title: Identification of a human delta opioid receptor: cloning and expression.
abstract: The delta opioid receptor is an important target for analgesic drug development. This report describes the identification of delta opioid receptor clones from human cDNA libraries and the preparation of a human delta receptor cDNA in the pcDNA3 expression vector for transfection studies. The cDNA encodes a 372 amino acid protein that has 93% amino acid identity to mouse and rat delta receptors. COS-7 cells transfected with this clone express over 1.0 pmol receptor/mg protein when measured by saturation binding with [3H]naltrindole. The delta receptor selective ligands NTB, BNTX, [4'-Cl-Phe4]DPDPE and [D-Ala2,Glu4]deltorphin all have Ki values under 10 nM while the affinities of the mu and kappa opioid receptor ligands CTAP and U-69593, respectively, are over 4.0 microM. Agonists show binding to multiple affinity states of the receptor consistent with the presence of G-protein coupled and uncoupled forms of the expressed receptor. The 8-fold higher affinity of NTB relative to BNTX suggests that the human delta receptor is of the delta 2 subtype.
authors.affiliation: Department of Pharmacology, University of Arizona College of Medicine, Tucson 85724.
authors.forename: R J
authors.initials: RJ
authors.lastname: Knapp
authors.forename: E
authors.initials: E
authors.lastname: Malatynska
authors.forename: L
authors.initials: L
authors.lastname: Fang
authors.forename: X
authors.initials: X
authors.lastname: Li
authors.forename: E
authors.initials: E
authors.lastname: Babin
authors.forename: M
authors.initials: M
authors.lastname: Nguyen
authors.forename: G
authors.initials: G
authors.lastname: Santoro
authors.forename: E V
authors.initials: EV
authors.lastname: Varga
authors.forename: V J
authors.initials: VJ
authors.lastname: Hruby
authors.forename: W R
authors.initials: WR
authors.lastname: Roeske
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D003001:Cloning, Molecular; D016384:Consensus Sequence; D004745:Enkephalins / Q000378:metabolism; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D009271:Naltrexone / Q000031:analogs & derivatives / Q000378:metabolism; D009292:Narcotic Antagonists / Q000378:metabolism; D009842:Oligopeptides / Q000378:metabolism; D016366:Open Reading Frames; D017465:Receptors, Opioid, delta / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D016415:Sequence Alignment; D014162:Transfection
chemical_list: D004745:Enkephalins; D009292:Narcotic Antagonists; D009842:Oligopeptides; D017465:Receptors, Opioid, delta; C064219:enkephalin, Pen(2,5)-4-chloro-Phe(4)-; C060209:deltorphin II, Ala(2)-; D009271:Naltrexone; C055382:naltrindole