REPULSION BETWEEN TETRAETHYLAMMONIUM IONS IN CLONED VOLTAGE-GATED POTASSIUM CHANNELS
REPULSION BETWEEN TETRAETHYLAMMONIUM IONS IN CLONED VOLTAGE-GATED POTASSIUM CHANNELS
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DOI：
10.1016/0896-6273(92)90212-v
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发表时间：
1992-05-01
期刊：
影响因子：
16.2
通讯作者：
ALMERS, W
中科院分区：
文献类型：
--
作者：
NEWLAND, CF;ADELMAN, JP;ALMERS, W
四乙基铵离子（TEA+）通过作用于位于水孔相对两端的两个位点来阻断电压门控K+通道。这使我们能够测试离子渗透模型做出的两个预测，即K+通道可以同时被多个离子占据，并且离子相互排斥。我们表明，外部应用TEA+拮抗块内部TEA+，反之亦然。拮抗作用小于竞争性结合的预期，因此TEA+可能同时占据两个位点。外部TEA+和内部TEA+使彼此的亲和力降低4至5倍。此外，K+拮抗TEA+在膜的对侧的阻断，并且外部TEA+拮抗被内部Ba 2+阻断。在膜的相对侧施加的离子之间的拮抗作用可能是所有与K+通道结合的阳离子所共有的。
Tetraethylammonium ion (TEA+) blocks voltage-gated K+ channels by acting at two sites located at opposite ends of the aqueous pore. This allowed us to test two predictions made by models of ion permeation, namely that K+ channels can be simultaneously occupied by multiple ions and that the ions repel each other. We show that externally applied TEA+ antagonize block by internal TEA+ and vice versa. The antagonism is less than predicted for competitive binding, hence TEA+ may occupy both sites simultaneously. External TEA+ and internal TEA+ reduce each others affinity 4- to 5-fold. In addition, K+ antagonizes block by TEA+ at the opposite side of the membrane, and external TEA+ antagonizes is block by internal Ba2+. The antagonism between ions applied at opposite sides of the membrane may be common to all cations binding to K+ channels.