Determining allosteric modulator mechanism of action: Integration of radioligand binding and functional assay data

The drive to produce safer and more receptor subtype selective drugs has sparked a renewed interest in allosteric modulators of G protein-coupled receptors. The increasing use of functional assays has shown that allosteric ligands are capable of modulating both orthosteric agonist affinity and efficacy, as well as mediating receptor activation in their own right. Such a complex range of behaviours can be difficult to discern from single datasets; this chapter seeks to explain how to use radioligand binding and functional assay datasets in concert to elucidate allosteric modulator mechanism of action.