Abstract Previously, we demonstrated the involvement of Asn293 in helix VI of the human β 2-adrenergic receptor in stereoselective agonist recognition and activation. In the present study, we have further explored the role of this residue by synthesizing derivatives of isoproterenol and clenbuterol, two β-adrenergic receptor agonists. We analyzed their efficacy and affinity on the wild-type and a mutant receptor (Asn293Leu). Each compound ...