Bioluminescence Resonance Energy Transfer (BRET)

Illumination-free resonance energy transfer from a luciferase-catalyzed bioluminescent donor to a fluorescent acceptor protein.

Specifications & Metrics

type: Biophysical & Biosensor
readout: Ratiometric emission of fluorescent acceptor to luciferase donor light output
measures: GPCR–G-protein coupling, β-arrestin recruitment, dimerization, and target engagement in live cells
format: 96- and 384-well luminescence microplate reader assays without external excitation light
pioneer: Adapted from Förster resonance transfer using Renilla reniformis luciferase and engineered NanoLuc donors

Unlike fluorescence-based FRET, BRET uses a luciferase enzyme (such as Renilla reniformis luciferase or engineered Oplophorus gracilirostris NanoLuc) oxidizing a luciferin substrate to excite the acceptor without external laser illumination.
Eliminating external excitation light avoids cellular autofluorescence, direct acceptor excitation, and fluorophore photobleaching, yielding higher signal-to-noise ratios in live-cell microplate screens.
In receptor pharmacology, BRET biosensors quantify biased agonism by measuring the relative potency and efficacy of a ligand for heterotrimeric G-protein dissociation versus β-arrestin recruitment at the same GPCR.