Gandhi Chris S, Clark Eliana, Loots Eli, Pralle Arnd, Isacoff Ehud Y
Department of Molecular and Cell Biology, 271 LSA, MC#3200, University of California, Berkeley, CA 94720, USA.
Neuron. 2003 Oct 30;40(3):515-25. doi: 10.1016/s0896-6273(03)00646-9.
Voltage-gated channels operate through the action of a voltage-sensing domain (membrane segments S1-S4) that controls the conformation of gates located in the pore domain (membrane segments S5-S6). Recent structural studies on the bacterial K(v)AP potassium channel have led to a new model of voltage sensing in which S4 lies in the lipid at the channel periphery and moves through the membrane as a unit with a portion of S3. Here we describe accessibility probing and disulfide scanning experiments aimed at determining how well the K(v)AP model describes the Drosophila Shaker potassium channel. We find that the S1-S3 helices have one end that is externally exposed, S3 does not undergo a transmembrane motion, and S4 lies in close apposition to the pore domain in the resting and activated state.
电压门控通道通过电压感应结构域（膜片段S1 - S4）的作用来运作，该结构域控制位于孔道结构域（膜片段S5 - S6）中的门控结构的构象。最近对细菌K(v)AP钾通道的结构研究产生了一种新的电压感应模型，其中S4位于通道外周的脂质中，并与一部分S3作为一个整体穿过膜。在这里，我们描述了旨在确定K(v)AP模型对果蝇Shaker钾通道描述程度的可及性探测和二硫键扫描实验。我们发现，S1 - S3螺旋的一端向外暴露，S3不发生跨膜运动，并且在静息和激活状态下S4都与孔道结构域紧密相邻。
