Regulation of rhodopsin kinase by autophosphorylation.

AUTOR(ES)

Buczyłko, J

RESUMO

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.

Documentos Relacionados

• The tyrosine kinase encoded by the MET proto-oncogene is activated by autophosphorylation.
• Calmodulin binding to the cytoskeletal neuronal calmodulin-dependent protein kinase is regulated by autophosphorylation.
• Binding of calmodulin to the neuronal cytoskeletal protein kinase type II cooperatively stimulates autophosphorylation.
• Potential positive and negative autoregulation of p60c-src by intermolecular autophosphorylation.
• Identification of the alpha beta monomer of the adipocyte insulin receptor by insulin binding and autophosphorylation.