Gating of ion channels made by a diphtheria toxin fragment in phospholipid bilayer membranes.
Gating of ion channels made by a diphtheria toxin fragment in phospholipid bilayer membranes.
复制标题
磷脂双层膜中白喉毒素片段形成的离子通道的门控。
DOI：
10.1073/pnas.80.14.4320
复制
发表时间：
1983
影响因子：
11.1
通讯作者：
Misler,S
中科院分区：
文献类型：
--
作者：
Misler,S
B45，含有白喉毒素的主要疏水区域的片段，通过形成由跨膜电压，Vm和浴pH门控的离子传导通道来增加薄脂质膜的电导。单通道电流显示“突发”行为的形式在封闭和开放的电导水平之间的快速转变。电流“突发”的平均持续时间以及突发内通道实际打开的总时间随着Vm的增加而减少。这些数据的分析表明，在一个范围内的Vm，从开放到封闭状态的转变的速率常数的增加，在很大程度上占宏观电导随着Vm的增加而下降。从闭合电导状态到开放电导状态的转变速率常数的增加更可能是宏观电导随浴pH增加而增加的原因。由于目前可获得几种白喉毒素片段和突变体，每种片段和突变体含有B45区的不同部分，有可能研究这些复杂蛋白质的结构与它们形成的离子通道的详细门控特性之间的关系。
B45, a fragment containing the major hydrophobic region of diphtheria toxin, increases the conductance of thin lipid membranes by forming ion-conducting channels that are gated by transmembrane voltage, Vm, and the bath pH. Single-channel currents show "bursting" behavior in the form of rapid transitions between a closed and an open conductance level. The average duration of a current "burst," as well as the total time a channel is actually open within a burst, decreases with increasing Vm. Analysis of these data suggests that, over a range of Vm, increases in the rate constants for transitions from the open to the closed states largely account for the decline in macroscopic conductance with increasing Vm. Increases in rate constants for transitions from a closed to an open conductance state are more likely to account for the increase in macroscopic conductance with increasing bath pH. Since several diphtheria toxin fragments and mutants are currently available, each containing various portions of the B45 region, it may be possible to study the relationship of the structure of these complex proteins to the detailed gating properties of the ion channels that they form.