CNPase activity in the vertebrate retina, retinal pigmented epithelium, and choroid

The activity of the enzyme 2',3'-cyclic nucleotide 3'-phosphohydrolase (CNPase, E.C.3.1.4.37) has been studied in the retina of three vertebrate species. Activity was highest in the goldfish, followed by Xenopus laevis and Rana pipiens. Also, high activity levels were found in goldfish retinal pigment epithelium and choroid, but not in the other two species. When added to in vitro culture systems, 2',3'-cyclic nucleotides were found to have no effect on goldfish cone retinomotor movement, but caused a marked inhibition of Rana pipiens rod outer segment disc membrane shedding. It is suggested that CNPase may play a role in cellular processes requiring membrane structural reorganization.