Journal
JOURNAL OF BIOLOGICAL CHEMISTRY
Volume 284, Issue 22, Pages 15038-15051Publisher
AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC
DOI: 10.1074/jbc.M900388200
Keywords
-
Categories
Funding
- NINDS
Ask authors/readers for more resources
We investigated the role of G protein-coupled receptor kinase (GRK)-mediated phosphorylation in agonist-induced desensitization, arrestin association, endocytosis, and intracellular trafficking of the D-2 dopamine receptor (DAR). Agonist activation of D-2 DARs results in rapid and sustained receptor phosphorylation that is solely mediated by GRKs. A survey of GRKs revealed that only GRK2 or GRK3 promotes D-2 DAR phosphorylation. Mutational analyses resulted in the identification of eight serine/threonine residues within the third cytoplasmic loop of the receptor that are phosphorylated by GRK2/3. Simultaneous mutation of these eight residues results in a receptor construct, GRK(-), that is completely devoid of agonist-promoted GRK-mediated receptor phosphorylation. We found that both wild-type (WT) and GRK(-) receptors underwent a similar degree of agonist-induced desensitization as assessed using [S-35]GTP gamma S binding assays. Similarly, both receptor constructs internalized to the same extent in response to agonist treatment. Furthermore, using bioluminescence resonance energy transfer assays to directly assess receptor association with arrestin3, we found no differences between the WT and GRK(-) receptors. Thus, phosphorylation is not required for arrestin-receptor association or agonist-induced desensitization or internalization. In contrast, when we examined recycling of the D-2 DARs to the cell surface, subsequent to agonist-induced endocytosis, the GRK(-) construct exhibited less recycling in comparison with the WT receptor. This impairment appears to be due to a greater propensity of the GRK(-) receptors to down-regulate once internalized. In contrast, if the receptor is highly phosphorylated, then receptor recycling is promoted. These results reveal a novel role for GRK-mediated phosphorylation in regulating the post-endocytic trafficking of a G protein-coupled receptor.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available