GqPCR-mediated signalling in the spotlight: from visualization towards dissection and quantification

Signals relayed through G protein-coupled receptors (GPCR) play pivotal roles in human physiology and are important drug targets. About 40% of all GPCRs couple to the heterotrimeric G protein Gq. Biochemical studies as well as crystallography have improved our understanding of GqPCRs and their downstream partners. Here we focus on the "functional imaging" tools that have been developed to visualize, dissect and quantify signalling processes at the single living cell level. We provide an overview of the most important developments in readout of signalling by FRET and BRET, as well as of the labelling strategies commonly used to visualize proteins in living cells. In addition, tools that allow manipulation of individual steps, including chemically inducible dimerization and optogenetic tools are covered. Together, these developments will provide unprecedented insights in GqPCR signalling in living cells and model organisms.