Fig. 17.

a Superposition of PAM LY2119620 bound to M2 receptor (pink cartoon, pink sticks; PDB: 4MQT) and M4 receptor (yellow cartoon, yellow sticks; PDB: 7V68). b Detailed binding modes of M2 receptor bound to LY2119620. c Detailed binding modes of M4 receptor bound to LY2119620. Hydrogen bonds are presented as orange dashes and π–π stacking is presented as gray dashes. d Superimposed views of highlighted residue Trp422^7.36 on M2 receptor–iperoxo–LY2119620 (pink cartoon, pink sticks; PDB: 6U1N), M2 receptor–LY2119620 (purple cartoon, purple sticks; PDB: 4MQT), and M2 receptor–iperoxo (blue cartoon, blue sticks; PDB: 4MQS) structures. The orthosteric agonist iperoxo is presented in orange