TY - JOUR T1 - A New Molecular Mechanism To Engineer Protean Agonism at a G Protein–Coupled Receptor JF - Molecular Pharmacology JO - Mol Pharmacol SP - 348 LP - 356 DO - 10.1124/mol.116.107276 VL - 91 IS - 4 AU - Anna De Min AU - Carlo Matera AU - Andreas Bock AU - Janine Holze AU - Jessica Kloeckner AU - Mathias Muth AU - Christian Traenkle AU - Marco De Amici AU - Terry Kenakin AU - Ulrike Holzgrabe AU - Clelia Dallanoce AU - Evi Kostenis AU - Klaus Mohr AU - Ramona Schrage Y1 - 2017/04/01 UR - http://molpharm.aspetjournals.org/content/91/4/348.abstract N2 - Protean agonists are of great pharmacological interest as their behavior may change in magnitude and direction depending on the constitutive activity of a receptor. Yet, this intriguing phenomenon has been poorly described and understood, due to the lack of stable experimental systems and design strategies. In this study, we overcome both limitations: First, we demonstrate that modulation of the ionic strength in a defined experimental set-up allows for analysis of G protein–coupled receptor activation in the absence and presence of a specific amount of spontaneous receptor activity using the muscarinic M2 acetylcholine receptor as a model. Second, we employ this assay system to show that a dualsteric design principle, that is, molecular probes, carrying two pharmacophores to simultaneously adopt orthosteric and allosteric topography within a G protein–coupled receptor, may represent a novel approach to achieve protean agonism. We pinpoint three molecular requirements within dualsteric compounds that elicit protean agonism at the muscarinic M2 acetylcholine receptor. Using radioligand-binding and functional assays, we posit that dynamic ligand binding may be the mechanism underlying protean agonism of dualsteric ligands. Our findings provide both new mechanistic insights into the still enigmatic phenomenon of protean agonism and a rationale for the design of such compounds for a G protein–coupled receptor. ER -