...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >Block of Shaker potassium channels by external calcium ions
【24h】

Block of Shaker potassium channels by external calcium ions

机译：外部钙离子阻止振动筛钾通道

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

We describe an interaction between external Ca2+ ions and Shaker K channels that is important in the gating of the channels. The interaction was first detected as a partial block of inward K+ current in elevated Ca2+, beginning near -40 mV and becoming stronger at more negative voltage. Surprisingly, the time course of the block can be resolved as a rapid decay of inward current magnitude following a repolarizing step. The rapid decay of current is shown to be the result of channel block by using a two-pulse procedure that monitors the time course of gate closing. As a result of block, the decay of the tail current after repolarization is two to three times faster than gate closing. With physiological values for voltage and calcium concentration, block is readily detectable from tail time course, implying that it occurs as a normal concomitant of gate closing in Shaker. The slight voltage dependence of block from -60 to -100 mV suggests that Ca2+ is bound (with low affinity) near the outer mouth of the channel. Elevated calcium quickens the inward gating current recorded as Shaker channels are closing; this current approximately doubles in amplitude and has a faster time course and quicker rising phase. When combined, the results suggest that calcium accelerates the first step in closing of the channel gate, perhaps by changing the channel's ion-occupancy state. [References: 19]
机译：我们描述了外部Ca2 +离子与Shaker K通道之间的相互作用，这在通道门控中很重要。相互作用首先被检测为升高的Ca2 +中的部分内向K +电流，开始在-40 mV附近开始，并在更多负电压时变得更强。出人意料的是，该块的时间进程可以解决为在重新极化步骤之后内向电流幅度的快速衰减。电流的快速衰减显示为通过使用两个脉冲过程监控通道关闭时间过程的通道阻塞的结果。由于阻塞，重新极化后的尾电流衰减比栅极关闭快两到三倍。利用电压和钙浓度的生理值，可以很容易地从尾部时间进程中检测到阻塞，这表明它是在振荡器中关闭闸门的正常伴随现象。从-60到-100 mV的阻断电压依赖性很小，表明Ca2 +在通道的外口附近被结合（低亲和力）。当振动筛通道关闭时，钙离子升高会加速记录的内向门控电流。该电流的幅度大约翻倍，并且具有更快的时间过程和更快的上升阶段。结合使用后，结果表明钙可能通过改变通道的离子占有状态来加速关闭通道门的第一步。 [参考：19]

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号