Tetracaine reports a conformational change in the pore of cyclic nucleotide-gated channels.
Tetracaine reports a conformational change in the pore of cyclic nucleotide-gated channels.
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四卡因报告循环核苷酸门控通道孔的构象变化。
DOI：
10.1085/jgp.110.5.591
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发表时间：
1997-11
影响因子：
3.8
通讯作者：
Zagotta, WN
中科院分区：
文献类型：
--
作者：
Fodor, AA;Black, KD;Zagotta, WN
局麻药是一类临床上有用的化合物，可作为电压和环核苷酸门控(CNG)离子通道的孔道阻滞剂。我们使用局部麻醉剂丁卡因来探索CNG通道在开放变构转变过程中的构象变化的本质。当应用于非洲爪哇卵母细胞表达的α亚基野生型杆状CNG通道的胞内侧时，局麻药丁卡因表现出状态依赖的阻断，与闭合状态的结合比与开放状态的亲和力高得多。在这里，我们证明了保守的P区(E363G)上的一个谷氨酸的中和消除了丁卡因阻断的这种状态依赖性。丁卡因阻断E363G通道的效果在高浓度cGMP通道开放时间较长时和低浓度cGMP通道关闭时间较长时具有相同的效果。此外，促进开放变构转换的Ni2+降低了丁卡因阻断野生型通道的效果，但不影响E363G通道的作用。在嵌合的CNG通道中也得到了类似的结果，该通道表现出更有利的开放变构转变。这些结果表明，在封闭的孔道构型中，E363可以被内部丁卡因访问，但在开放的孔道中不能被访问，并且伴随着孔道打开的构象变化包括E363的构象或可访问性的变化。
Local anesthetics are a diverse group of clinically useful compounds that act as pore blockers of both voltage- and cyclic nucleotide–gated (CNG) ion channels. We used the local anesthetic tetracaine to probe the nature of the conformational change that occurs in the pore of CNG channels during the opening allosteric transition. When applied to the intracellular side of wild-type rod CNG channels expressed in Xenopus oocytes from the α subunit, the local anesthetic tetracaine exhibits state-dependent block, binding with much higher affinity to closed states than to open states. Here we show that neutralization of a glutamic acid in the conserved P region (E363G) eliminated this state dependence of tetracaine block. Tetracaine blocked E363G channels with the same effectiveness at high concentrations of cGMP, when the channel spent more time open, and at low concentrations of cGMP, when the channel spent more time closed. In addition, Ni2+, which promotes the opening allosteric transition, decreased the effectiveness of tetracaine block of wild-type but not E363G channels. Similar results were obtained in a chimeric CNG channel that exhibits a more favorable opening allosteric transition. These results suggest that E363 is accessible to internal tetracaine in the closed but not the open configuration of the pore and that the conformational change that accompanies channel opening includes a change in the conformation or accessibility of E363.
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DOI：
10.1085/jgp.109.1.3
发表时间：
1997-01
期刊：
The Journal of general physiology
影响因子：
--
作者：
Fodor AA;Gordon SE;Zagotta WN
通讯作者：
Zagotta WN
影响因子：
3.4
作者：
Sesti, F;Nizzari, M;Torre, V
通讯作者：
Torre, V
影响因子：
3.8
作者：
KARPEN, JW;BROWN, RL;BAYLOR, DA
通讯作者：
BAYLOR, DA
影响因子：
5.5
作者：
Bucossi, G;Eismann, E;Torre, V
通讯作者：
Torre, V
影响因子：
16.2
作者：
Sun, ZP;Akabas, MH;Siegelbaum, SA
通讯作者：
Siegelbaum, SA