Publication — IRIC

Michaelis-Menten Quantification of Ligand Signaling Bias Applied to the Promiscuous Vasopressin V2 Receptor.

Activation of G protein-coupled receptors by agonists may result in the activation of one or more G proteins and recruitment of arrestins. The extent of the activation of each of these pathways depends on the intrinsic efficacy of the ligand. Quantification of intrinsic efficacy relative to a reference compound is essential for the development of novel compounds. In the operational model, changes in efficacy can be compensated by changes in the “functional” affinity, resulting in poorly defined values. To separate the effects of ligand affinity from the intrinsic activity of the receptor, we developed a Michaelis-Menten based quantification of G protein activation bias that uses experimentally measured ligand affinities and provides a single measure of ligand efficacy. We used it to evaluate the signaling of a promiscuous model receptor, the Vasopressin V2 receptor (V2R). Using BRET-based biosensors, we show that the V2R engages many different G proteins across all G protein subfamilies in response to its primary endogenous agonist, arginine vasopressin, including Gs and members of the Gi/o and G12/13 families. These signaling pathways are also activated by the synthetic peptide desmopressin, oxytocin, and the nonmammalian hormone vasotocin. We compared bias quantification using the operational model with Michaelis-Menten based quantification; the latter accurately quantified ligand efficacies despite large difference in ligand affinities. Together, these results showed that the V2R is promiscuous in its ability to engage several G proteins and that its’ signaling profile is biased by small structural changes in the ligand. SIGNIFICANCE STATEMENT: By modelling the G protein activation as Michaelis-Menten reaction, we developed a novel way of quantifying signalling bias. V2R activates, or at least engages, G proteins from all G protein subfamilies, including Gi2, Gz, Gq, G12, and G13. Their relative activation may explain its Gs-independent signalling.

Publication date
September 1, 2022
Principal Investigators
Heydenreich FM, Plouffe B, Rizk A, Milić D, Zhou J, Breton B, Le Gouill C, Inoue A, Bouvier M, Veprintsev DB
PubMed reference
Mol Pharmacol 2022;102(3):139-149
PubMed ID
Laboratory of Biomolecular Research, Villigen, Switzerland (F.M.H., A.R., D.M., D.B.V.); Department of Biology, Paul Scherrer Institute, Zürich, Switzerland (F.M.H., A.R., D.M., D.B.V.); Department of Biochemistry and Molecular Medicine, Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, Québec, Canada (F.M.H., B.P., J.Z., B.B., C.L., M.B.); MRC Laboratory of Molecular Biology, Cambridge, United Kingdom (F.M.H.); The Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen’s University Belfast, Belfast, United Kingdom (B.P.); Department of Structural and Computational Biology, Max Perutz Laboratories, University of Vienna, Vienna, Austria (D.M.); Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan (A.I.); Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, Midlands, United Kingdom (D.B.V.); and Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, United Kingdom (D.B.V.)