Characterization of the carboxyl terminal-truncated endothelin B receptor coexpressed with G protein-coupled receptor kinase 2. |
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Authors: | T Shibasaki K Moroi M Nishiyama J Zhou A Sakamoto T Masaki K Ito T Haga S Kimura |
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Affiliation: | Department of Biochemistry and Molecular Pharmacology, Chiba University Graduate School of Medicine, Japan. |
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Abstract: | The role of phosphorylation of the C-terminal tail of endothelin B receptor (ETBR) in agonist-induced desensitization was investigated, using a mutant lacking C-terminal 40 amino acids (delta 40 ETBR). In cells expressing the wild type or delta 40 ETBR, ET-1 caused rapid desensitization of calcium responses. The wild type ETBR was phosphorylated by biotinylated ET-1, and the phosphorylation was markedly enhanced by coexpression with G protein-coupled receptor kinase 2 (GRK2). However, delta 40 ETBR was not phosphorylated regardless of coexpression with GRK2. On the other hand, ET-1-induced IP3 formation in these cells was decreased by coexpression with GRK2 or catalytically inactive Lys220Arg GRK2 to the similar extent. The present study demonstrates the presence of phosphorylation-independent desensitization mechanism in delta 40 ETBR and suggests that GRK2 might play a role other than that as a kinase. |
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