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Title: Site-directed mutagenesis studies of the GnRH and TRH receptors of the pituitary gland
Author: Cook, Julia Vanessa Foskett
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1996
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The aim of this thesis was to study the structure-function relationships of the G-protein coupled GnRH receptor and has focused on the identification of key amino acids involved in GnRH receptor-ligand interactions as well as the role of putative disulphide bridge formation within the receptor itself. In addition, the role of disulphide bridges has also been explored in another G-protein coupled receptor (GPCR), the thyrotrophin-releasing hormone (TRH) receptor. Based on primary amino acid sequence data and computer-assisted molecular models, potentially important amino acids were targeted for study. Site-directed mutagenesis was used to substitute targeted amino acids and following expression of mutant receptors in mammalian cells, receptor binding and second messenger function was measured. In GPCRs two conserved extracellular cysteine (Cys) residues have been postulated to form a covalently linked disulphide bridge structure. In the TRH receptor these residues are positioned at Cys98 and Cys179, in the first and second extracellular loops respectively, whilst in the GnRH receptor they are located at analogous positions Cys114 and Cys195. In conclusion putative disulphide bond formation between extracellular cysteine residues in both the GnRH and TRH receptors is important in maintaining tertiary protein structure. In addition amino acids located in TM II and TM VII are essential for the interactions between GnRH and its receptor. Analysis of structure-function relationships, particularly using this dual biochemical and molecular modelling approach, will greatly facilitate rational drug design. In the light of the enormous clinical applications of GnRH and its analogues, information regarding the mechanisms of hormone-receptor interaction will be of benefit in the development of new and novel drug for clinical use in reproductive medicine.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available