Involvement of amino acids flanking Glu7.32 of the Gonadotropin-releasing hormone receptor in the selectivity of antagonists

Chengbing Wang, Dayoung Oh, Kaushik Maiti, Hyuk Bang Kwon, Jun Cheon, Jong Ik Hwang, Jae Young Seong

Research output: Contribution to journalArticlepeer-review


The Glu/Asp7.32 residue in extracellular loop 3 of the mammalian type-I gonadotropin-releasing hormone receptor (GnRHR) interacts with Arg8 of GnRH-I, conferring preferential ligand selectivity for GnRH-I over GnRH-II. Previously, we demonstrated that the residues (Ser and Pro) flanking Glu/Asp7.32 also play a role in the differential agonist selectivity of mammalian and non-mammalian GnRHRs. In this study, we examined the differential antagonist selectivity of wild type and mutant GnRHRs in which the Ser and Pro residues were changed. Cetrorelix, a GnRH-I antagonist, and Trptorelix-2, a GnRH-II antagonist, exhibited high selectivity for mammalian type-I and non-mammalian GnRHRs, respectively. The inhibitory activities of the antagonists were dependent on agonist concentration and subtype. Rat GnRHR in which the Ser-Glu-Pro (SEP) motif was changed to Pro-Glu-Val (PEV) or Pro-Glu-Ser (PES) had increased sensitivity to Trptorelix-2 but decreased sensitivity to Cetrorelix. Mutant bullfrog GnRHR-1 with the SEP motif had the reverse antagonist selectivity, with redueed sensitivity to Trptorelix-2 but increased sensitivity to Cetrorelix. These findings indicate that the residues flanking Glu7.32 are important for antagonist as well as agonist selectivity.

Original languageEnglish (US)
Pages (from-to)91-98
Number of pages8
JournalMolecules and Cells
Issue number1
StatePublished - Feb 29 2008


  • Antagonist selectivity
  • Extracellular loop 3 (ECL3)
  • G protein-coupled receptor (GPCR)
  • GnRH receptor
  • Gonad-otropin-releasing hormone (GnRH)
  • Ser-Glu-Pro (SEP) motif

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology


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