Specificity of binding of all-trans-retinyl ester to RPE65.
Specificity of binding of all-trans-retinyl ester to RPE65.
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全反式视黄酯与 RPE65 结合的特异性。
DOI：
10.1021/bi0510779
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发表时间：
2005
期刊：
影响因子：
--
通讯作者：
Rando,RobertR
中科院分区：
文献类型：
--
作者：
Maiti,Pranab;Gollapalli,Deviprasad;Rando,RobertR
膜结合RPE65(MRPE65)是一种与全反式视黄酸酯的结合蛋白，而全反式视黄酸酯是完成视觉循环的异构化反应的底物。RPE65对视紫红质的再生是必不可少的，因此对视力也是如此。由于RPE65似乎是视觉周期中限速通路的一部分，该分子的特定拮抗剂在评估其全部生理作用方面将是重要的。已知该蛋白质立体选择性地结合全反式视黄酸酯(TRES)，解离常数在50 nm范围内。本研究探索RPE65对维甲酸和其他异戊二烯类化合物的整体结合特异性，以努力定义结合的特异性，并开始为其设计特定的拮抗剂的过程。针对TrE分子中的三个主要结构元素(类维A酸基、连接基和酰基部分)的特异性的性质被报道。在全反式视黄酸酯系列中，结合亲和力随脂肪酰基的疏水性而增加。在连接区，天然存在的TrE配体的羧酸酯部分的酰胺、酮和乙醚取代物对结合亲和力影响很小。最后，对全反式维甲酸部分的修饰也是可以容忍的。例如，E，E-法尼基棕榈酸酯与全反式视黄酸棕榈酸酯结合的亲和力大致相同。其他异戊二烯类似物也结合在一起，β-紫罗兰酮系列中截短的维甲酸也是如此。因此，mRPE65是一种针对长链全反式视黄酸酯的中等特异性视黄醇结合蛋白。
Membrane-bound RPE65 (mRPE65) is a binding protein for all-trans-retinyl esters, which are the substrates for the isomerization reaction that completes the visual cycle. RPE65 is essential for rhodopsin regeneration and, hence, for vision. As RPE65 appears to be part of the rate-limiting pathway in the visual cycle, specific antagonists of the molecule will be important in evaluating its full physiological role. The protein is known to stereoselectively bind all-trans-retinyl esters (tREs), with dissociation constants in the 50 nM range. This study explores the overall binding specificity of RPE65 with respect to both retinoids and other isoprenoids in an effort to define the specificity of binding, and to begin the process of designing specific antagonists for it. The nature of the specificity directed toward the three main structural elements (retinoid, linker, and acyl moieties) in the tRE molecule is reported. In the all-trans-retinyl ester series, binding affinity increased as a function of the hydrophobicity of the fatty acyl group. In the linker region, binding affinities were little affected by amide, ketone, and ether replacements for the carboxy ester moiety of the naturally occurring tRE ligand. Finally, modifications in the all-trans-retinoid moiety are also tolerated. For example, E,E-farnesyl palmitate binds with approximately the same affinity as does all-trans-retinyl palmitate. Other isoprenoid analogues also bind, as do truncated retinoids in the β-ionone series. Therefore, mRPE65 is a moderately specific retinoid binding protein directed at long chain all-trans-retinyl esters.