Endomorphin-1 and endomorphin-2 are partial agonists at the human μ- opioid receptor

Keiko Hosohata, Thomas H. Burkey, Josue Alfaro-Lopez, Eva Varga, Victor J. Hruby, William R. Roeske, Henry I. Yamamura

Research output: Contribution to journalArticlepeer-review

59 Scopus citations


Recently two tetrapeptide ligands that bind preferentially to the μ- 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 μ-opioid receptor transfected B82 fibroblasts as measured by [35S]GTPγS binding to cell membranes. Both endomorphin-1 and -2 act as partial agonists in this assay system compared with the μ-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 μ-opioid receptor as morphine and suggest that these peptides have the potential to modulate neuronal activity in vivo.

Original languageEnglish (US)
Pages (from-to)111-114
Number of pages4
JournalEuropean Journal of Pharmacology
Issue number1
StatePublished - Apr 3 1998


  • Efficacy
  • Endomorphin-1
  • Endomorphin-2
  • μ-Opioid receptor

ASJC Scopus subject areas

  • Pharmacology


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