期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1991
卷号：88
期号：6
页码：2568-2572
DOI：10.1073/pnas.88.6.2568
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Rhodopsin kinase (RK) catalyzes the phosphorylation of rhodopsin (Rho) as one of the steps in quenching photoactivated Rho. In this work, we investigated the autophosphorylation of RK and how it affects the interaction between RK and Rho. RK undergoes intramolecular phosphorylation, resulting in the incorporation of three or four phosphates per RK molecule. Phosphorylated RK subsequently is a substrate for protein phosphatases 2A and 2B. We isolated three forms of RK based on their differential interactions with heparin-Sepharose. Fully phosphorylated RK (alpha-RK) binds tightly to Rho but has significantly lower affinity to phosphorylated Rho, whereas unphosphorylated RK (gamma-RK) binds avidly to both forms of Rho. The heterogenous intermediately phosphorylated RK (beta-RK) was not studied. Our data support the hypothesis that RK dissociates from Rho when both Rho and RK become phosphorylated, thereby allowing the binding of arrestin to phosphorylated Rho. These results suggest that autophosphorylation plays an important role in regulating the binding of RK to Rho and that the binding sites of RK and arrestin overlap at least partially.
