CGMP-DEPENDENT CHANNEL PROTEIN FROM PHOTORECEPTOR-MEMBRANES - SINGLE-CHANNEL ACTIVITY OF THE PURIFIED AND RECONSTITUTED PROTEIN
CGMP-DEPENDENT CHANNEL PROTEIN FROM PHOTORECEPTOR-MEMBRANES - SINGLE-CHANNEL ACTIVITY OF THE PURIFIED AND RECONSTITUTED PROTEIN
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DOI：
10.1073/pnas.85.1.94
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发表时间：
1988-01-01
影响因子：
11.1
通讯作者：
KAUPP, UB
中科院分区：
文献类型：
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作者：
HANKE, W;COOK, NJ;KAUPP, UB
cgmp依赖性通道蛋白已从牛棒光感受器膜中纯化并整合到平面脂质膜中。在低二价阳离子浓度下，cGMP刺激单通道电流波动。通道打开的概率Po与cGMP浓度密切相关（EC50 = 31 μ m； Hill系数，n = 2.3）；而单通道电导(。= 26 pS)与激动剂浓度无关。激动剂刺激的开放通道概率的增加主要是由于关闭时间缩短，在较小程度上是由于通道保持开放的时间更长。单个打开通道的电流-电压关系偏离欧姆行为，并且在负膜电位较大时打开概率降低。孔道门控的电压依赖性和开放孔道的电流-电压曲线的非线性可以解释包含多个孔道副本的人工双层中宏观cgmp感应电流的整流。电流波动表现出各种亚电平，表明该通道可能存在于一种以上的导电状态。
The cGMP-dependent channel protein has been purified from bovine rod photoreceptor membranes and incorporated into planar lipid membranes. At low divalent cation concentrations, cGMP stimulated single-channel current fluctuations. The probability Po of the channel being open strongly depended on the cGMP concentration (EC50 = 31 .mu.M; Hill coefficient, n = 2.3); whereas the single-channel conductance (.LAMBDA. = 26 pS) was independent of the agonist concentration. The agonist-stimulated increase in the probability of an open channel was largely due to shorter closed times and, to a lesser extent, due to the channel staying open for a longer time. The current-voltage relationship of the single open channel deviated from ohmic behavior, and the open probability decreased at more negative membrane potentials. The rectification of the macroscopic cGMP-induced current in artificial bilayers that contained many channel copies can be accounted for by the voltage dependence of channel gating together with the nonlinearity of the current-voltage curve of an open channel. Current fluctuations exhibited a variety of sublevels, indicating that the channel may exist in more than one conductive state.