NMR with GPCRs

Summary

G protein-coupled receptors (GPCRs) are integral membrane proteins that transmit extracellular neural, endocrine, olfactory and visual signals across the plasma membrane. When activated by light or a ligand GPCRs undergo a conformational change leading to activation of a G protein, arrestin and other signaling pathways. Over 30% of compounds used in medicine today modulate the activity of GPCRs. Some GPCRs can bind a range of ligands, some of which, instead of fully activating the receptor, rather bias the signal transduction cascade toward distinct intracellular pathways.
The currently available X-ray structures of several GPCRs and of a beta2-adrenoreceptor/Gs signaling complex provide a frozen snapshot of a signal transduction event, but do not fully explain how the ligand selectivity is achieved, and how the ligand binding results in preferential binding of a specific signaling protein such as Gi, Gs or arrestin. Understanding the precise structural and dynamic nature of these phenomena is critical to knowing the mechanism of GPCR activation and will help further development of pharmaceuticals with desired pharmacological properties.
We want to provide the missing dynamical information on GPCR function by Nuclear Magnetic Resonance spectroscopy (NMR), which shall determine the conformational changes and dynamics of the receptors and signaling complexes in solution. This should then yield a comprehensive view of GPCR activation and signal transduction. We will initially focus on rhodopsin and the beta1-adrenoreceptor (beta1AR), as well as their signaling complexes with G proteins and arrestin, and later apply the developed expertise to the vasopressin receptor V2R and its signaling complexes.
In particular, we will: a) label GPCRs for NMR analysis; b) obtain a dynamic view of the conformational changes in GPCRs induced by a range of ligands with different activities including agonists, antagonists and biased ligands; c) investigate the effect of G proteins and arrestin binding on the receptors; d) identify the molecular basis for signaling selectivity via a comparative NMR and biophysical analysis of receptor binding to the various ligands, G proteins and arrestin.

Index Terms

Membrane protein, dynamics, antagonist, signaling, arrestin.

Supported By

Schweizerischer Nationalfonds

In Collaboration With

Prof. G. Schertler, Prof. F. Allain, Prof. S. Grzesiek, Dr. D. Veprintsev, Jakob Jorgensen