The steric trigger in rhodopsin activation.
The steric trigger in rhodopsin activation.
复制标题
视紫红质激活的空间触发因素。
DOI：
10.1006/jmbi.1997.1035
复制
发表时间：
1997
期刊：
影响因子：
--
通讯作者：
Smith,SO
中科院分区：
文献类型：
--
作者：
Shieh,T;Han,M;Sakmar,TP;Smith,SO
Rhodopsin is the seven transmembrane helix receptor responsible for dim light vision in vertebrate rod cells. The protein has structural homology with the other G protein-coupled receptors, which suggests that the tertiary structures and activation mechanisms are likely to be similar. However, rhodopsin is unique in several respects. The most striking is the fact that the receptor “ligand”, 11-cis retinal, is covalently bound to the protein and is converted from an “antagonist” to an “agonist” upon absorption of light. NMR studies of rhodopsin and its primary photoproduct, bathorhodopsin, have generated structural constraints that enabled docking of the 11-cis and all-trans retinal chromophores into a low-resolution model of the protein proposed by Baldwin. These studies also suggest a mechanism for how retinal isomerization leads to rhodopsin activation. More recently, mutagenesis studies have extended these results by showing how the selectivity of the retinal-binding site can be modified to favor the all-trans over the 11-cis isomer. The structural constraints produced from these studies, when placed in the context of a high-resolution model of the protein, provide a coherent picture of the activation mechanism, which we show involves a direct steric interaction between the retinal chromophore and transmembrane helix 3 in the region of Gly121.
