Different G protein-coupled receptor kinases govern G protein and beta-arrestin-mediated signaling of V2 vasopressin receptor.
Signaling through beta-arrestins is a recently appreciated mechanism used by seven-transmembrane receptors. Because G protein-coupled receptor kinase (GRK) phosphorylation of such receptors is generally a prerequisite for beta-arrestin binding, we studied the roles of different GRKs in promoting beta-arrestin- mediated extracellular signal-regulated kinase ( ERK) activation by a typical seven-transmembrane receptor, the Gs-coupled V2 vasopressin receptor. Gs- and beta-arrestin- mediated pathways to ERK activation could be distinguished with H89, an inhibitor of protein kinase A, and beta-arrestin 2 small interfering RNA, respectively. The roles of GRK2, -3, -5, and -6 were assessed by suppressing their expression with specific small interfering RNA sequences. By using this approach, we demonstrated that GRK2 and -3 are responsible for most of the agonist-dependent receptor phosphorylation, desensitization, and recruitment of beta-arrestins. In contrast, GRK5 and -6 mediated much less receptor phosphorylation and beta-arrestin recruitment, but yet appeared exclusively to support beta-arrestin 2- mediated ERK activation. GRK2 suppression actually increased beta-arrestin- stimulated ERK activation. These results suggest that beta-arrestin recruited in response to receptor phosphorylation by different GRKs has distinct functional potentials.[1]References
- Different G protein-coupled receptor kinases govern G protein and beta-arrestin-mediated signaling of V2 vasopressin receptor. Ren, X.R., Reiter, E., Ahn, S., Kim, J., Chen, W., Lefkowitz, R.J. Proc. Natl. Acad. Sci. U.S.A. (2005) [Pubmed]
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