Rhodopsin, light-sensor of vision

IF 18.6 1区 医学 Q1 OPHTHALMOLOGY
Klaus Peter Hofmann , Trevor D. Lamb
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引用次数: 13

Abstract

The light sensor of vertebrate scotopic (low-light) vision, rhodopsin, is a G-protein-coupled receptor comprising a polypeptide chain with bound chromophore, 11-cis-retinal, that exhibits remarkable physicochemical properties. This photopigment is extremely stable in the dark, yet its chromophore isomerises upon photon absorption with 70% efficiency, enabling the activation of its G-protein, transducin, with high efficiency. Rhodopsin's photochemical and biochemical activities occur over very different time-scales: the energy of retinaldehyde's excited state is stored in <1 ps in retinal-protein interactions, but it takes milliseconds for the catalytically active state to form, and many tens of minutes for the resting state to be restored. In this review, we describe the properties of rhodopsin and its role in rod phototransduction. We first introduce rhodopsin's gross structural features, its evolution, and the basic mechanisms of its activation. We then discuss light absorption and spectral sensitivity, photoreceptor electrical responses that result from the activity of individual rhodopsin molecules, and recovery of rhodopsin and the visual system from intense bleaching exposures. We then provide a detailed examination of rhodopsin's molecular structure and function, first in its dark state, and then in the active Meta states that govern its interactions with transducin, rhodopsin kinase and arrestin. While it is clear that rhodopsin's molecular properties are exquisitely honed for phototransduction, from starlight to dawn/dusk intensity levels, our understanding of how its molecular interactions determine the properties of scotopic vision remains incomplete. We describe potential future directions of research, and outline several major problems that remain to be solved.

视紫红质,视觉的光传感器
视紫红质是一种g蛋白偶联受体,由一条多肽链和结合的发色团11-顺式视网膜组成,具有显著的物理化学性质。这种光色素在黑暗中非常稳定,但它的发色团在光子吸收时以70%的效率异构化,从而能够高效地激活其g蛋白,即转导蛋白。视紫红质的光化学和生化活动发生在非常不同的时间尺度上:视黄醛激发态的能量在视黄醛-蛋白相互作用中储存在1ps内,但形成催化活性状态需要几毫秒,恢复静息状态需要几十分钟。本文综述了视紫红质的性质及其在视棒光传导中的作用。我们首先介绍了视紫红质的总体结构特征,它的演变,以及它的激活的基本机制。然后,我们讨论了光吸收和光谱灵敏度,由单个视紫红质分子活性引起的光感受器电反应,以及从强烈漂白暴露中恢复视紫红质和视觉系统。然后,我们详细检查了视紫红质的分子结构和功能,首先在其暗状态下,然后在控制其与转导蛋白,视紫红质激酶和阻滞蛋白相互作用的活性元状态下。虽然很明显,从星光到黎明/黄昏强度水平,视紫红质的分子特性被精细地磨练为光导,但我们对其分子相互作用如何决定暗视特性的理解仍然不完整。我们描述了潜在的未来研究方向,并概述了几个仍有待解决的主要问题。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
CiteScore
34.10
自引率
5.10%
发文量
78
期刊介绍: Progress in Retinal and Eye Research is a Reviews-only journal. By invitation, leading experts write on basic and clinical aspects of the eye in a style appealing to molecular biologists, neuroscientists and physiologists, as well as to vision researchers and ophthalmologists. The journal covers all aspects of eye research, including topics pertaining to the retina and pigment epithelial layer, cornea, tears, lacrimal glands, aqueous humour, iris, ciliary body, trabeculum, lens, vitreous humour and diseases such as dry-eye, inflammation, keratoconus, corneal dystrophy, glaucoma and cataract.
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