Phosphorylation of teleost phosducins and its effect on the affinity to G-protein beta gamma subunits |
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Authors: | Kobayashi Yuko Hisatomi Osamu Tokunaga Fumio |
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Affiliation: | Department of Earth and Space Science, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan. |
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Abstract: | 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. |
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Keywords: | Phosducin Teleost Medaka (Oryzias latipes) G-protein beta gamma subunits Protein kinase A Ca2+/calmodulin-dependent kinase II |
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