Light-dependent in vivo phosphorylation of an inhibitory subunit of cGMP-phosphodiesterase in frog rod photoreceptor outer segments.
In vivo phosphorylation of P gamma, an inhibitory subunit of cGMP-phosphodiesterase of frog (Rana catesbeiana) photoreceptor rod outer segments, was investigated using a quick-freezing technique and a newly developed method for the preparation of rod outer segments. Light-dependent phosphorylation of P gamma was observed. Okadaic acid, a potent inhibitor of protein phosphatases 1 and 2A, enhanced the apparent incorporation of 32P into P gamma, suggesting that P gamma is in equilibrium between phosphorylation and dephosphorylation. Neither phorbol ester, a potent activator of protein kinase C, nor changes in the extracellular Ca2+ concentration affected the in vivo phosphorylation of P gamma.
Hayashi
F
F
Department of Biology, Faculty of Science, Kobe University, Japan.
D015106:3',5'-Cyclic-GMP Phosphodiesterases / Q000378:metabolism*; D000818:Animals; D015180:Electrophoresis, Gel, Two-Dimensional; D008027:Light; D010710:Phosphates / Q000378:metabolism; D010761:Phosphorus Radioisotopes; D010766:Phosphorylation; D010786:Photoreceptor Cells / Q000201:enzymology*; D011892:Rana catesbeiana; D012374:Rod Cell Outer Segment / Q000201:enzymology*
D010710:Phosphates; D010761:Phosphorus Radioisotopes; D015106:3',5'-Cyclic-GMP Phosphodiesterases