Fig. 3. Exocytosis of internalized MPR300 in control (ct) and µ1A-deficient cells (µ1A–/–). (A) Cells were biotinylated on ice, warmed to 37°C for 2 minutes, cooled on ice and subjected to biotin stripping. The fraction of the internal biotinylated receptors is set to 100% (t). Parallel cultures were subjected to up to three additional cycles of warming to 37°C for two minutes, cooling on ice and biotin stripping. Numbers below give the signal intensities for biotinylated MPR300 as a percentage of the total. (B) Kinetics of exocytosis for biotinylated MPR300, see (A). Numbers correspond to the decrease in intracellular biotinylated receptors. Closed circles and solid line; control cells, open circles; and dashed line, µ1A-deficient cells. Data are from three independent experiments.
