All-trans to 11-cis retinol isomerization in nuclear membrane fraction from bovine retinal pigment epithelium

Abstract Isomerization of all-trans to 11-cis retinol has been studied in a membrane preparation from the nuclear fraction of bovine retinal pigment epithelium. When the nuclear membrane preparation deprived of endogenous retinoids is incubated with 4·5 μ m all-trans-retinol, the mean value calculated for the isomerase activity is 1·32 nmol 11-cis retinol formed hr−1 mg protein−1. Simultaneous formation of all-trans and 11-cis retinyl esters is also observed in the nuclear preparation. When assayed under the same experimental condition, RPE 150 000 g post-nuclear sediment shows about 70% of the isomerase activity found in the nuclear membrane fraction. Treatment of the nuclear membrane frac…