title: High-contrast imaging of fluorescent protein FRET by fluorescence polarization microscopy.
abstract: Detection of Forster resonance energy transfer (FRET) between fluorescent protein labeled targets is a valuable strategy for measurement of protein-protein interactions and other intracellular processes. Despite the utility of FRET, widespread application of this technique to biological problems and high-throughput screening has been limited by low-contrast measurement strategies that rely on the detection of sensitized emission or photodestruction of the sample. Here we report a FRET detection strategy based on detecting depolarized sensitized emission. In the absence of FRET, we show that fluorescence emission from a donor fluorescent protein is highly polarized. Depolarization of fluorescence emission is observed only in the presence of energy transfer. A simple detection strategy was adapted for fluorescence microscopy using both laser scanning and wide-field approaches. This approach is able to distinguish FRET between linked and unlinked Cerulean and Venus fluorescent proteins in living cells with a larger dynamic range than other approaches.
authors.forename: Megan A
authors.initials: MA
authors.lastname: Rizzo
authors.forename: David W
authors.initials: DW
authors.lastname: Piston
mesh_terms: D000818:Animals; D001426:Bacterial Proteins; D019556:COS Cells; D002522:Chlorocebus aethiops; D005454:Fluorescence Polarization / Q000379:methods*; D031541:Fluorescence Resonance Energy Transfer / Q000379:methods*; D049452:Green Fluorescent Proteins; D007089:Image Enhancement / Q000379:methods*; D008164:Luminescent Proteins; D018613:Microscopy, Confocal / Q000379:methods*; D008856:Microscopy, Fluorescence / Q000379:methods*; D008859:Microscopy, Polarization / Q000379:methods*; D025941:Protein Interaction Mapping / Q000379:methods*; D011994:Recombinant Proteins / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; C485182:Cyan Fluorescent Protein; D008164:Luminescent Proteins; D011994:Recombinant Proteins; C054562:yellow fluorescent protein, Bacteria; D049452:Green Fluorescent Proteins