A new hyperpolarization-activated, cyclic nucleotide-gated channel from sea urchin sperm flagella
A new hyperpolarization-activated, cyclic nucleotide-gated channel from sea urchin sperm flagella
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DOI：
10.1016/j.bbrc.2005.06.074
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发表时间：
2005-08-19
影响因子：
3.1
通讯作者：
Vacquier, VD
中科院分区：
文献类型：
--
作者：
Galindo, BE;Neill, AT;Vacquier, VD
已知海胆精子鞭毛超极化激活的环核苷酸门控（HCN）通道（SpHCN 1）受cAMP调节。在这里，我们描述了第二鞭毛HCN通道（SpHCN 2）克隆从同一种海胆。SpHCN 2由638个氨基酸组成，而SpHCN 1由767个氨基酸组成。SpHCN 2具有HCN通道的所有结构域，包括六个跨膜区段（S1-S6）、离子孔和环核苷酸结合结构域。这两个全长蛋白质有33%相同，51%相似。六个跨膜区段的同一性在46-79%之间变化。作为电压传感器的S4在两种蛋白质之间具有79%的相同性。离子选择性过滤器序列在SpHCN 1的离子孔中为GYG，在SpHCN 2中为GFG。通过测序，SpHCN 2为73.5 kDa，但它在SDS-PAGE上迁移到64 kDa。Western免疫印迹显示定位于鞭毛，这通过免疫荧光证实。相邻连接树显示SpHCN 2是所有已知HCN通道的基础。SpHCN 2可能是迄今发现的最简单的起搏通道。(c)2005年爱思唯尔公司All rights reserved.
A sea urchin sperm flagellar hyperpolarization-activated, cyclic nucleotide-gated (HCN) channel is known (SpHCN1) that is modulated by cAMP. Here, we describe a second flagellar HCN channel (SpHCN2) cloned from the same sea urchin species. SpHCN2 is 638 amino acids compared to 767 for SpHCN1. SpHCN2 has all the domains of an HCN channel, including six transmembrane segments (S1-S6), the ion pore, and the cyclic nucleotide-binding domain. The two full-length proteins are 33% identical and 51% similar. The six transmembrane segments vary from 46-79% identity. S4, which is the voltage sensor, is 79% identical between the two proteins. The ion selectivity filter sequence is GYG in the ion pore of SpHCN1 and GFG in SpHCN2. By sequence, SpHCN2 is 73.5 kDa, but it migrates on SDS-PAGE at 64 kDa. Western immunoblots show localization to flagella, which is confirmed by immunofluorescence. A neighbor-joining tree shows that SpHCN2 is basal to all known HCN channels. SpHCN2 might be the simplest pacemaker channel yet discovered. (c) 2005 Elsevier Inc. All rights reserved.