Rhodopsin phosphorylation in developing normal and degenerative mouse retinas.

The developmental pattern of rhodopsin phosphorylation in degenerative (rdle homozygote) and normal (rd/+ heterozygote) mouse retina has been investigated. The results indicate that rhodopsin levels are comparable in the 2 retinas up to about 10 days of age but that rhodopsin phosphorylation is not. The phosphorylation of rhodopsin is substantially reduced in the degenerative retina during development. This abnormality may be an expression of the rd lesion. The rhodopsin kinase/phosphatase system, the G protein, and the visual pigment are all involved in the modulation of cGMP-phosphodiesterase activity in normal retinas. A defect in any of these components could account for the reduced level of cGMP-phosphodiesterase activity in rd retinas, resulting in cGMP accumulation and subsequent photoreceptor degeneration.