Tao Xiao, MacKinnon Roderick
Howard Hughes Medical Institute, Department of Molecular Neurobiology and Biophysics, Rockefeller University, 1230 York Avenue, New York, NY 10065, USA.
J Mol Biol. 2008 Sep 26;382(1):24-33. doi: 10.1016/j.jmb.2008.06.085. Epub 2008 Jul 7.
Voltage-dependent K(+) (Kv) channels play key roles in shaping electrical signaling in both excitable and nonexcitable cells. These channels open and close in response to the voltage changes across the cell membrane. Many studies have been carried out in order to understand the voltage-sensing mechanism. Our laboratory recently determined the atomic structures of a mammalian Kv channel Kv1.2 and a mutant of Kv1.2 named the 'paddle chimera' channel, in which the voltage sensor paddle was transferred from Kv2.1 to Kv1.2. These two structures provide atomic descriptions of voltage-dependent channels with unprecedented clarity. Until now, the functional integrity of these two channels biosynthesized in yeast cells has not been assessed. Here, we report the electrophysiological and pharmacological properties of Kv1.2 and the paddle chimera channels in planar lipid bilayers. We demonstrate that Pichia yeast produce 'normally functioning' mammalian Kv channels with qualitatively similar features to the Shaker K(+) channel in the absence of the N-terminal inactivation gate and that the paddle chimera mutant channel functions as well as Kv1.2. We find, however, that in several respects, the Kv1.2 channel exhibits functional properties that are distinct from Kv1.2 channels reported in the literature.
电压依赖性钾离子（Kv）通道在可兴奋细胞和非可兴奋细胞的电信号形成过程中发挥着关键作用。这些通道会随着细胞膜两侧电压的变化而开启和关闭。为了理解电压传感机制，人们已经开展了许多研究。我们实验室最近确定了一种哺乳动物Kv通道Kv1.2以及一种名为“桨状嵌合体”通道的Kv1.2突变体的原子结构，在该突变体中，电压传感器桨状结构域从Kv2.1转移到了Kv1.2。这两种结构以前所未有的清晰度提供了电压依赖性通道的原子描述。到目前为止，尚未评估在酵母细胞中生物合成的这两种通道的功能完整性。在此，我们报告了Kv1.2和桨状嵌合体通道在平面脂质双分子层中的电生理和药理学特性。我们证明，在没有N端失活门的情况下，毕赤酵母产生的“功能正常”的哺乳动物Kv通道与Shaker钾离子通道具有定性相似的特征，并且桨状嵌合体突变通道的功能与Kv1.2一样好。然而，我们发现，在几个方面，Kv1.2通道表现出与文献中报道的Kv1.2通道不同的功能特性。
