Figure 7: Dynamic complex stabilization by the actin cytoskeleton.

(a) Co-trajectory length of RGA-induced ternary complexes is dramatically decreased due to disruption of the actin cytoskeleton by LatB (Latrunculin B) treatment. Data are based on n>60 (−LatB) and n>17 (+LatB) cells. Co-trajectories with less than 30 frames were not considered. (b) Diffusion constants of fluorescent ligand-bound receptors in absence and in presence of LatB (mean±s.d. of n>10 cells). (c) Maximum relative pSTAT6 level in presence of LatB is distinctly lowered for RGA. HeLa cells were treated with 10 μm LatB, stimulated for 15 min with saturating doses of the respective ligand and the relative levels of pSTAT6 compared to untreated cells were analysed by phospho-flow cytometry using anti-pSTAT6 specific antibodies coupled to fluorescent dyes. Error bars correspond to the s.d. from three independent experiments. Statistical analysis by Student’s t-test (*P<0.05). (d) ^DY647IL-4Rα (green) and ^TMRIL-13Rα1 (magenta) complex re-association at single molecule level in presence of RGA. Images showing the complex at different time points of a 330-frame (10.6 s) time-lapse experiment (cf. Supplementary Movie 4) including its corresponding co-trajectory (white). Scale bar: 1 μm. (e) Distance between the two molecules throughout the entire trajectory.