Phosphorylated mu-opioid receptor purified from rat brains lacks functional coupling with Gi1, a GTP-binding protein in reconstituted lipid vesicles.
The effects of phosphorylation of a mu-opioid receptor on signal transduction to G-protein were studied. The mu-opioid receptor purified from rat whole brains was reconstituted with purified Gi1 in phosphatidylcholine vesicles. DAGO, a mu-opioid agonist at 1 microM-1 mM increased GTPase activity by 10-110% of control, in a concentration-dependent manner. When the mu-opioid receptor was phosphorylated by cyclic AMP-dependent protein kinase prior to reconstitution with Gi1, the DAGO-stimulation was markedly reduced (20% increase at 1 mM DAGO).
Harada
H
H
Department of Pharmacology, Faculty of Pharmaceutical Sciences, Kyoto University, Japan.
Ueda
H
H
Katada
T
T
Ui
M
M
Satoh
M
M
D000818:Animals; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D004745:Enkephalins / Q000494:pharmacology*; D019204:GTP-Binding Proteins / Q000378:metabolism / Q000502:physiology*; D008081:Liposomes; D010713:Phosphatidylcholines; D010766:Phosphorylation; D051381:Rats; D011919:Rats, Inbred Strains; D011957:Receptors, Opioid / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D017450:Receptors, Opioid, mu; D015398:Signal Transduction
D004745:Enkephalins; D008081:Liposomes; D010713:Phosphatidylcholines; D011957:Receptors, Opioid; D017450:Receptors, Opioid, mu; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D019204:GTP-Binding Proteins