Multimerization of the ligand binding domains of cyclic nucleotide-gated channels
Multimerization of the ligand binding domains of cyclic nucleotide-gated channels
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DOI：
10.1016/s0896-6273(02)00878-4
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发表时间：
2002-09-26
期刊：
影响因子：
16.2
通讯作者：
Zagotta, WN
中科院分区：
文献类型：
--
作者：
Matulef, K;Zagotta, WN
环核苷酸门控(CNG)通道由四个亚基组成，由环核苷酸直接与每个亚基上的胞内结构域结合而激活。这个配体结合域被认为包含一个β卷曲，后面跟着两个阿尔法螺旋，称为B和C螺旋。为了研究CNG通道的四级结构以及它在离子通道门控过程中的变化，我们在一个原本没有半胱氨酸的通道中，沿着每个亚基的C螺旋引入了单半胱氨酸。我们发现C螺旋上的半胱氨酸可以形成亚基间的二硫键，甚至斜角亚基之间的二硫键。二硫键的形成主要发生在封闭的通道中，抑制了通道的开放。这些数据表明，所有四个通道亚基的C螺旋在关闭状态下非常接近，在通道打开时则分开。
Cyclic nucleotide-gated (CNG) channels comprise four subunits and are activated by the direct binding of cyclic nucleotide to an intracellular domain on each subunit. This ligand binding domain is thought to contain a beta roll followed by two alpha helices, designated the B and C helices. To examine the quaternary structure of CNG channels and how it changes during ion channel gating, we introduced single cysteines along the C helix of each subunit in an otherwise cysteineless channel. We found that cysteines on the C helices could form intersubunit disulfide bonds, even between diagonal subunits. Disulfide bond formation occurred primarily in closed channels and inhibited channel opening. These data suggest that the C helices from all four channel subunits are in close proximity in the closed state and move apart during channel opening.