title: Functional domains of delta- and mu-opioid receptors responsible for adenylyl cyclase inhibition.
abstract: Opioid receptors (delta, mu) belong to the large superfamily of G protein coupled receptors that inhibit adenylyl cyclase. We have studied the effects of seven synthetic peptides representing selected cytoplasmic regions of the murine delta-opioid receptor on forskolin-mediated adenylyl cyclase activity in membranes of D2 and Neuro(2A) cells stably expressing the delta- and mu-opioid receptors respectively. The entire third intracellular loop (i3), its amino-terminal portion (i3.1) and the carboxyl-terminal region of the second cytoplasmic loop (i2.2) enhanced dose-dependently the agonist-mediated inhibition of cAMP accumulation. The peptide-mediated effects are blocked by pertussis toxin treatment and are not observed in parental cells that lack these receptors. The inhibitory effects of the peptides on adenylyl cyclase were markedly attenuated when membranes from D2 and Neuro(2A) cells were preincubated with antisera against Gi(2) alpha and G beta subunits of G proteins. Our results provide evidence on domains of the delta- and mu-opioid receptors responsible for adenylyl cyclase inhibition.
authors.affiliation: Institute of Biology, The National Centre for Scientific Research Demokritos, 15310 Ag. Paraskevi, Athens, Greece.
authors.forename: G
authors.initials: G
authors.lastname: Megaritis
authors.forename: M
authors.initials: M
authors.lastname: Merkouris
authors.forename: Z
authors.initials: Z
authors.lastname: Georgoussi
mesh_terms: D000067956:Adenylyl Cyclase Inhibitors; D000818:Animals; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism; D051960:GTP-Binding Protein alpha Subunit, Gi2; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000378:metabolism; D051379:Mice; D010446:Peptide Fragments / Q000494:pharmacology*; D010455:Peptides / Q000494:pharmacology*; D017434:Protein Structure, Tertiary; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051381:Rats; D017465:Receptors, Opioid, delta / Q000819:agonists / Q000378:metabolism*; D017450:Receptors, Opioid, mu / Q000819:agonists / Q000378:metabolism*
chemical_list: D000067956:Adenylyl Cyclase Inhibitors; D010446:Peptide Fragments; D010455:Peptides; D011518:Proto-Oncogene Proteins; D017465:Receptors, Opioid, delta; D017450:Receptors, Opioid, mu; D005576:Colforsin; D000242:Cyclic AMP; D019204:GTP-Binding Proteins; D051960:GTP-Binding Protein alpha Subunit, Gi2; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; C498016:Gnai2 protein, mouse; C498017:Gnai2 protein, rat