Phosphorylation of teleost phosducins and its effect on the affinity to G-protein beta gamma subunits.
Phosducin (PD) is a regulatory protein involved in the phototransduction cascade of vertebrate photoreceptor cells. We have previously demonstrated that there are rod- and cone-specific PDs (OlPD-R and OlPD-C) in the retina of the teleost fish, medaka (Oryzias latipes) [FEBS Lett. 502 (2001) 117]. A 6x His affinity precipitation assay revealed that phosphorylation by either protein kinase A (PKA) or Ca(2+)/calmodulin-dependent kinase II (CaMKII) reduced the affinity of recombinant medaka PDs to endogenous medaka G-protein beta gamma subunits (Gbetagamma). These results suggest that the affinity of medaka PDs to Gbetagamma is regulated by cAMP and Ca(2+) concentrations as also found for mammalian PDs. However, we found a specific difference in the phosphorylation patterns between recombinant OlPD-R and OlPD-C, which resulted in different affinities to Gbetagamma. These differences may affect the light/dark-adaptation between medaka rods and cones.
Department of Earth and Space Science, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan.
Yuko
Y
Kobayashi
Osamu
O
Hisatomi
Fumio
F
Tokunaga
D000818:Animals; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D005136:Eye Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D020555:GTP-Binding Protein Regulators; D044387:GTP-Binding Protein beta Subunits / Q000378:metabolism*; D044388:GTP-Binding Protein gamma Subunits / Q000378:metabolism*; D009990:Oryzias / Q000378:metabolism*; D010750:Phosphoproteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D010766:Phosphorylation; D011994:Recombinant Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*
D005136:Eye Proteins; C118981:G-protein Beta gamma; D020555:GTP-Binding Protein Regulators; D044387:GTP-Binding Protein beta Subunits; D044388:GTP-Binding Protein gamma Subunits; D010750:Phosphoproteins; D011994:Recombinant Proteins; C065631:phosducin; D017868:Cyclic AMP-Dependent Protein Kinases; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases