Conductance and permeability of the residual state of connexin43 gap junction channels.
Conductance and permeability of the residual state of connexin43 gap junction channels.
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DOI：
10.1085/jgp.119.2.171
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发表时间：
2002-02
期刊：
影响因子：
--
通讯作者：
Verselis VK
中科院分区：
文献类型：
--
作者：
Bukauskas FF;Bukauskiene A;Verselis VK
我们使用表达野生型连接蛋白43和连接蛋白43的细胞系与增强型绿色荧光蛋白(Cx43-EGFP)融合来检测Cx43同型和Cx43/Cx43-EGFP异型缝隙连接通道残余态的电导和膜选择性。Cx43单元-单元通道中的每个半通道具有两个门：一个用于将通道关闭到残余态的快门和一个用于完全关闭通道的慢门；交叉点电压(Vj)关闭处于相对负侧的半通道中的快门。在这里，我们在宏观和单通道水平上证明了剩余态的I-V关系被纠正，在门控半通道一侧负的较高的VJ处表现出更高的电导。当用Asp−取代Cl−时，整流度增加，而用TEA+取代K+时，整流度减小。这些数据与残余态的阴离子选择性增加是一致的。VJ门控通道不能渗透单价正负电荷染料，而单价正负电荷染料很容易通过完全开放的通道渗透。这些数据表明，沟道孔的收窄伴随着向残余态的选通。我们认为，快门通过构象变化来运作，在门控半通道的细胞质前庭引入正电荷，从而产生电流整流，增加阴离子选择性，并使通道孔变窄，这在很大程度上是降低通道电导和限制染料转移的原因。因此，快速的VJ敏感门控机制可以作为选择性过滤器，允许电耦合，但限制新陈代谢交流。
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.
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DOI：
10.1085/jgp.114.3.339
发表时间：
1999-09
期刊：
The Journal of general physiology
影响因子：
--
作者：
Oh S;Rubin JB;Bennett MV;Verselis VK;Bargiello TA
通讯作者：
Bargiello TA
影响因子：
7.8
作者：
PERACCHIA, C
通讯作者：
PERACCHIA, C
DOI：
10.1083/jcb.129.3.805
发表时间：
1995-05
期刊：
The Journal of cell biology
影响因子：
--
作者：
Elfgang C;Eckert R;Lichtenberg-Fraté H;Butterweck A;Traub O;Klein RA;Hülser DF;Willecke K
通讯作者：
Willecke K
影响因子：
3.4
作者：
BUKAUSKAS, FF;WEINGART, R
通讯作者：
WEINGART, R
影响因子：
3.4
作者：
Revilla, A;Castro, C;Barrio, LC
通讯作者：
Barrio, LC