EFFECT OF PHOSPHOLIPID SURFACE-CHARGE ON THE CONDUCTANCE AND GATING OF A CA-2+-ACTIVATED K+ CHANNEL IN PLANAR LIPID BILAYERS
EFFECT OF PHOSPHOLIPID SURFACE-CHARGE ON THE CONDUCTANCE AND GATING OF A CA-2+-ACTIVATED K+ CHANNEL IN PLANAR LIPID BILAYERS
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DOI：
10.1007/bf01868701
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发表时间：
1985-01-01
影响因子：
2.4
通讯作者：
LATORRE, R
中科院分区：
文献类型：
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作者：
MOCZYDLOWSKI, E;ALVAREZ, O;LATORRE, R
在磷脂酰乙醇胺（PE）或磷脂酰丝氨酸（PS）形成的人工脂质双层中，研究了大鼠骨骼肌质膜上钙激活的钾选择性通道。在PE中，单通道电导表现出复杂的依赖于对称的K+浓度，不能描述简单的米氏饱和。在低K+浓度的通道电导率较高的PS膜，但接近相同的电导率观察到PE以上0.4 M KCl。在相同的Ca ~（2+）浓度和电压下，PS的通道开放概率显著高于PE。在2种脂质中观察到的传导和门控的差异可以通过与中性PE膜相比PS的负表面电荷来解释。使用Gouy-Chapman-Stern理论，在离PS膜表面不同距离处K+和Ca 2+的预期浓度的模型计算表明，K+-传导和Ca 2 +-活化位点感测表面电势的类似部分，相当于在9埃距离处的局部静电电势。从表面上看。
A Ca activated, K selective channel from plasma membrane of rat skeletal muscle was studied in artificial lipid bilayers formed from either phosphatidylethanolamine (PE) or phosphatidylserine (PS). In PE, the single-channel conductance exhibited a complex dependence on symmetrical K+ concentration that could not be described by simple Michaelis-Menten saturation. At low K+ concentrations the channel conductance was higher in PS membranes, but approached the same conductance observed in PE above 0.4 M KCl. At the same Ca2+ concentration and voltage, the probability of channel opening was significantly greater in PS than PE. The differences in the conduction and gating, observed in the 2 lipids, can be explained by the negative surface charge of PS compared to the neutral PE membrane. Model calculations of the expected concentrations of K+ and Ca2+ at various distances from a PS membrane surface, using Gouy-Chapman-Stern theory, suggest that the K+-conduction and Ca2+-activation sites sense a similar fraction of the surface potential, equivalent to the local electrostatic potential at a distance of 9 .ANG. from the surface.