The carboxyl terminal residues 220-283 are not required for voltage gating of a chimeric connexin32 hemichannel.
The carboxyl terminal residues 220-283 are not required for voltage gating of a chimeric connexin32 hemichannel.
复制标题
嵌合 connexin32 半通道的电压门控不需要羧基末端残基 220-283。
DOI：
10.1016/j.bpj.2013.08.015
复制
发表时间：
2013
影响因子：
3.4
通讯作者：
Bargiello,ThaddeusA
中科院分区：
文献类型：
--
作者：
Kwon,Taekyung;Dowd,TerryL;Bargiello,ThaddeusA
连接蛋白半通道显示两种不同形式的电压依赖性门控，对应于Vj-或快速门控和环-或慢速门控的操作。据报道，连接蛋白32的羧基末端（CT）是Vj（快速）门操作所需的，但这一结论是从跨接电压引起的CT截短细胞间通道宏观电流中快速动力学成分的损失推断出来的。这样的推论是复杂的存在下，快速和缓慢的门在每个半通道和串行头对头排列这些门在细胞间通道。在未对接的半通道中检查电压门控和通过氨基末端结构域中的负电荷取代（N2 E）的Vjgate极性反转允许明确分离Cx 32嵌合体（Cx 32 Δ 43 E1）中的两个门控过程。这种嵌合体在异种卵母细胞中表达了非对接的半通道电流，并为研究Cx 32电压门控的分子决定因素和机制提供了模型系统。在这里，我们表明，bothVj-和循环门是可操作的截断突变，删除所有，但前四个CT残基（ACAR 219）的Cx 32 Δ 43 E1半通道。我们得出结论，操作Cx 32 Vj（快）门不需要CT残基220-283，如先前由其他人报道的。
Connexin hemichannels display two distinct forms of voltage-dependent gating, corresponding to the operation ofVj- or fast gates and loop- or slow gates. The carboxyl terminus (CT) of connexin 32 has been reported to be required for the operation of theVj(fast) gates, but this conclusion was inferred from the loss of a fast kinetic component in macroscopic currents of CT-truncated intercellular channels elicited by transjunctional voltage. Such inferences are complicated by presence of both fast and slow gates in each hemichannel and the serial head-to-head arrangement of these gates in the intercellular channel. Examination of voltage gating in undocked hemichannels andVjgate polarity reversal by a negative charge substitution (N2E) in the amino terminal domain allow unequivocal separation of the two gating processes in a Cx32 chimera (Cx32∗43E1). This chimera expresses currents as an undocked hemichannel inXenopusoocytes and provides a model system to study the molecular determinants and mechanisms of Cx32 voltage gating. Here, we demonstrate that bothVj- and loop gates are operational in a truncation mutation that removes all but the first four CT residues (ACAR219) of the Cx32∗43E1 hemichannel. We conclude that an operational Cx32Vj(fast) gate does not require CT residues 220–283, as reported previously by others.