Ca2+-activated Cl- current from human bestrophin-4 in excised membrane patches.
Ca2+-activated Cl- current from human bestrophin-4 in excised membrane patches.
复制标题
Ca2+激活的Cl-在切除的膜斑中的人类Bestrophin-4的电流。
DOI：
10.1085/jgp.200609527
复制
发表时间：
2006-06
影响因子：
3.8
通讯作者：
Yau, King-Wai
中科院分区：
文献类型：
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作者：
Tsunenari, Takashi;Nathans, Jeremy;Yau, King-Wai
Bestrophins是一个新发现的Cl−通道家族，其中一些成员被细胞内Ca 2+激活。到目前为止，所有的研究都是用质粒转染的培养细胞的全细胞记录进行的，因此尚不清楚Ca 2+是否通过代谢机制或更直接的方式激活雌激素。我们在这里报告的实验，解决了这个问题与切除，由内而外的膜补丁。我们选择人类雌激素-4（hBest 4）进行异源表达，因为它在表达时产生特别大的Cl−电流，因此即使在切除的膜斑中也可以检测到。hBest 4在细胞质（浴）侧的无Ca 2+溶液中产生可忽略的Cl−电流，但产生的Cl−电流以剂量依赖性方式被Ca 2+激活，K 1/2为230 nM。因此，Ca 2+似乎激活了雌激素Cl−通道，而不通过自由扩散的信使或蛋白磷酸化。然而，由于激活和失活动力学非常缓慢，我们不能排除膜相关信使的参与。
Bestrophins are a newly discovered family of Cl− channels, some members of which are activated by intracellular Ca2+. So far, all studies were carried out with whole-cell recordings from plasmid-transfected cultured cells, so it is unclear whether Ca2+ activates bestrophin through a metabolic mechanism or in a more direct way. We report here experiments that addressed this question with excised, inside-out membrane patches. We chose human bestrophin-4 (hBest4) for heterologous expression because it gave particularly large Cl− currents when expressed, thus allowing detection even in excised membrane patches. hBest4 gave a negligible Cl− current in a Ca2+-free solution on the cytoplasmic (bath) side, but produced a Cl− current that was activated by Ca2+ in a dose-dependent manner, with a K 1/2 of 230 nM. Thus, Ca2+ appears to activate the bestrophin Cl− channel without going through a freely diffusible messenger or through protein phosphorylation. Because the activation and deactivation kinetics were very slow, however, we cannot exclude the involvement of a membrane-associated messenger.