ABSTRACT
The ß3-adrenergic receptor (ß3AR) is the most essential drug target for overactive bladder and has therapeutic potentials for the treatments of type 2 diabetes and obesity. Here, we report the cryo-electron microscopy structures of the ß3AR-Gs signaling complexes with the selective agonist, solabegron and the nonselective agonist, isoproterenol. Comparison of the isoproterenol-, mirabegron-, and solabegron-bound ß3AR structures revealed that the extracellular loop 2 changes its conformation depending on the bound agonist and plays an essential role in solabegron binding. Moreover, ß3AR has an intrinsically narrow exosite, regardless of the agonist type. This structural feature clearly explains why ß3AR prefers mirabegron and solabegron, as the narrow exosite is suitable for binding with agonists with elongated shapes. Our study deepens the understanding of the binding characteristics of ß3AR agonists and may pave the way for developing ß3AR-selective drugs.