title: Endomorphin-1 and endomorphin-2 are partial agonists at the human mu-opioid receptor.
abstract: Recently two tetrapeptide ligands that bind preferentially to the mu-opioid receptor were identified and named endomorphin-1 and endomorphin-2. We examined the ability of these peptides to stimulate G protein activation in human mu-opioid receptor transfected B82 fibroblasts as measured by [35S]GTPgammaS binding to cell membranes. Both endomorphin-1 and -2 act as partial agonists in this assay system compared with the mu-selective agonist [D-Ala2,N-Me-Phe4, Gly-ol5]enkephalin (DAMGO). In addition, endomorphins demonstrate efficacy similar to morphine. These findings demonstrate that endomorphin peptides have similar activity at the mu-opioid receptor as morphine and suggest that these peptides have the potential to modulate neuronal activity in vivo.
authors.affiliation: Department of Pharmacology, University of Arizona, Tucson 85724, USA.
authors.forename: K
authors.initials: K
authors.lastname: Hosohata
authors.forename: T H
authors.initials: TH
authors.lastname: Burkey
authors.forename: J
authors.initials: J
authors.lastname: Alfaro-Lopez
authors.forename: E
authors.initials: E
authors.lastname: Varga
authors.forename: V J
authors.initials: VJ
authors.lastname: Hruby
authors.forename: W R
authors.initials: WR
authors.lastname: Roeske
authors.forename: H I
authors.initials: HI
authors.lastname: Yamamura
mesh_terms: D000701:Analgesics, Opioid / Q000494:pharmacology*; D002460:Cell Line; D019204:GTP-Binding Proteins / Q000378:metabolism; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000378:metabolism; D006801:Humans; D009842:Oligopeptides / Q000494:pharmacology*; D017450:Receptors, Opioid, mu / Q000819:agonists*
chemical_list: D000701:Analgesics, Opioid; D009842:Oligopeptides; D017450:Receptors, Opioid, mu; C105293:endomorphin 1; D016244:Guanosine 5'-O-(3-Thiotriphosphate); C105294:endomorphin 2; D019204:GTP-Binding Proteins