Cui J, Kline R P, Pennefather P, Cohen I S
Department of Physiology and Biophysics, State University of New York at Stony Brook 11794-8661.
J Gen Physiol. 1994 Jul;104(1):87-105. doi: 10.1085/jgp.104.1.87.
IsK is a K+ channel of the delayed rectifier type widely distributed throughout both excitable and nonexcitable cells. Its structure is different from other cloned K+ channels and molecular details of its gating remain obscure. Here we show that the activation kinetics of IsK expressed in Xenopus oocytes depend upon the amount of its mRNA injected, with larger amounts resulting in slower activation kinetics with a longer initial delay during activation. Similar changes in activation kinetics occur with time after a single injection of IsK mRNA. We present two kinetic schemes which illustrate how our experimental results could arise. Both imply an interaction among individual channel proteins during IsK activation. The dependence of channel gating on mRNA concentration provides a novel mechanism for long term regulation of ion current kinetics.
IsK是一种延迟整流型钾通道，广泛分布于可兴奋细胞和非可兴奋细胞中。其结构不同于其他已克隆的钾通道，其门控的分子细节仍不清楚。在这里，我们表明在非洲爪蟾卵母细胞中表达的IsK的激活动力学取决于注射的mRNA量，注射量越大，激活动力学越慢，激活时的初始延迟越长。单次注射IsK mRNA后，激活动力学随时间发生类似变化。我们提出了两种动力学方案来说明我们的实验结果是如何产生的。两者都暗示了IsK激活过程中单个通道蛋白之间的相互作用。通道门控对mRNA浓度的依赖性为离子电流动力学的长期调节提供了一种新机制。
