Supplementary Movie 2

Partial relocation of SNAP-23 to internal membranes during mast cell exocytosis. IgE sensitized transfected RBL cells expressing GFP SNAP-23 were stained with Lysotracker. Real time imaging of SNAP-23 movements were captured during mock stimulation (Movie 1) and allergen stimulation (Movie 2). Movies were captured starting at 2 min after the addition of medium alone or allergen, DNP-BSA. Total 300 frames were taken. Display rate is 14 frames per second. (Movie 1) Shows that during mock stimulation SNAP-23 remains associated with plasma membrane and there is not much movements of lysotracker towards plasma membrane. Representative Movie 2 (of 18 captured movies) shows, upon receptor cross linking of RBL mast cells showing that SNAP-23 relocates to internal granule membranes that are undergoing homotypic fusion and compound exocytosis. Red Lysotracker containing granules surrounded by green GFP-SNAP-23WT can also be visualized during the course of acquisition.