Supplemental Material

This article contains the following supporting material:

• Movie 1 - Exocytosis of TIV-pHL vesicles and tubules A Cos7 cell transfected with TIV-pHL was imaged at 30 images/min with an exposure time of 400ms per frame for a total of 9min 42sec. Numerous circular puffs of light appear for a few seconds each. Several worm-like structures corresponding to the fusion of tubules are also seen (at 4min 06sec, for instance).

• Movie 2 - The exocytosis of TI-VAMP is positively regulated by Cdc42 Cos7 cells were cotransfected with TIV-pHL and RFP (left cell) or with Cdc42V12-RFP (right cell) and imaged for 6 min. 18sec. There is a high increase in the number of exocytic events in the cell coexpressing TIV-pHL and Cdc42V12-RFP compared to the cell coexpressing TIV-pHL and RFP.

• Movie 3 - The stimulatory effect of Cdc42-V12-RFP on exocytosis is F-actin-dependent A Cos7 cell cotransfected with Cdc42V12-RFP and TIV-pHL was imaged before (left) and 15min. after treatment with 5µM cytochalasin B (right) for 6min 26 sec each. Cytochalasin B strongly inhibits the number of exocytic events (compare exocytic activity in the right panel with the left panel).