Identification of a human delta opioid receptor: Cloning and expression

Richard J. Knapp, Ewa Malatynska, Lei Fang, Xiaoping Li, Elizabeth Babin, Michael Nguyen, Giovanna Santoro, Eva V. Varga, Victor J. Hruby, William R. Roeske, Henry I. Yamamura

Research output: Contribution to journalArticlepeer-review

70 Scopus citations


The δ opioid receptor is an important target for analgesic drug development. This report describes the identification of δ opioid receptor clones from human cDNA libraries and the preparation of a human δ 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 δ receptors. COS-7 cells transfected with this clone express over 1.0 pmole receptor/mg protein when measured by saturation binding with [3H]naltrindole. The δ 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 μ and κ opioid receptor ligands CTAP and U-69593, respectively, are over 4.0 μM. 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 δ receptor is of the δ2 subtype.

Original languageEnglish (US)
Pages (from-to)PL463-PL469
JournalLife Sciences
Issue number25
StatePublished - 1994


  • cDNA library
  • endorphin receptors
  • radioligand binding
  • recombinant DNA

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Pharmacology, Toxicology and Pharmaceutics(all)


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