Figure 2.

Comparison of the time course of plasma membrane translocation of Cys1–GFP in response to activation of IgE or PAF receptors. (A) Sequential images of RBL cells expressing Cys1–GFP taken immediately before and 40, 80, and 200 s after cross-linking of the IgE receptors with 20 μg/ml DNP-BSA. The images shown were not corrected for photobleaching. (B) For each cell in a given image, a line intensity profile across the cell was obtained. Typical intensity profiles are shown at each of the four time points. (C) Schematic representation of the method used to calculate a relative increase in plasma membrane staining. A relative increase in plasma membrane localization was calculated from the plasma membrane [I _mb] and the average cytosolic fluorescence intensity [I _cyt], respectively. (D) The plasma membrane translocation was represented as a relative increase in plasma membrane localization [R] and plotted as a function of time. The antigen or the PAF ligand were added at t = 0 s. The resulting curves represent the time course of plasma membrane translocation of Cys1–GFP in response to IgE receptor cross-linking and PAF receptor activation, respectively.