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Relationship between Ser363 phosphorylation and internalization of the delta opioid receptor
Author(s) -
Bradbury Faye,
Zelnik Jennifer,
Traynor John
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.725.5
Subject(s) - internalization , phosphorylation , agonist , δ opioid receptor , microbiology and biotechnology , opioid receptor , chemistry , receptor , biology , biochemistry
Phosphorylation of Ser363 in the cytoplasmic tail of the delta opioid receptor (DOR) usually precedes receptor internalization, but is not necessarily a prerequisite for internalization. In these studies we measured phosphorylation of DOR Ser363 and DOR internalization in HEK 293 cells stably expressing FLAG‐tagged DOR in response to exposure to a variety of agonists. These agonist‐mediated responses were compared with their efficacy in the [ 35 S]GTPγS assay. The agonists DPDPE and deltorphin were fully efficacious in the [ 35 S]GTPγS assay and produced extensive phosphorylation and internalization. Morphine was a partial agonist in the [ 35 S]GTPγS assay and failed to induce phosphorylation or internalization. In contrast, TAN‐67 a putative DOR1 agonist with a high degree of efficacy in the [ 35 S]GTPγS assay, caused a high degree of Ser363 phosphorylation but very little internalization. A further disconnect between Ser363 phosphorylation and internalization was observed in FLAG‐tagged DOR cells where overexpression of GRK 2, 5, or 6 increased morphine‐induced phosphorylation of DOR Ser363, but did not increase morphine‐induced internalization. Conversely, overexpression of dominant negative GRK2‐K220R decreased DPDPE‐induced internalization. These results confirm a disconnection between phosphorylation of Ser363 and internalization. Supported by DA04087 and DA07261.