Liu M, Chen T Y, Ahamed B, Li J, Yau K W
Howard Hughes Medical Institute, Baltimore, MD.
Science. 1994 Nov 25;266(5189):1348-54. doi: 10.1126/science.266.5189.1348.
Although several ion channels have been reported to be directly modulated by calcium-calmodulin, they have not been conclusively shown to bind calmodulin, nor are the modulatory mechanisms understood. Study of the olfactory cyclic nucleotide-activated cation channel, which is modulated by calcium-calmodulin, indicates that calcium-calmodulin directly binds to a specific domain on the amino terminus of the channel. This binding reduces the effective affinity of the channel for cyclic nucleotides, apparently by acting on channel gating, which is tightly coupled to ligand binding. The data reveal a control mechanism that resembles those underlying the regulation of enzymes by calmodulin. The results also point to the amino-terminal part of the olfactory channel as an element for gating, which may have general significance in the operation of ion channels with similar overall structures.
尽管已有报道称几种离子通道可被钙调蛋白直接调节，但尚未确凿证明它们能结合钙调蛋白，其调节机制也尚不明确。对受钙调蛋白调节的嗅觉环核苷酸激活阳离子通道的研究表明，钙调蛋白直接结合于该通道氨基末端的一个特定结构域。这种结合降低了通道对环核苷酸的有效亲和力，显然是通过作用于与配体结合紧密偶联的通道门控来实现的。这些数据揭示了一种类似于钙调蛋白对酶调节的控制机制。研究结果还指出，嗅觉通道的氨基末端部分是门控的一个元件，这可能对具有相似整体结构的离子通道的运作具有普遍意义。
