biostudies-literatureFelce JHMedical Research CouncilWellcome TrustL41-3https://www.ebi.ac.uk/biostudies/studies/S-EPMC4070276biostudies-literatureUnknown106(12)We show that in conventional, competition-based bioluminescence resonance energy transfer (BRET) assays of membrane protein stoichiometry, the presence of competitors can alter tagged-protein density and artifactually reduce energy transfer efficiency. A well-characterized monomeric type I membrane protein, CD86, and two G protein-coupled receptors β2AR and mCannR2, all of which behave as dimers in these conventional assays, exhibit monomeric behavior in an improved competition-based type-3 BRET assay designed to circumvent such artifacts.Biophysical journalType-3 BRET, an improved competition-based bioluminescence resonance energy transfer assay.PMC4070276098274G0901545Davis SJKnox RGFelce JHfalseType-3 BRET, an improved competition-based bioluminescence resonance energy transfer assay.We show that in conventional, competition-based bioluminescence resonance energy transfer (BRET) assays of membrane protein stoichiometry, the presence of competitors can alter tagged-protein density and artifactually reduce energy transfer efficiency. A well-characterized monomeric type I membrane protein, CD86, and two G protein-coupled receptors β2AR and mCannR2, all of which behave as dimers in these conventional assays, exhibit monomeric behavior in an improved competition-based type-3 BRET assay designed to circumvent such artifacts.2014-01-01T00:00:00Z2014 Jun2025-04-18T21:25:33.186Z2019-03-27T01:30:49ZS-EPMC40702762494079110.1016/j.bpj.2014.04.061