Reduced rhodopsin phosphorylation during retinal dystrophy.
During inherited retinal dystrophy in Irish Setter dogs, decreased activity of cGMP phosphodiesterase (PDE) results in high cGMP levels and retinal degeneration (1-3). This defect could be in PDE itself, or in its interactions with other proteins of the rod outer segment. We report herein that when retinas from 8-week-old dogs were phosphorylated with gamma-32P-ATP, and separated on SDS-PAGE, phosphorylation of rd dog rhodopsin was reduced. When rd retinas were mixed with normal dog retinas, phosphorylation of the latter was inhibited. Since rd-mediated inhibition was prevented by 1 mM NaF, the results suggest that the cause of reduced rd phosphorylation is increased phosphatase activity. Together, these results demonstrate that decreased phosphorylation of rhodopsin due to increased phosphatase activity is a fundamental biochemical change which may partially account for the degenerative process and loss of visual acuity during inherited retinal dystrophy.
D000818:Animals; D004283:Dog Diseases / Q000378:metabolism*; D004285:Dogs; D010749:Phosphoprotein Phosphatases / Q000378:metabolism; D010766:Phosphorylation; D012160:Retina / Q000378:metabolism; D012162:Retinal Degeneration / Q000378:metabolism / Q000662:veterinary*; D012168:Retinal Pigments / Q000378:metabolism*; D012243:Rhodopsin / Q000378:metabolism*
D012168:Retinal Pigments; D012243:Rhodopsin; D010749:Phosphoprotein Phosphatases