Shedding new light on the generation of the visual chromophore
Shedding new light on the generation of the visual chromophore
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DOI：
10.1073/pnas.2008211117
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发表时间：
2020-08-18
影响因子：
11.1
通讯作者：
Kiser, Philip D.
中科院分区：
文献类型：
--
作者：
Palczewski, Krzysztof;Kiser, Philip D.
视觉光传导级联反应始于与视杆和视锥光感受器的视色素相关的亚视黄基发色团的顺-反光异构化。视蛋白在光活化后释放其全反式视网膜发色团，这需要存在产生11-顺式-视网膜的途径以持续形成视色素和维持视力。视网膜色素上皮（RPE）（邻近光感受器外节的细胞层）中的蛋白质形成被称为经典视觉周期的完善的“暗”再生途径。该途径足以维持连续的视杆细胞功能并支持视锥细胞光感受器，尽管其通量必须通过额外的机制来增强，以在面对高速率的光子捕获时维持色素水平。最近的研究表明，经典的视觉周期与RPE和神经视网膜中的光依赖性过程一起工作，以确保在自然照度下能够跨越十个数量级的足够的11-顺式-视网膜产生。进一步阐明这些互补系统之间的相互作用是理解视锥细胞介导的视觉是如何在体内维持的基础。在这里，我们描述了最近的进展，了解如何通过光依赖性机制合成11-顺式-视网膜。
The visual phototransduction cascade begins with a cis-trans photoisomerization of a retinylidene chro-mophore associated with the visual pigments of rod and cone photoreceptors. Visual opsins release their all-trans-retinal chromophore following photoactivation, which necessitates the existence of pathways that produce 11-cis-retinal for continued formation of visual pigments and sustained vision. Proteins in the retinal pigment epithelium (RPE), a cell layer adjacent to the photoreceptor outer segments, form the well -established "dark" regeneration pathway known as the classical visual cycle. This pathway is sufficient to maintain continuous rod function and support cone photoreceptors as well although its throughput has to be augmented by additional mechanism(s) to maintain pigment levels in the face of high rates of photon capture. Recent studies indicate that the classical visual cycle works together with light-dependent pro-cesses in both the RPE and neural retina to ensure adequate 11-cis-retinal production under natural illu-minances that can span ten orders of magnitude. Further elucidation of the interplay between these complementary systems is fundamental to understanding how cone-mediated vision is sustained in vivo. Here, we describe recent advances in understanding how 11-cis-retinal is synthesized via light-dependent mechanisms.