(A) HeLa cells were transfected with EGFP–U1 70K and cotransfected with either mCherry-C1 or mCherry-SF2/ASF

Shown are confocal images of transfected cells and FLIM images of the same cells, in which mean fluorescence lifetime is shown in pseudocolor. The color scale with the respective lifetimes (in picoseconds [ps]) is indicated. The percentage of FRET efficiencies and FRET amplitude are shown in continuous pseudocolor. The color scale with the respective FRET efficiencies (percentage) is indicated. The FRET amplitude % represents the fraction of interacting donor molecules, also defined as the FRET population % (or concentration of FRET species). (B) FRET between U1 70K and SF2/ASF, in the presence of DRB, measured by FLIM. Experiments were performed exactly as described for A, except cells were treated with 25 μg/ml of DRB for 2 h before images were taken. Bars, 10 μm. (C) FRET efficiencies calculated from FLIM measurements for the interaction of SF2/ASF with U1 70K in the presence and absence of DRB. Plot is of mean FRET efficiencies ± SD for 9–20 cells. To measure the FRET efficiency in the speckles and nucleoplasm, a region characteristic of each was selected for each cell. P-values were obtained as described in the legend. *, P < 0.1.<p><b>Copyright information:</b></p><p>Taken from "Spatial mapping of splicing factor complexes involved in exon and intron definition"</p><p></p><p>The Journal of Cell Biology 2008;181(6):921-934.</p><p>Published online 16 Jun 2008</p><p>PMCID:PMC2426932.</p><p>