EPR on site-selective spin-labeled human cannabinoid receptor CB2

Cannabinoid receptors belong to the class of G protein-coupled receptors (GPCR) that regulate a multitude of physiological processes by transmitting signals from the extracellular milieu to intracellular proteins. They are primary targets of pharmaceutical drug development. Spectroscopic studies like EPR are ideally suited to follow the conformational dynamics of the receptor and changes upon ligand binding. We labeled specific cystein residues of the receptor with 3-(2-Iodoacetamido)-PROXYL spin label by replacing naturally occurring reactive cysteines and introducing a new single cysteine at selected sites.