Exploring functional consequences of GPCR oligomerization requires a different lens.

ABSTRACT

As the largest family of cell surface receptors, G protein-coupled receptors (GPCRs) represent an important strategic class of therapeutic targets. Attaining a clearer perspective of how such signaling complexes set molecular events in motion could have significant impact on our understanding and treatment of human diseases. As such, many experimental approaches have set out to better understand signaling networks associated with individual receptors to understand signaling architectures and their relationship to signaling outcomes. However, designing in vitro assays aimed at addressing signaling events downstream of single GPCRs must also take into account their propensity to form homo- and heterooligomeric complexes. In the context of GPCR oligomers, physical interactions with a partner protein can have a number of potential consequences, which we will explore in this review. We will also discuss methods used to identify putative dimer partners as well as the various techniques used to study the functional consequences of such complex formation. Since the full functional significance and physiological relevance of GPCR oligomers remains incompletely understood, owing in part to technical limitations, new tools to elucidate molecular mechanisms underlying allosteric co-regulation occurring between two GPCRs are required. Accordingly, using the example of the FP/AT1R heterodimer, we discuss the potential of the FlAsH-BRET approach as a simple tool to reveal how allosteric information is transmitted via conformational rearrangements within putative GPCR complexes and as a means to deorphanize receptors.