Ondek B, Hardy R W, Baker E K, Stamnes M A, Shieh B H, Zuker C S
Howard Hughes Medical Institute, La Jolla, California.
J Biol Chem. 1992 Aug 15;267(23):16460-6.
Cyclophilins, the intracellular receptors for the widely used immunosuppressant cyclosporin A have been found to be peptidyl-prolyl cis/trans isomerases and have been implicated in intracellular protein folding and trafficking. The Drosophila ninaA gene encodes a photoreceptor-specific cyclophilin homolog involved in rhodopsin biogenesis. ninaA mutants have a 90% reduction in the levels of Rh1 rhodopsin. To gain insight into the role of cyclophilins in vivo, we carried out a genetic screen designed to identify functionally important regions in the ninaA protein. Over 700,000 mutagenized flies were screened for a visible ninaA phenotype and 70 independent mutations in ninaA were isolated and characterized. These mutations provide a detailed dissection of the structure/function relationships in cyclophilin. We also show that mammalian cyclophilins engineered to contain missense mutations found in two temperature-sensitive ninaA alleles display temperature-sensitive prolyl cis/trans isomerase activity.
亲环蛋白是广泛使用的免疫抑制剂环孢菌素A的细胞内受体，已被发现是肽基脯氨酰顺/反异构酶，并与细胞内蛋白质折叠和运输有关。果蝇ninaA基因编码一种参与视紫红质生物合成的光感受器特异性亲环蛋白同源物。ninaA突变体中Rh1视紫红质水平降低了90%。为了深入了解亲环蛋白在体内的作用，我们进行了一项遗传筛选，旨在确定ninaA蛋白中功能重要的区域。对超过70万只诱变果蝇进行了可见的ninaA表型筛选，分离并鉴定了ninaA中的70个独立突变。这些突变详细剖析了亲环蛋白的结构/功能关系。我们还表明，经过工程改造以包含在两个温度敏感的ninaA等位基因中发现的错义突变的哺乳动物亲环蛋白表现出温度敏感的脯氨酰顺/反异构酶活性。
