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首页> 外文期刊>American Journal of Physiology >Is the chemical gate of connexins voltage sensitive? Behavior of Cx32 wild-type and mutant channels.
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Is the chemical gate of connexins voltage sensitive? Behavior of Cx32 wild-type and mutant channels.

机译：连接蛋白的化学门电压敏感吗？ Cx32野生型和突变通道的行为。

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摘要

Connexin channels are gated by transjunctional voltage (Vj) or CO2 via distinct mechanisms. The cytoplasmic loop (CL) and arginines of a COOH-terminal domain (CT1) of connexin32 (Cx32) were shown to determine CO2 sensitivity, and a gating mechanism involving CL-CT1 association-dissociation was proposed. This study reports that Cx32 mutants, tandem, 5R/E, and 5R/N, designed to weaken CL-CT1 interactions, display atypical Vj and CO2 sensitivities when tested heterotypically with Cx32 wild-type channels in Xenopus oocytes. In tandems, two Cx32 monomers are linked NH2-to-COOH terminus. In 5R/E and 5R/N mutants, glutamates or asparagines replace CT1 arginines. On the basis of the intriguing sensitivity of the mutant-32 channel to Vj polarity, the existence of a "slow gate" distinct from the conventional Vj gate is proposed. To a lesser extent the slow gate manifests itself also in homotypic Cx32 channels. Mutant-32 channels are more CO2 sensitive than homotypic Cx32 channels, and CO2-induced chemical gating is reversed with relative depolarization of the mutant oocyte, suggesting Vj sensitivity of chemical gating. A hypothetical pore-plugging model involving an acidic cytosolic protein (possibly calmodulin) is discussed.
机译：连接蛋白通道通过独特的机制受到跨结电压（Vj）或CO2的控制。连接蛋白32（Cx32）的COOH末端域（CT1）的胞质环（CL）和精氨酸显示确定CO2敏感性，并提出了涉及CL-CT1缔合解离的门控机制。这项研究报告说，当用非洲爪蟾卵母细胞中的Cx32野生型通道异型测试时，旨在减弱CL-CT1相互作用的Cx32突变体串联，5R / E和5R / N表现出非典型的Vj和CO2敏感性。在双环中，两个Cx32单体连接到NH2-COOH末端。在5R / E和5R / N突变体中，谷氨酸或天冬酰胺取代CT1精氨酸。基于突变32通道对Vj极性的吸引人的敏感性，提出了不同于常规Vj门的“慢门”的存在。在较小的程度上，慢速门也出现在同型Cx32通道中。突变32通道比同型Cx32通道更对CO2敏感，并且CO2诱导的化学门控与突变卵母细胞的相对去极化相反，表明化学门控的Vj敏感性。讨论了涉及酸性胞质蛋白（可能是钙调蛋白）的假设的孔堵塞模型。

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