CONDUCTION PROPERTIES OF THE CLONED SHAKER K+ CHANNEL
CONDUCTION PROPERTIES OF THE CLONED SHAKER K+ CHANNEL
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DOI：
10.1016/s0006-3495(93)81244-x
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发表时间：
1993-11-01
影响因子：
3.4
通讯作者：
MACKINNON, R
中科院分区：
文献类型：
--
作者：
HEGINBOTHAM, L;MACKINNON, R
利用电生理技术研究了克隆的Shaker K+通道的传导特性。单通道电导以亚线性方式增加，K+活性对称增加，0.6 M K+达到饱和。Shaker K+通道对一价阳离子具有高度选择性;在双离子条件下，其选择性顺序为K+ > Rb+ > NH 4 + > Cs+ > Na+，而在对称溶液中，其相对电导率为K+ > NH 4 + > Rb+ > Cs+。在Cs+溶液中，单通道电流太小而不能直接测量，因此使用非平稳波动分析来确定单位Cs+电导。单通道电导在K+和NH 4+的对称混合物中显示出异常的摩尔分数效应，表明导电孔同时被多个离子占据。
The conduction properties of the cloned Shaker K+ channel were studied using electrophysiological techniques. Single channel conductance increases in a sublinear manner with symmetric increases in K+ activity, reaching saturation by 0.6 M K+. The Shaker K+ channel is highly selective among monovalent cations; under bi-ionic conditions, its selectivity sequence is K+ > Rb+ > NH4+ > Cs+ > Na+, whereas, by relative conductance in symmetric solutions, it is K+ > NH4+ > Rb+ > Cs+. In Cs+ solutions, single channel currents were too small to be measured directly, so nonstationary fluctuation analysis was used to determine the unitary Cs+ conductance. The single channel conductance displays an anomalous mole-fraction effect in symmetric mixtures of K+ and NH4+ suggesting that the conducting pore is occupied by multiple ions simultaneously.