Zagotta W N
Department of Physiology and Biophysics, Howard Hughes Medical Institute, University of Washington, School of Medicine, Seattle 98195-7290, USA.
J Bioenerg Biomembr. 1996 Jun;28(3):269-78. doi: 10.1007/BF02110700.
Cyclic nucleotide-gated (CNG) channels are highly specialized to carry out their unique role in cell signalling. Significant progress has been made in the last several years determining the molecular mechanisms for these specializations. The activation of the channels begins with the binding of cyclic nucleotide to a domain in the carboxyl terminal region. This binding, in turn, produces an induced fit of the protein that involves a movement of the C-helix portion of the binding domain. The induced fit of the binding domain is coupled to an allosteric conformational change that opens the channel pore. The pore is formed primarily from the sequence between the S5 and S6 segments. A single glutamic acid in the pore represents the binding site for multiple monovalent cations, the blocking site for external divalent cations, and the site for the effect of protons on permeation.
环核苷酸门控（CNG）通道高度特化，在细胞信号传导中发挥独特作用。在过去几年中，确定这些特化的分子机制方面取得了重大进展。通道的激活始于环核苷酸与羧基末端区域的一个结构域结合。这种结合反过来会引起蛋白质的诱导契合，其中涉及结合结构域的C螺旋部分的移动。结合结构域的诱导契合与打开通道孔的变构构象变化相偶联。孔主要由S5和S6段之间的序列形成。孔中的单个谷氨酸代表多个单价阳离子的结合位点、外部二价阳离子的阻断位点以及质子对渗透产生影响的位点。
