A study on the inactivation of voltage-gated potassium channels.

电压门控钾通道是允许钾离子跨膜通量的大分子孔。大多数钾离子通道进入失活状态，不允许离子渗透。本文研究了克隆的电压门控钾离子通道（两个apilsia通道，aKvl）失活的分子机制。la & aKv5.1，以及一个大鼠通道rkv1 .4)。aKvl。la和rKvl。4个是同源通道，两个通道都表现出明显的失活，称为累积失活。然而，当从内到外观察通道电流时，这两个通道显示出显著的对比；aKvl的累积失活。la表达增强，rKviL4表达抑制。有证据表明，孔道结构参与了累积失活，在孔道区域，8个氨基酸在aKvl之间存在差异。la和rkv .4。因此，aKvl的8个孔突变体。并检测了各突变对爪蟾卵母细胞表达系统的影响。结果表明，aKvl累积失活的差异。la和rKvl。4是由于外口孔的结构不同。为了确认缺乏n型失活通道的结果，我们制作了8个突变体的氨基末端缺失突变体。这种缺失对累积失活的功能后果目前正在调查中。因为aKv5.1完全缺乏失活，我们现在正试图检查aKvl之间的嵌合体通道。la和aKv5.1来描绘失活的重要结构域。

Voltage-gated potassium channels are macromolecular pores, which permit the trans-membrane flux of potassium ions. Most potassium channels enter the inactivated states, which do not permit the permeation of ions. In this study, molecular mechanisms of the inactivation were examined on some cloned voltage-gated potassium channels (two Aplysia channels, aKvl.la & aKv5.1, and a rat channel, rKvl.4). aKvl.la and rKvl.4 are homologous channels, and both channels show a prominent inactivation called the accumulative inactivation. When the channel currents were examined in inside-out patches, however, these two channels showed a remarkable contrast ; the accumulative inactivation of aKvl.la was enhanced, while that of rKviL4 depressed. There are some evidence which suggest the involvement of pore structure in the accumulative inactivation, and indeed, in the pore region of the channels, 8 amino acids are different between aKvl.la and rKvl.4. Therefore, eight pore mutants of aKvl.la were made, and the effects of each mutation were examined in Xenopus oocyte expression system. The results suggest that the difference of the accumulative inactivation of aKvl.la and rKvl.4 is due to the different structure of the external mouth of the pore. To confirm the results in the channels that lack N-type inactivation, the amino-terminal deletion mutants of the eight mutants were made. The functional consequence of such deletion on the accumulative inactivation is currently under investigation. Because aKv5.1 lacks the inactivation at all, we are now trying to examine the chimera channels between aKvl.la and aKv5.1 to delineate the important domains for the inactivation.