Deficiency in light-dependent opsin phosphorylation in Irish setters with rod-cone dysplasia.
A deficiency in light-dependent opsin phosphorylation and a slight reduction in opsin synthesis were observed during photoreceptor cell development (22-26 days) preceding photoreceptor cell loss in Irish setters with rod-cone dysplasia. In addition to opsin, two other phosphoprotein bands were found associated with the photoreceptor cell layer; synthesis and phosphorylation of one of these (band 3; 44-48 Kd) appeared reduced, while synthesis and phosphorylation of the other (band 1; 29-31 Kd) was within the normal range in 25-day-old affected setters. The deficiency in light-dependent opsin phosphorylation in affected setters was not due to a deficiency in opsin kinase, since soluble proteins from affected or normal outer segments catalyzed equally well opsin phosphorylation in partially kinase-depleted outer segment membranes from normal, while both kinase preparations failed to promote light-dependent opsin phosphorylation in those from affected setters. A deficiency in light-dependent opsin phosphorylation was also observed in rd/rd mice at all ages studied. In contrast, in Royal College of Surgeons (RCS) rats, light-dependent opsin phosphorylation was within the normal range prior to photoreceptor loss, and became nondetectable only after 50% or more of the photoreceptors had degenerated.
D000818:Animals; D006152:Cyclic GMP / Q000378:metabolism; D004285:Dogs; D004586:Electrophoresis; D005136:Eye Proteins / Q000378:metabolism*; D051606:G-Protein-Coupled Receptor Kinase 1; D010766:Phosphorylation; D010786:Photoreceptor Cells / Q000378:metabolism*; D011494:Protein Kinases / Q000378:metabolism; D011869:Radioligand Assay; D012162:Retinal Degeneration / Q000378:metabolism*; D017299:Rod Opsins
D005136:Eye Proteins; D017299:Rod Opsins; D011494:Protein Kinases; D051606:G-Protein-Coupled Receptor Kinase 1; D006152:Cyclic GMP