Localization of an endogenous substrate for cyclic AMP-stimulated protein phosphorylation in retina.
Incubation of mouse or rabbit whole retina homogenates in the presence of [gamma 32P]-ATP and Mg2+ leads to the phosphorylation of various proteins, as demonstrated using SDS-polyacrylamide gel electrophoresis and autoradiography. The phosphorylation of one protein (ca. approximately equal to 31000 mol. wt) was increased by cyclic AMP in both species, with half-maximal stimulation at 5 x 10(-7)M. Cyclic GMP was also active, but much less potent. Protein phosphorylation patterns were compared in retina homogenates from normal mice (C57BL/6J), from adult C57BL/6J mice homozygous for the retinal degeneration gene (rd/rd) in which rod photoreceptor cells are absent, and from 21-day-old 020/Cpb mice homozygous for the retinal degeneration slow gene (rds/rds) in which only the outer segments of the rod photoreceptors are missing. The 31 K protein was only present in normal and in 21-day-old rds/rds mice. When rabbit retina was microdissected into outer segment, inner segment plus outer nuclear, and inner retina layers, cyclic AMP-stimulated phosphorylation of the 31 K protein was evident only in the inner segment plus outer nuclear layer. These data indicated the presence of a specific, endogenous substrate for a cAMP-dependent protein kinase which is found in the inner portions of rod photoreceptor cells.
D000818:Animals; D000242:Cyclic AMP / Q000494:pharmacology*; D006152:Cyclic GMP / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D005136:Eye Proteins / Q000378:metabolism*; D066298:In Vitro Techniques; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D011817:Rabbits; D012160:Retina / Q000187:drug effects / Q000378:metabolism*; D012162:Retinal Degeneration / Q000378:metabolism; D013268:Stimulation, Chemical
D005136:Eye Proteins; D010750:Phosphoproteins; D000242:Cyclic AMP; D006152:Cyclic GMP