Figure 3. Mathematical model of p-EGFR predicts signalling amplitude and duration depends on early endosome fusion/fission rate.
Parameters of the mathematical model were fitted to the experimentally measured number of p-EGFR endosomes, total integral intensity of p-EGFR, mean integral intensities of p-EGFR per endosome and total vesicular EGFR. The experimental data were obtained in a time course of EGF stimulation at four concentrations (0.5, 1.0, 5.0, and 10 ng/ml, colour coded as indicated). The fit results are presented on panels (A–C). The experimental data and model predictions are drawn as filled circles and solid curves, respectively. (A) Number of p-EGFR endosomes per 1000 μm2 of cell area. (B) Total integral intensity of p-EGFR measured by FRET. The scaling factors that convert arbitrary numbers of the model to the experimental data were found by the least square procedure (see ‘Materials and methods’). (C) Comparison of mean integral intensity of p-EGFR per endosome measured experimentally (filled circles) and mathematical model (solid curves) of the time course of p-EGFR upon EGF stimulation as in Figure 1A. The concentration of EGF is colour coded as presented. (D) Model predictions of the total amount of p-EGFR in endosomes as a function of EGF concentration and in the presence of different homotypic early endosome fusion rates (colour coded as indicated).
Figure 3—figure supplement 1. A mathematical model without the non-linear phosphorylation dependency cannot describe the mean amount of p-EGFR per endosome.
