Wang M H, Oh U, Rhee H I
Department of Life Science, Pohang University of Science and Technology, Pohang, Kyun-Buk, 790-784, Korea.
Biochem Biophys Res Commun. 2000 Sep 7;275(3):720-4. doi: 10.1006/bbrc.2000.3369.
To investigate of the gating properties in the voltage-activated potassium channel, we have mutated a variety of S2 and S4 residues in the Shaker potassium protein. Results showed that the R365C and R368C, but not the E283C, R362C, R365S, R368S or the ShB-IR, were sensitive to micromolar concentrations of Cd(2+) ions. This indicates that R365 and R368 play a crucial role in the channel gating due to a conformational modulation of the channel structure. Doubly mutated channels of the E283C/R365E and E283C/R368E caused a transient increase in current amplitude, which reached a peak within a few seconds and then decreased toward initial levels, despite the continual presence of Cd(2+). Taken together, our results suggest that E283, R365, and R368 form a network of strong, local, and electrostatic interactions that relate closely to the mechanism of the channel gating.
为了研究电压门控钾通道的门控特性，我们对Shaker钾蛋白中的多种S2和S4残基进行了突变。结果表明，R365C和R368C对微摩尔浓度的Cd(2+)离子敏感，而E283C、R362C、R365S、R368S或ShB-IR则不敏感。这表明R365和R368由于通道结构的构象调节而在通道门控中起关键作用。E283C/R365E和E283C/R368E的双突变通道导致电流幅度短暂增加，尽管Cd(2+)持续存在，但在几秒钟内达到峰值，然后降至初始水平。综上所述，我们的结果表明E283、R365和R368形成了一个紧密相关的强的、局部的和静电相互作用网络，这与通道门控机制密切相关。
