C-Terminal Membrane Association of Bestrophin 3 and Its Activation as a Chloride Channel
C-Terminal Membrane Association of Bestrophin 3 and Its Activation as a Chloride Channel
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Bestropin 3 的 C 端膜关联及其作为氯离子通道的激活
DOI：
10.1007/s00232-012-9514-7
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发表时间：
2013-02-01
影响因子：
2.4
通讯作者：
Jiang, Hong
中科院分区：
文献类型：
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作者：
Han, Xiaohua;Qu, Zhiqiang;Jiang, Hong
Bestropin 3 (Best3) 是 bestropin Cl- 通道家族的成员，是血管平滑肌细胞中 cGMP 敏感、Ca2+ 激活的 Cl- 通道的候选者。最近发现 Best3 通道在血管舒缩中发挥着重要作用。然而，其激活机制尚未阐明。在之前的研究中，我们发现Best3 C端序列（氨基酸353-404）与细胞膜相关。该序列包括自动抑制结构域((356)IPSFLGS(362))和下游碱性残基结构域(氨基酸384-397)。在这项研究中，我们发现两个结构域之间的序列 (368-383) 实际上是 Best3 C 端膜关联性的决定因素。删除该序列几乎消除了膜关联，但没有激活 Best3 通道。用 PI3K α 抑制剂 IV（Best3 激活剂）处理表达 Best3 的 HEK293 细胞不能消除但削弱了 Best3 膜关联。结果支持这样的假设：Best3 C 末端带正电的碱性残基可能与膜带负电的磷脂相关，磷脂在 Best3 激活的调节中发挥作用。但膜关联性和 Best3 激活之间的关系似乎比预期更复杂。
Bestrophin 3 (Best3), a member of the bestrophin Cl- channel family, is a candidate of cGMP-sensitive, Ca2+-activated Cl- channel in vascular smooth muscle cells. The Best3 channel was recently found to play an important role in vasomotion. However, the mechanism for its activation has not been clarified. In previous studies, we found that a Best3 C-terminal sequence (amino acids 353-404) was associated with the cellular membrane. The sequence includes an autoinhibitory domain ((356)IPSFLGS(362)) and a downstream basic residue domain (amino acids 384-397). In this study, we found that the sequence (368-383) between the two domains is actually a determinant for Best3 C-terminal membrane associability. Deletion of the sequence almost abolished the membrane association but did not activate the Best3 channel. Treatment of Best3-expressing HEK293 cells with the PI3K alpha inhibitor IV (a Best3 activator) could not abolish but weakened the Best3 membrane association. The result supports the assumption that the positively charged basic residues in the Best3 C terminus are likely associated with the membranous negatively charged phospholipids, which plays a role in the regulation of Best3 activation. But the relationship between membrane associability and Best3 activation seems more complicated than expected.