tailieunhanh - Báo cáo khoa học: The variable C-terminal extension of G-protein-coupled receptor kinase 6 constitutes an accessorial autoregulatory domain

G-protein-coupled receptor kinases (GRK) are known to phosphorylate agonist-occupied G-protein-coupled receptors. We expressed and function-ally characterized mouse GRK6 proteins encoded by four distinct mRNAs generated by alternative RNA splicing from a single gene, mGRK6-A to mGRK6-D. | ềFEBS Journal The variable C-terminal extension of G-protein-coupled receptor kinase 6 constitutes an accessorial autoregulatory domain Petra Vatter Claudia Stoesser Ines Samel Peter Gierschik and Barbara Moepps Department of Pharmacology and Toxicology University of Ulm Germany Keywords desensitization G-protein-coupled receptor kinases G-protein-coupled receptors phosphorylation signal transduction Correspondence B. Moepps Department of Pharmacology and Toxicology University of Ulm Albert-Einstein-Allee 11 89081 Ulm Germany Fax 49 731 5002 3872 Tel 49 731 5002 3883 E-mail Petra Vatter and Claudia Stoesser contributed equally to this work. Received 9 August 2005 revised 17 September 2005 accepted 27 September 2005 doi G-protein-coupled receptor kinases GRK are known to phosphorylate agonist-occupied G-protein-coupled receptors. We expressed and functionally characterized mouse GRK6 proteins encoded by four distinct mRNAs generated by alternative RNA splicing from a single gene mGRK6-A to mGRK6-D. Three isoforms mGRK6-A to mGRK6-C differ in their C-ter-minal-most portion which is known to mediate membrane and or receptor interaction and regulate the activity of GRK4-like kinases. One isoform mGRK6-D is identical to the other mGRK6 variants in the N-terminal region but carries an incomplete catalytical domain. Mouse GRK6-D was catalytically inactive and specifically present in the nucleus of transfected cells. Recombinant mouse GRK6-A to mGRK6-C were found to be membrane-associated in cell-free systems and in transfected COS-7 cells suggesting that the very C-terminus of GRK6-A lacking in GRK6-B and mGRK6-C and carrying consensus sites for palmitoylation is not required for membrane interaction. Interestingly the shortest catalytically active variant mGRK6-C was conspicuously more active in phosphorylating light-activated rhodopsin than mGRK6-A and mGRK6-B implying that the C-terminus of the latter two .