Ligand-receptor interactions of Gonadotropin-releasing hormone antagonists
type: CreativeWork
description: The interactions of selected GnRH agonists and antagonists with the GnRH receptor were investigated using site directed mutagenesis and photoaffinity cross/inking of the receptor with a labelled GnRH analog. With the aim of identifying residues involved in ligand binding, the relative affinities of five peptide and one non-peptide GnRH antagonists towards three closely related mammalian GnRH receptors (mouse, sheep and human) were determined using cells transiently expressing GnRH receptors. All of the peptide antagonists [Ac-3-Pro 1 , D-4- F-Phe2 , 2-D-Naf, D-lpr-Lys6 , /pr-Lys8 ]GnRH, [2-Ac-D-NaJ1, D-Me-4-CI-Phe, 3-D-Paf, D-Arg6 , D-AlaNH2 10JGnRH, [2-Ac-D-NaJ1, D-4-CI-Phe2 , 3-D-Paf, Nic-Lys5 , D-Nic-Lys6 , /pr-Lys8 , D-AlaNH/0 JGnRH, [Ac-D-NaJ1, D-4-CI-Phe2 , D-Paf, D-Lys(3-pAc)6, lpr-Lys8 , D-AlaNH2 10JGnRH and [2-Ac-D-NaJ1, D-4-CI-Phe2 , 3-D-Paf, 1-Me-Paf, D-Trp6 , DAlaNH2 10JGnRH were found to have a higher potency for the inhibition of GnRH stimulated inositol phosphate by the mouse and sheep receptors than by human GnRH receptor. The greatest differences in affinity were exhibited by the antagonist, [2-Ac-D-NaJ1, D-Me-4-CI-Phe, 3-D-Paf, D-Arg6 , D-AlaNH2 10]GnRH. This antagonist showed an affinity difference of 54 fold between mouse and human receptors and 68 fold between sheep and human receptors. These results suggest that mutation of residues which differ between human and sheep receptors could be used to identify specific residue(s) involved in the binding of this peptide antagonist. This line of investigation was not pursued further, however, in view of more promising possibilities with non-peptide antagonists. FE 101170, a non-peptide GnRH antagonist was found to have 300-fold higher affinity for the human receptor than the sheep receptor. The regions of the receptor responsible for the differential affinity were explored using point-mutated and human/sheep chimeric GnRH receptors. These receptors had one or more residue of the human GnRH receptor rep…
abstract: The interactions of selected GnRH agonists and antagonists with the GnRH receptor were investigated using site directed mutagenesis and photoaffinity cross/inking of the receptor with a labelled GnRH analog. With the aim of identifying residues involved in ligand binding, the relative affinities of five peptide and one non-peptide GnRH antagonists towards three closely related mammalian GnRH receptors (mouse, sheep and human) were determined using cells transiently expressing GnRH receptors. All of the peptide antagonists [Ac-3-Pro 1 , D-4- F-Phe2 , 2-D-Naf, D-lpr-Lys6 , /pr-Lys8 ]GnRH, [2-Ac-D-NaJ1, D-Me-4-CI-Phe, 3-D-Paf, D-Arg6 , D-AlaNH2 10JGnRH, [2-Ac-D-NaJ1, D-4-CI-Phe2 , 3-D-Paf, Nic-Lys5 , D-Nic-Lys6 , /pr-Lys8 , D-AlaNH/0 JGnRH, [Ac-D-NaJ1, D-4-CI-Phe2 , D-Paf, D-Lys(3-pAc)6, lpr-Lys8 , D-AlaNH2 10JGnRH and [2-Ac-D-NaJ1, D-4-CI-Phe2 , 3-D-Paf, 1-Me-Paf, D-Trp6 , DAlaNH2 10JGnRH were found to have a higher potency for the inhibition of GnRH stimulated inositol phosphate by the mouse and sheep receptors than by human GnRH receptor. The greatest differences in affinity were exhibited by the antagonist, [2-Ac-D-NaJ1, D-Me-4-CI-Phe, 3-D-Paf, D-Arg6 , D-AlaNH2 10]GnRH. This antagonist showed an affinity difference of 54 fold between mouse and human receptors and 68 fold between sheep and human receptors. These results suggest that mutation of residues which differ between human and sheep receptors could be used to identify specific residue(s) involved in the binding of this peptide antagonist. This line of investigation was not pursued further, however, in view of more promising possibilities with non-peptide antagonists. FE 101170, a non-peptide GnRH antagonist was found to have 300-fold higher affinity for the human receptor than the sheep receptor. The regions of the receptor responsible for the differential affinity were explored using point-mutated and human/sheep chimeric GnRH receptors. These receptors had one or more residue of the human GnRH receptor rep…
author: Assefa, Daniel
keywords: Pathology
date published: 1999
date modified: 2026-07-22T22:23:14Z
provider: University of Cape Town
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Department of Pathology

PropertyValue
property ID: Handle
value: http://hdl.handle.net/11427/40031