ABSTRACT

The voltage-sensing phosphatase (VSP) is a unique protein that shows voltage-dependent phosphatase activity toward phosphoinositides. Recently, we reported that VSP is activated and generates polarized PtdIns(4,5)P₂ distribution in sperm flagellum. Interestingly, such specialized PtdIns(4,5)P₂ distribution appears to contribute to the activity of Slo3, a sperm-specific K⁺ channels. It has been already reported that Slo3 activity is upregulated by PtdIns(4,5)P₂ using a heterologous expression system. However, PtdIns(4,5)P₂-dependence of Slo3 activity has not been studied in heterologous expression system in the presence of auxiliary subunit of Slo3, Lrrc52, which drastically changes the electrophysiological property of Slo3. In the present study, we analyzed the regulation of Slo3 activity with Lrrc52 by VSP in Xenopus oocytes. Slo3 with Lrrc52 still exhibited similar sensitivity to VSP activity as Slo3 alone. This finding supports our previous report that VSP regulates Slo3 activity in native sperm flagellum.

摘要

电压感应磷酸酶（VSP）是一种独特的蛋白质，对磷酸肌醇显示出电压依赖性磷酸酶活性。最近，我们报道VSP被激活并在精子鞭毛中产生极化的PtdIns（4,5）P ₂分布。有趣的是，这种专门的PtdIns（4,5）P ₂分布似乎有助于Slo3（精子特异的K ⁺通道）的活性。已经报道了使用异源表达系统，PtdIns（4,5）P ₂上调了Slo3活性。但是，PtdIns（4,5）P ₂Slo3活性的依赖性尚未在Slo3辅助亚基Lrrc52存在的异源表达系统中进行研究，该辅助亚基会极大地改变Slo3的电生理特性。在本研究中，我们分析了非洲爪蟾卵母细胞中VSP对Lrrc52的Slo3活性的调节。具有Lrrc52的Slo3对VSP活性的敏感性仍与单独的Slo3相似。这一发现支持了我们以前的报告，即VSP调节天然精子鞭毛中Slo3的活性。