Time-Lapse Förster Resonance Energy Transfer Imaging by Confocal Laser Scanning Microscopy for Analyzing Dynamic Molecular Interactions in the Plasma Membrane of B Cells.

For decades, various Förster resonance energy transfer (FRET) techniques have been developed to measure the distance between interacting molecules. FRET imaging by the sensitized acceptor emission method has been widely applied to study the dynamical association between two molecules at a nanometer scale in live cells. Here, we provide a detailed protocol for FRET imaging by sensitized emission using a confocal laser scanning microscope to analyze the interaction of the B cell receptor (BCR) with the Lyn-enriched lipid microdomain on the plasma membrane of live cells upon antigen binding, one of the earliest signaling events in BCR-mediated B cell activation.