Figure 3: Mathematical model of Megalin endosomal itinerary in subconfluent MDCK cells.

(a) Representative time-lapse confocal sections from 2D movies of subconfluent MDCK cells co-transfected with mMeg-HA and the SE marker Rab4-GFP (top), the RE markers TfR-GFP (middle) or Rab11-mCherry (bottom). Pre-bound 647-MαHA (45 min at 4 °C) was allowed to internalize (45 min at 37 °C) during live-imaging acquisition. (b) Co-localization time course for each endosomal marker with internalized 647-MαHA. Curves represent average and s.e. values from six movies per condition. (c) Cartoon displaying all endosomal compartments of subconfluent mMeg-MDCK cells and the constant coefficients (k₀₁, k₁₀, k_12, k₂₀, k₂₃ and k₃₀) denoting the transfer rates for sequential movement of Megalin through these compartments. (d) Constant coefficients values (k) of the model. (e) Kinetics of Megalin pixels colocalizing with SE^Rab4, RE^TfR and RE^Rab11 for the experimental replicas (continuous curves), experimental averages (dots) and CI₉₅ model prediction (shaded areas). (f) Unidirectional Megalin fluxes (J_ij) across the PM, SE^Rab4, RE^TfR and RE^Rab11. Scale bar, 10 μm.