Location-biased β-arrestin conformations direct GPCR signaling
{beta}-arrestins are multifunctional intracellular proteins that regulate the desensitization, internalization and signaling of over 800 different G protein-coupled receptors (GPCRs) and interact with a diverse array of cellular partners1,2. Beyond the plasma membrane, GPCRs can initiate unique signaling cascades from various subcellular locations, a phenomenon known as "location bias"3,4. Here, we investigate how {beta}-arrestins direct location-biased signaling of the angiotensin II type I receptor (AT1R). Using novel bioluminescence resonance energy transfer (BRET) conformational biosensors and extracellular signal-regulated kinase (ERK) activity reporters, we reveal that in response to the endogenous agonist Angiotensin II and the {beta}-arrestin-biased agonist TRV023, {beta}-arrestin 1 and {beta}-arrestin 2 adopt distinct conformations across different subcellular locations, which are intricately linked to differential ERK activation profiles. We also uncover a population of receptor-free catalytically activated {beta}-arrestins in the plasma membrane that exhibits insensitivity to different agonists and promotes ERK activation on the plasma membrane independent of G proteins. These findings deepen our understanding of GPCR signaling complexity and also highlight the nuanced roles of {beta}-arrestins beyond traditional G protein pathways.