Human muscarinic receptor M 2 is one of the five subtypes of muscarinic receptors belonging to the family of G-protein-coupled receptors. Muscarinic receptors are targets for multiple neurodegenerative diseases. The challenge has been designing subtype-selective ligands against one of the five muscarinic receptors ...
Human muscarinic receptor M 2 is one of the five subtypes of muscarinic receptors belonging to the family of G-protein-coupled receptors. Muscarinic receptors are targets for multiple neurodegenerative diseases. The challenge has been designing subtype-selective ligands against one of the five muscarinic receptors. We report high-resolution structures of a thermostabilized mutant M 2 receptor bound to a subtype-selective antagonist AF-DX 384 and a nonselective antagonist NMS. The thermostabilizing mutation S110R in M 2 was predicted using a theoretical strategy previously developed in our group. Comparison of the crystal structures and pharmacological properties of the M 2 receptor shows that the Arg in the S110R mutant mimics the stabilizing role of the sodium cation, which is known to allosterically stabilize inactive state(s) of class A GPCRs. Molecular dynamics simulations reveal that tightening of the ligand-residue contacts in M 2 receptors compared to M 3 receptors leads to subtype selectivity of AF-DX 384.
Organizational Affiliation: 
Japan Science and Technology Agency (JST) and Japan Agency for Medical Research and Development (AMED), Core Research for Evolutional Science and Technology (CREST), Konoe-cho, Yoshida, Sakyo-ku, Kyoto, Japan. kobayashi.takuya.4r@kyoto-u.ac.jp.