Avdonin V, Hoshi T
Department of Physiology and Biophysics, The University of Iowa, Iowa City, Iowa 52242, USA.
Biophys J. 2001 Jul;81(1):97-106. doi: 10.1016/S0006-3495(01)75683-4.
Indole constitutes a major component of the side chain of the amino acid tryptophan. Application of indole slows activation of voltage-dependent potassium channels and reduces steady-state conductance in a voltage- and concentration-dependent manner. The steep concentration dependence indicates that multiple indole molecules may interact with the channel. Indole does not noticeably change the unitary conductance or the mean open duration, however, it accelerates off-gating currents without altering on-gating currents. These properties of the modification of channel gating induced by indole are consistent with a model in which indole binds independently to every subunit of the channel complex to prevent the final concerted transition to the open state. We suggest that exogenously applied indole and side-chains of the tryptophan residues of the channel protein involved in activation may compete for the same effector position and that indole might be useful as a probe to study functional roles of tryptophan residues.
吲哚是氨基酸色氨酸侧链的主要组成部分。应用吲哚会减缓电压依赖性钾通道的激活，并以电压和浓度依赖性方式降低稳态电导。陡峭的浓度依赖性表明多个吲哚分子可能与通道相互作用。然而，吲哚不会显著改变单位电导或平均开放持续时间，它会加速关闭门控电流而不改变开启门控电流。吲哚诱导的通道门控修饰的这些特性与一个模型一致，在该模型中，吲哚独立地结合到通道复合物的每个亚基上，以防止最终协同转变为开放状态。我们认为，外源性应用的吲哚和参与激活的通道蛋白色氨酸残基的侧链可能竞争相同的效应物位置，并且吲哚可能作为研究色氨酸残基功能作用的探针。
