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Receptors, Channels and Transporters:
Development and Application of Novel Technologies for Structure Determination

Final Report Summary - EMPSI (Receptors, Channels and Transporters:Development and Application of Novel Technologies for Structure Determination)

The overall aim of the project was a deeper understanding of the structure and function of G protein-coupled receptors through a combination of structural biology and high-throughput screening of receptor mutants for all functionalities (folding, stability, antagonist binding, agonist binding, G protein-coupling, arrestin coupling, basal activity). We have made significant progress in all these areas.

A key enabling technology was developed at the start of the project with the development of mini-G proteins for Gi, Go and Gq, based on our previous work in engineering mini-Gs. These stabilised G proteins proved crucial for the structure determination of receptors in the fully active state, including the adenosine A2A receptor (two different structures), serotonin 5-HT1B receptor, angiotensin receptor and rhodopsin. This has deepened our understanding of how G proteins couple to GPCRs, the different determinants for coupling Go, Gs and Gq G proteins, and also the effect they have on the orthosteric binding pocket. The high-resolution cryo-EM structure of β-arrestin coupled the β1AR showed for the first time the differences between how β-arrestin coupled compared to a G protein, and their different effects on the orthosteric binding pocket. Development of a screening procedure for GPCR libraries using a fluorescent agonist identified all the important amino acid residues that lead to high affinity agonist binding.