Fig. 4.
Two-photon FRAP experiments at mature adherens junctions of MCF7-E-cadherin-GFP cells. (A) Typical image of MCF7 cells stably expressing E-cadhering GFP. (B) Profile analysis of fluorescence recovery. 17 fluorescence profile mean curves before bleaching (red circle) and at 0.6 s (blue square), 15 s (green diamond), 45 s (black x), 105 s (pink +), and 195 s (cyan triangle) after photobleaching are shown. All postbleach curves are fit by Gaussian models (dashed lines). (C) The widths of the gaussians at different times after photobleaching are compared with the reference width after photobleaching in fixed cells. The error bars are larger than for MDCK cells (Fig. 2) due to a decreased signal/noise ratio in MCF7 cells. (D) The recovery curve (red circle, n = 25) is well fit by a first-order exchange model with koff = 0.0021 ± 0.05 s−1. (Upper Left Inset) Linear time axis representation. Photobleaching spots of 0.5 (n = 25, red circle), 0.8 (n = 16, blue triangle) and 1.2 (n = 15, green square) μm width along the junction axis are fitted by first-order exchange with similar coefficients: koff = 0.021 ± 0.005, 0.018 ± 0.005 and 0.015 ± 0.005 s−1 respectively.