A GPCR-G protein-β-arrestin megacomplex enabled by a versatile allosteric modulator.

Approximately one-third of clinical drugs mediate their therapeutic effects through G protein-coupled receptors (GPCRs), highlighting their immense therapeutic relevance. Novel approaches to modulate GPCR activity have the potential to yield unique pharmacological profiles. Conventionally, the G protein and β-arrestin signaling pathways downstream of GPCRs have been viewed as mutually exclusive. Using the in-house developed survival pressure selection (SPS) method, a high-throughput platform for GPCR agonist discovery, we identified an allosteric ligand that stabilizes a GPCR-G protein-β-arrestin megacomplex, thereby mediating sustained receptor signaling following internalization. Remarkably, this compound, atazanavir, exhibits pan-receptor activation across multiple family A GPCRs, including GPR119, β1AR, and β2AR, demonstrating the broad applicability of this regulatory mechanism. This discovery uncovers a distinct mechanism of GPCR regulation, opening alternative avenues for the development of therapeutics targeting GPCRs.