Synthesis of the all-trans-retinal chromophore of retinal G protein-coupled receptor opsin in cultured pigment epithelial cells.
Synthesis of the all-trans-retinal chromophore of retinal G protein-coupled receptor opsin in cultured pigment epithelial cells.
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在培养的色素上皮细胞中合成视网膜 G 蛋白偶联受体视蛋白的全反式视网膜发色团。
DOI：
10.1074/jbc.m108946200
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发表时间：
2002
期刊：
影响因子：
--
通讯作者：
Fong,HenryKW
中科院分区：
文献类型：
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作者：
Yang,Mao;Fong,HenryKW
视网膜色素上皮（RPE）的11-顺式-视黄醛的光依赖性产生和在光条件下视紫红质的正常再生涉及RPE视网膜G蛋白偶联受体（RGR）视蛋白。该微粒体视蛋白与全反式-视网膜结合，其在光照下立体特异性地异构化为11-顺式异构体。在本文中，我们研究了在培养的ARPE-hRGR和新鲜分离的牛RPE细胞中RGR的全反式视网膜发色团的合成。外源性全反式-[3 H]视黄醇被掺入完整的RPE细胞，并主要转化为视黄酯和全反式-视黄醇。全反式-[3 H]视黄醇的细胞内加工导致与放射性标记的类维生素A（鉴定为全反式-[3 H]视黄醛）的RGR的生理结合。ARPE-hRGR细胞含有膜结合的NADPH依赖性视黄醇脱氢酶，其有效地与全反式视黄醇反应，但不与11-顺式异构体反应。在离体的RPE微粒体膜中，NADPH依赖的全反式视黄醇脱氢酶活性可与发色团与RGR的体外特异性结合相关联。这些发现证实了RGR视蛋白在黑暗中与发色团全反式视网膜结合。一种新的全反式视黄醇脱氢酶存在于RPE中，在发色团生物合成中起关键作用。
Light-dependent production of 11-cis-retinal by the retinal pigment epithelium (RPE) and normal regeneration of rhodopsin under photic conditions involve the RPE retinal G protein-coupled receptor (RGR) opsin. This microsomal opsin is bound to all-trans-retinal which, upon illumination, isomerizes stereospecifically to the 11-cisisomer. In this paper, we investigate the synthesis of the all-trans-retinal chromophore of RGR in cultured ARPE-hRGR and freshly isolated bovine RPE cells. Exogenous all-trans-[3H]retinol is incorporated into intact RPE cells and converted mainly into retinyl esters and all-trans-retinal. The intracellular processing of all-trans-[3H]retinol results in physiological binding to RGR of a radiolabeled retinoid, identified as all-trans-[3H]retinal. The ARPE-hRGR cells contain a membrane-bound NADPH-dependent retinol dehydrogenase that reacts efficiently with all-trans-retinol but not the 11-cisisomer. The NADPH-dependent all-trans-retinol dehydrogenase activity in isolated RPE microsomal membranes can be linkedin vitroto specific binding of the chromophore to RGR. These findings provide confirmation that RGR opsin binds the chromophore, all-trans-retinal, in the dark. A novel all-trans-retinol dehydrogenase exists in the RPE and performs a critical function in chromophore biosynthesis.