fluorescence technology luminiscence technology complemented donor-acceptor resonance energy transfer MI:2171 PSI-MI bret complementation assay copa-ret ppm This technology is based on quantifying the BRET between a pair of participants bearing complementation tags and a participant tagged with a bioluminescent enzyme or a fluorescent tag. The tags held by the pair of participants are complementary halves of either a fluorescent tag (N- and C- fragments of the Venus fluorescent protein, for example) or a bioluminescent enzyme (N- and C- fragments of Renilla luciferase, for example). Interaction between the pair of participants leads to reconstruction of the bioluminescent enzyme/fluorescent protein, which can then emit/accept photons that are accepted/emitted by the tag in the third participant, generating the signal used to detect the interaction. The signals emitted by the bioluminescent enzyme and the fluorescent tag have different wavelengths, so they can be distinguished. bret complementation 2015-04-29T13:25:55Z