CHAPTER 4:Molecular Biology Techniques Applied to GPCR Allosteric and Biased Ligands

G-protein-coupled receptors (GPCRs) have proven to be highly successful therapeutic targets, representing more than 40% of the top 200 worldwide best-selling drugs, and are projected to represent 120 billion US dollars of revenues per year by 2017. Interestingly, these marketed compounds modulate the activity of a restricted set of 100 GPCRs out of the 350 that are considered to be potential drug targets, indicating that in spite of the powerful drug discovery arsenal that is now available, it remains hard to “crack” new GPCRs. This is probably due to the inherent complexity of GPCR signaling, that arises from the multiplicity of intracellular pathways that can be elicited by a single receptor, according to the downstream effectors it is interacting with. To overcome these obstacles, an interesting strategy has emerged targeting allosteric modulator (AM) sites. This chapter reviews current technologies used for AM high-throughput screening (HTS) and signaling characterization, as well as the utility of combining novel approaches to efficiently discover and characterize their ability to activate or inhibit specific signaling pathways.