are consistent with an increased anionic selectivity of the residual state. The Vj-gated channel is not permeable to monovalent positively and negatively charged dyes, which are readily permeable through the fully open channel. These data indicate that a narrowing of the channel pore accompanies gating to the residual state. We suggest that the fast gate operates through a conformational change that introduces positive charge at the cytoplasmic vestibule of the gated hemichannel, thereby producing current rectification, increased anionic selectivity, and a narrowing of channel pore that is largely responsible for reducing channel conductance and restricting dye transfer. Consequently, the fast Vj-sensitive gating mechanism can serve as a selectivity filter, which allows electrical coupling but limits metabolic communication.
publisher	The Rockefeller University Press
publishDate	2002
url	https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2233803/
_version_	1611438328788287488

Conductance and Permeability of the Residual State of Connexin43 Gap Junction Channels

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