ANALYSIS OF A NOVEL DOUBLE-BARRELED ANION CHANNEL FROM RAT-LIVER ROUGH ENDOPLASMIC-RETICULUM
ANALYSIS OF A NOVEL DOUBLE-BARRELED ANION CHANNEL FROM RAT-LIVER ROUGH ENDOPLASMIC-RETICULUM
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DOI：
10.1016/s0006-3495(94)80519-3
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发表时间：
1994-08-01
影响因子：
3.4
通讯作者：
SAUVE, R
中科院分区：
文献类型：
--
作者：
MORIER, N;SAUVE, R
从大鼠肝细胞中分离的剥粗面内质网膜中存在阴离子通道，通过将这些膜的微粒体融合到平面脂质双层来研究。观察到几种类型的阴离子选择性通道，包括电压门控Cl-通道，其活性在450 mM（顺式）50 mM（反式）KCl条件下以爆发形式出现，其特征在于分别在0 pS（0水平）、160 pS（O-1水平）和320 pS（O-2水平）的三个不同电导水平之间的转换。对省略突发间静默期的电流记录的卡方检验（2）分析表明，电流水平0（基线）、0、和0的相对概率遵循二项式统计。然而，条件概率W（pi处的水平0/0处的水平O-2）和W（Pl处的水平0 -2/0处的水平0）提供了电流水平0和0 -2之间的直接跃迁的清楚证据，而没有任何可检测到的到中间水平0 -1的跃迁。基于这些结果得出结论，所观察到的通道由至少两个不同的门控过程控制，即1）电压依赖性激活机制，其中整个系统表现为两个160 pS的独立单体通道，每个通道的特征在于简单的开-闭动力学，和2）缓慢的电压依赖性过程，其解释了通道活性爆发之间的沉默期的出现和电流水平0和0之间的转变。最后，分析了系统处于0级、O-1级和O-2级的相对概率，表明，我们的结果是更兼容的模型，其中所有的国家产生的两个独立的单体通道的叠加有不同的速率访问一个共同的失活状态比一个模型，其中一个简单的开放，关闭的主门同时封闭或暴露两个独立的160 pS单体。
The presence of anionic channels in stripped rough endoplasmic reticulum membranes isolated from rat hepatocytes was investigated by fusing microsomes from these membranes to a planar lipid bilayer. Several types of anion-selective channels were observed including a voltage-gated Cl- channel, the activity of which appeared in bursts characterized by transitions among three distinct conductance levels of 0 pS (0 level), 160 pS (O-1 level), and 320 pS (O-2 level), respectively, in 450 mM (cis) 50 mM (trans) KCI conditions. A chi(2) analysis on current records where interburst silent periods were omitted showed that the relative probability of current levels 0 (baseline), 0,, and 0, followed a binomial statistic. However, measurements of the conditional probabilities W(level 0 at pi/level O-2 at 0) and W(level O-2 at pi/level 0 at 0) provided clear evidence of direct transitions between the current levels 0 and O-2 without any detectable transitions to the intermediate level O-1, It was concluded on the basis of these results that the observed channel was controlled by at least two distinct gating processes, namely 1) a voltage-dependent activation mechanism in which the entire system behaves as two independent monomeric channels of 160 pS with each channel characterized by a simple Open-Closed kinetic, and 2) a slow voltage-dependent process that accounts for both the appearance of silent periods between bursts of channel activity and the transitions between the current levels O and 0,. Finally, an analysis of the relative probability for the system to be in levels 0, O-1, and O-2, showed that our results are more compatible with a model in which all the states resulting from the superposition of the two independent monomeric channels have access at different rates to a common inactivated state than with a model where a simple Open-Closed main gate either occludes or exposes simultaneously two independent 160-pS monomers.