Chemical biology approaches to resolve the subcellular GPCR signaling landscape.

G-protein-coupled receptors (GPCRs) are the largest class of membrane receptors and key drug targets. Over the past decade, extensive evidence has shown that GPCRs signal from various intracellular compartments to generate distinct cellular and physiological responses. Therefore, it is critical to understand how the subcellular sites of GPCR signaling affect receptor function and pharmacology, and how the insights can be exploited to develop improved therapeutics. This Review highlights recent advances in GPCR signaling and spatiotemporal regulation with a focus on chemical biology approaches. We discuss biosensors for real-time recordings of localized GPCR responses, tools for site-selective tuning of signaling pathways, quantitative approaches to determine interactors and global cellular behaviors, reporters enabling unbiased mechanistic screening and compartment-specific ligands. We emphasize the need to develop and advance chemical biology tools to deepen our mechanistic understanding of compartmentalized GPCR signaling and fuel future drug discovery efforts.