Functional reconstitution of the purified brain sodium channel in planar lipid bilayers.
Functional reconstitution of the purified brain sodium channel in planar lipid bilayers.
复制标题
平面脂质双层中纯化脑钠通道的功能重建。
DOI：
10.1073/pnas.82.1.240
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发表时间：
1985
影响因子：
11.1
通讯作者：
Montal,M
中科院分区：
文献类型：
--
作者：
Hartshorne,RP;Keller,BU;Talvenheimo,JA;Catterall,WA;Montal,M
在平面脂双层膜中研究了蛙毒素对大鼠脑钠通道的离子传导和电压依赖性。单通道电流清晰可见。通道开放是电压依赖性的，并且受去极化的影响。通道在50%的时间内打开时的电压为-91 +/-17 mV（SD，n = 22），表观门控电荷约为4。河豚毒素可逆地阻断通过钠通道的离子电流。河豚毒素阻断的Ki在-50 mV时为8.3 nM，并且对于43 mV的去极化，Ki增加e倍，具有电压依赖性。单沟道电导γ是欧姆的。在0.5 M盐浓度下，Na+ γ = 25 pS，K+ γ = 3.5 pS，Rb+ γ = 1.2 pS。这项研究表明，纯化的脑钠通道-由三个多肽亚基组成：α（Mr约为260，000），β 1（Mr约为39，000）和β 2（Mr约为37，000）-表现出与天然钠通道相同的电压依赖性，神经毒素敏感性和离子选择性。
The ion conduction and voltage dependence of sodium channels purified from rat brain were investigated in planar lipid bilayers in the presence of batrachotoxin. Single channel currents are clearly resolved. Channel opening is voltage dependent and favored by depolarization. The voltage at which the channel is open 50% of the time is -91 +/- 17 mV (SD, n = 22) and the apparent gating charge is approximately 4. Tetrodotoxin reversibly blocks the ionic current through the sodium channels. The Ki for the tetrodotoxin block is 8.3 nM at -50 mV and is voltage dependent with the Ki increasing e-fold for depolarizations of 43 mV. The single channel conductance, gamma, is ohmic. At 0.5 M salt concentrations gamma = 25 pS for Na+, 3.5 pS for K+, and 1.2 pS for Rb+. This study demonstrates that the purified brain sodium channel--which consists of three polypeptide subunits: alpha (Mr approximately 260,000), beta 1 (Mr approximately 39,000), and beta 2 (Mr approximately 37,000)--exhibits the same voltage dependence, neurotoxin sensitivity, and ionic selectivity associated with native sodium channels.