Cyclic GMP and photoreceptor function
Cyclic GMP and photoreceptor function
复制标题
循环 GMP 和光感受器功能
DOI：
10.1096/fasebj.4.12.1697545
复制
发表时间：
1990
期刊：
影响因子：
--
通讯作者：
Rehwa H. Lee
中科院分区：
文献类型：
--
作者：
R. Lolley;Rehwa H. Lee
单个光子可以被视杆细胞检测到。视紫红质对光的吸收触发放大光子信号的级联反应，并导致离子通道关闭，使视杆细胞超极化。视紫红质的光诱导构象变化促进鸟苷核苷酸结合蛋白转导素的结合，其然后经历aGTP-GDP交换反应和转导素复合物的解离。然后，转导素的亚基激活水解环GMP的磷酸二酯酶复合物。在黑暗中，环GMP与感光细胞质膜的阳离子通道结合，使它们保持开放构型。光诱导的环GMP浓度降低使结合的环GMP解离，导致通道关闭和超极化。级联的下调涉及阻断转导素与视紫红质的相互作用的其他蛋白质和可能干扰转导素再循环的另一种蛋白质。视锥光感受器具有遵循杆状形式的光激活级联，但它由与杆状光感受器的蛋白质同源的蛋白质组成。无脊椎动物光感受器中的光转导使用视紫红质来激活级联反应，该级联反应使用磷酸肌醇和钙离子来调节膜极化。洛利河N.的;利河，巴西-地H.环磷酸鸟苷与光感受器功能FASEB J. 4：3001 - 3008; 1990年。
A single photon can be detected by a rod photoreceptor cell. The absorption of light by rhodopsin triggers a cascade of reactions that amplifies the photon signal and results in ion channel closure with hyperpolarization of the rod photoreceptor cell. Light‐induced conformational changes in rhodopsin facilitate the binding of a guanosine nucleotide‐binding protein, transducin, which then undergoes aGTP‐GDP exchange reaction and dissociation of the transducin complex. A subunit of transducin then activates a phosphodiesterase complex that hydrolyzes cyclic GMP. In darkness, cyclic GMP binds to cation channels of the photoreceptor plasma membrane, maintaining them in an open configuration. The light‐induced reduction in cyclic GMP concentration dissociates the bound cyclic GMP, resulting in channel closure and hyperpolarization. Down‐regulation of the cascade involves other proteins that block the interaction of transducin with rhodopsin and another protein that may interfere with transducin recycling. Cone photoreceptors possess a light‐activated cascade that follows the rod format, but it is composed of proteins that are homologous to those of rod photoreceptors. Phototransduction in invertebrate photoreceptors uses rhodopsin to activate a cascade that uses phosphoinositides and calcium ion to regulate membrane polarization.— Lolley, R. N.; Lee, R. H. Cyclic GMP and photoreceptor function. FASEB J. 4: 3001‐3008; 1990.