Crosslinking Photosensitized by a Ruthenium Chelate as a Tool for Labeling and Topographical Studies of G-Protein-Coupled Receptors Original Research Article

The purpose was to apply oxidative crosslinking reactions to the study of recognition and signaling mechanisms associated to G-protein-coupled receptors. Using a ruthenium chelate, Ru(bipy)32+, as photosensitizer and visible light irradiation, in the presence of ammonium persulfate, we performed fast and efficient covalent labeling of the B2 bradykinin receptor by agonist or antagonist ligands possessing a radio-iodinated phenol moiety. The chemical and topographical specificities of these crosslinking experiments were investigated. The strategy could also be applied to the covalent labeling of the B1 bradykinin receptor, the AT1 angiotensin II receptor, the V1a vasopressin receptor and the oxytocin receptor. Interestingly, we demonstrated the possibility to covalently label the AT1 and B2 receptors with functionalized ligands. The potential applications of metal-chelate chemistry to receptor structural and signaling studies through intramolecular or intermolecular crosslinking are presented.