Genetic dissection of cyclophilin function. Saturation mutagenesis of the Drosophila cyclophilin homolog ninaA.
Ondek B., Hardy R.W., Baker E.K., Stamnes M.A., Shieh B.-H., Zuker C.S.
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.
J. Biol. Chem. 267:16460-16466(1992) [ PubMed | SRS | CiteXplore ]
