Molecular mechanism underlying phosphatidylinositol 4,5-bisphosphate-induced inhibition of SpIH channels.
Molecular mechanism underlying phosphatidylinositol 4,5-bisphosphate-induced inhibition of SpIH channels.
复制标题
DOI：
10.1074/jbc.m110.214650
复制
发表时间：
2011-04-29
期刊：
影响因子：
--
通讯作者：
Zagotta WN
中科院分区：
文献类型：
--
作者：
Flynn GE;Zagotta WN
许多离子通道已被证明是由膜信号磷脂磷脂酰肌醇4，5-二磷酸（PIP 2）。在这里，我们证明了PIP 2与海胆超极化激活的环核苷酸门控离子通道（HCN）SpIH的结合具有双重作用：增强和抑制。观察到的电位作为一个移动的电压依赖性的激活更多的去极化电压。观察到的抑制是部分激动剂cGMP引起的电流减少。这两种效应是可分离的，并且是由PIP 2结合到两个不同区域引起的。SpIH的C-末端区域的缺失去除了PIP 2诱导的抑制，但没有去除PIP 2诱导的电压依赖性偏移。突变的关键带正电荷的氨基酸在C-末端区域相邻的膜选择性地破坏PIP 2诱导的抑制，这表明PIP 2在膜和氨基酸之间的直接相互作用的C-末端区域，稳定相对于HCN通道的开放状态的关闭状态。
Many ion channels have been shown to be regulated by the membrane signaling phospholipid phosphatidylinositol 4,5-bisphosphate (PIP2). Here, we demonstrate that the binding of PIP2 to SpIH, a sea urchin hyperpolarization-activated cyclic nucleotide-gated ion channel (HCN), has a dual effect: potentiation and inhibition. The potentiation is observed as a shift in the voltage dependence of activation to more depolarized voltages. The inhibition is observed as a reduction in the currents elicited by the partial agonist cGMP. These two effects were separable and arose from PIP2 binding to two different regions. Deletion of the C-terminal region of SpIH removed PIP2-induced inhibition but not the PIP2-induced shift in voltage dependence. Mutating key positively charged amino acids in the C-terminal region adjacent to the membrane selectively disrupted PIP2-induced inhibition, suggesting a direct interaction between PIP2 in the membrane and amino acids in the C-terminal region that stabilizes the closed state relative to the open state in HCN channels.