The genetic architecture of G-protein coupled receptor signaling

G-protein coupled receptors (GPCRs) are the most abundant class of human receptors and drug targets. The vast majority of GPCR drugs bind the conserved orthosteric pocket, which can lead to non-specificity and toxicity. Precision modalities such as biased signaling and allosteric modulation could lead to GPCR therapeutics with improved efficacy and safety profiles. The rational design of precision therapies is, however, limited by the lack of high-resolution functional understanding of GPCRs. Here we present a general approach to chart high-resolution functional maps of GPCRs and apply the approach to the β2 adrenergic receptor. Across ∼150,000 measurements of five different phenotypes, we construct an unprecedented picture of signaling properties of this model receptor. A contiguous core activation network of residues required for signaling links the ligand binding site to the transducer binding site. Residues controlling signaling parameters connect to this core network, with determinants of signaling bias located more peripherally. Dose-response curves for nearly all possible amino acid substitutions, a total of >7,500 different proteins, reveal the relationship between expression level and potency; and the spatial distribution of potency changing residues. The multi-modal maps rationalize previous serendipitously discovered allosteric sites and prospectively annotate novel sites to target. Application of this approach across the superfamily of GPCRs will unlock deep understanding of these critical molecules and enable rational design of precision GPCR therapeutics.