Gq-coupled rhodopsin subfamily composed of invertebrate visual pigment and melanopsin
Gq-coupled rhodopsin subfamily composed of invertebrate visual pigment and melanopsin
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DOI：
10.1111/j.1751-1097.2008.00369.x
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发表时间：
2008-07-01
影响因子：
3.3
通讯作者：
Terakita, Akihisa
中科院分区：
文献类型：
--
作者：
Koyanagi, Mitsumasa;Terakita, Akihisa
视紫红质（rhodopsins）及其相关色素在遗传学上至少可分为7个亚家族，这些亚家族也可根据分子功能大致区分。Gq偶联视紫红质亚家族的成员在光吸收时激活Gq型G蛋白，其含有构成视觉和非视觉生理功能的基础的色素。gq偶联的视色素已被发现存在于各种原口动物的横纹感光细胞中，而软体动物和节肢动物的视色素也已被广泛研究。最近，一种新的色素，黑视素，及其同系物已被确定在各种脊椎动物。在哺乳动物中，黑视蛋白定位于视网膜神经节细胞中，并参与非视觉系统，包括昼夜节律诱导和瞳孔光反应。最近，我们在文昌鱼中发现了一种黑视素同系物，文昌鱼是最接近脊椎动物的无脊椎动物。文昌鱼黑视蛋白定位于假定的非视觉感光细胞与横纹肌形态，并表现出分子特性几乎相同的无脊椎动物Gq耦合的视觉色素。文昌鱼黑视蛋白的定位和性质填补了无脊椎动物Gq偶联视色素和脊椎动物昼夜节律性黑视蛋白之间的功能和进化鸿沟。对Gq偶联视紫红质亚家族，特别是无脊椎动物黑视蛋白的研究，将为研究动物进化过程中基于orthopathy基因的各种生理功能的进化提供机会。
Rhodopsins (rhodopsins and their related photopigments) are phylogenetically classified into at least seven subfamilies, which are also roughly discriminated by molecular function. The Gq-coupled rhodopsin subfamily, members of which activate the Gq type G protein upon light absorption, contains pigments which underlie both visual and nonvisual physiologic functions. Gq-coupled visual pigments have been found in the rhabdomeric photoreceptor cells of varied protostomes, and those of molluskans and arthropods have been extensively investigated. Recently, a novel photopigment, melanopsin, and its homologs have been identified in varied vertebrates. In mammals, melanopsin is localized in retinal ganglion cells and is involved in nonvisual systems, including circadian entrainment and pupillary light responses. More recently, we discovered a melanopsin homolog in amphioxus, the closest living invertebrate to vertebrates. Amphioxus melanopsin is localized in putative nonvisual photoreceptor cells with rhabdomeric morphology and exhibits molecular properties almost identical to those of invertebrate Gq-coupled visual pigments. The localization and properties of amphioxus melanopsin bridged the functional and evolutionary gap between invertebrate Gq-coupled visual pigments and vertebrate circadian photopigment melanopsins. Research into the Gq-coupled rhodopsin subfamily, especially invertebrate melanopsins, will provide an opportunity to investigate the evolution of various physiologic functions, based on orthologous genes, during animal evolution.