Ildefonse M, Bennett N
Unité de Recherche Associée 520 du Centre National de la Recherche Scientifique, Centre d'Etudes Nucléaires de Grenoble, France.
J Membr Biol. 1991 Aug;123(2):133-47. doi: 10.1007/BF01998084.
Unitary currents through cGMP-dependent channels of retinal rods are observed following incorporation into planar lipid bilayers of native vesicles from purified rod outer segment membranes washed free of soluble and peripheral proteins. The influence of the concentration of cGMP, inhibitors (cis-diltiazem, tetracaine and Ag+) and divalent cations (Ca2+, Mg2+, and Co2+) on the conductance and open probability of the channel is described, as well as the voltage dependence of these effects. The cGMP dependence suggests the existence of four binding sites for cGMP and reveals that sequential binding of four cGMP molecules corresponds to the opening of four discrete conductance levels. Finally, we provide conclusive evidence that activated G-protein does not directly inactivate the cGMP-dependent channels of bovine retinal rods.
在将从纯化的视杆外段膜中洗去可溶性和外周蛋白的天然囊泡整合到平面脂质双分子层后，观察到通过视杆细胞中环鸟苷酸（cGMP）依赖性通道的单一电流。描述了cGMP浓度、抑制剂（顺式地尔硫卓、丁卡因和Ag +）和二价阳离子（Ca2 +、Mg2 +和Co2 +）对通道电导和开放概率的影响，以及这些效应的电压依赖性。cGMP依赖性表明存在四个cGMP结合位点，并揭示四个cGMP分子的顺序结合对应于四个离散电导水平的开放。最后，我们提供了确凿的证据，即活化的G蛋白不会直接使牛视网膜视杆细胞的cGMP依赖性通道失活。
