Figure 1. Potential pharmacologic mechanisms of biased G protein-coupled receptor signaling.

Multiple potential classes of biased pharmacologic compounds targeting GPCRs have been identified. These range from orthosteric ligands that interact with the binding site of the endogenous ligand, to allosteric modulators that bind a receptor at a site distinct from the endogenous ligand, to bitopic ligands that bind at both orthosteric and allosteric sites.