Developing a novel fluorescent antagonist binding assay to probe the ligand binding sites of the human Gastrin Releasing Peptide receptor (360G-Wellcome-202176_Z_16_Z)

Fluorescent ligands are an innovative approach to the study of receptor molecular pharmacology,capable of replacing radioactive tools in studies of binding and cellular localisation of unmodifiedreceptors, and also of exploring the dynamics of ligand-receptor interaction through high resolutionimaging approaches. The purpose of this project is to characterise novel fluorescent antagonistsfor the gastrin releasing peptide (GRP) G protein coupled receptor (synthesised by University ofNottingham collaborators), a peptide messenger system implicated in gastrointestinal, immune andCNS functions such as neural processing of itch. Desi will then develop a live cell platereaderimaging assay, based on competition binding with the fluorescent ligands, to measure affinities ofrepresentative GRPR agonists and antagonists. Finally, the effects of alanine scanning mutation ina key region of the receptor implicated in ligand binding (extracellular loop 3) will be determined.These individual goals will dovetail with a wider funded international programme of work on theGRP receptor. Binding and receptor mutagenesis studies will feed into molecular modelling work byBrazilian colleagues to characterise GRP receptor antagonist binding sites, in order to betterunderstand the rationale design of these ligands as potential therapeutics for cancer, inflammationand analgesia.