Molecular dissection of transjunctional voltage dependence in the connexin-32 and connexin-43 junctions
Molecular dissection of transjunctional voltage dependence in the connexin-32 and connexin-43 junctions
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DOI：
10.1016/s0006-3495(99)76986-9
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发表时间：
1999-09-01
影响因子：
3.4
通讯作者：
Barrio, LC
中科院分区：
文献类型：
--
作者：
Revilla, A;Castro, C;Barrio, LC
大多数缝隙连接通道对两个细胞内部之间的电压差很敏感，称为跨结电压(V-j)。在几个结中，由V-j引起的电导跃迁表现出不止一个动力学分量。为了阐明连接蛋白-32(Cx32)和连接蛋白-43(Cx43)连接的快慢成分的结构基础，我们对这两个连接蛋白进行了缺失，其中大部分羧基末端(CT)结构域被移除。野生型和“无尾”突变体在非洲爪哇卵母细胞中表达，并用双电压钳技术分析宏观门控特性。Cx32和Cx43的CT结构域的截断消除了电导转变的快速机制，并产生了新的门控特性，这在很大程度上归因于门控的慢速机制。由野生型和截短型半通道组成的杂交连接的形成使我们可以推断，门的快慢成分存在于每个半通道中，并且两个门在细胞质一侧以负的V-j关闭。因此，我们得出结论，V-j敏感电导的两个动力学分量是两种不同的门控机制作用的结果。它们在Cx32和Cx43分子中构成不同的结构，CT结构域是快速V-j门控的组成部分。
Most gap junction channels are sensitive to the voltage difference between the two cellular interiors, termed the transjunctional voltage (V-j). In several junctions, the conductance transitions induced by V-j show more than one kinetic component. To elucidate the structural basis of the fast and slow components that characterize the V-j dependence of connexin-32 (Cx32) and connexin-43 (Cx43) junctions, we created deletions of both connexins, where most of the carboxyterminal (CT) domain was removed. The wild-type and "tailless" mutants were expressed in paired Xenopus oocytes, and the macroscopic gating properties were analyzed using the dual voltage clamp technique. Truncation of the CT domain of Cx32 and Cx43 abolished the fast mechanism of conductance transitions and induced novel gating properties largely attributable to the slow mechanism of gating. The formation of hybrid junctions comprising wild-type and truncated hemichannels allowed us to infer that the fast and slow components of gating reside in each hemichannel and that both gates close at a negative V-j on the cytoplasmic side. Thus we conclude that the two kinetic components of V-j-sensitive conductance are a result of the action of two different gating mechanisms. They constitute separate structures in the Cx32 and Cx43 molecules, the CT domain being an integral part of fast V-j gating.