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Updated: Jan 10, 2026

A Kinetic Fluorescence-based Ca2+ Mobilization Assay to Identify G Protein-coupled Receptor Agonists, Antagonists, and Allosteric Modulators
Published on: February 20, 2018
Class A and B GPCRs trigger rapid Gαs translocation to late and slow recycling endosomes
Andréanne Laniel1, Brian Holleran1, Émy Labonté1
1Institut de Pharmacologie de Sherbrooke, Department of Pharmacology and Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec, QC, Canada.
Abstract:
Gαs is classically known for mediating G protein-coupled receptor (GPCR) signaling at the plasma membrane (PM), but it is now established that Gαs also supports a second wave of signaling from internalized GPCRs within early endosomes. However, the mechanisms underlying Gαs trafficking remain unclear. Here, using live-cell confocal microscopy and bioluminescence resonance energy transfer (BRET) assays, we investigated Gαs-GFP dynamics following activation of class A (β2AR) and class B (V2R) receptors, which exhibit different level of endosomal signaling. Our findings demonstrate that Gαs rapidly ( < 2 min) translocates to late (Rab7) and slow recycling (Rab11) endosomes, bypassing the classical endocytic route and displaying only transient colocalization with receptors. This trafficking depends on Gαs activation at the PM, its release from the membrane, and an intact palmitoylation site, but occurs independently of receptor internalization. This work shed light on non-canonical route for Gαs endosomal trafficking, with important implications for endosomal GPCR signaling.
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