Supplemental Material

This article contains the following supporting material:

• Movie 1 - Fusion of a MATa cell expressing cytoplasmic GFP with a MATα cell expressing cytoplasmic DsRed. Images were collected at 5-second interval for 145 seconds.

• Movie 2 - Vacuoles stream into the emerging bud before they fuse. MATa GFP cells were pulse labeled with FM4-64 and then mated to MATα cells that had been labeled with CellTracker Blue. GFP (green) and FM4-64 (white) images were collected at 30-second intervals for 150 minutes. CellTracker Blue images (not shown) were collected at 10-minute intervals to reduce photobleaching. Plasma membrane fusion is marked by GFP transfer to MATα cells. FM4-64 labeled vacuole membranes remain in the MATa lobe of the zygote until after bud emergence. Less than 15% of the total FM4-64 enters the MATα vacuoles by vesicle transport. Vacuoles stream into the bud, and then fuse with vacuoles arising from the MATα cell. The mating pairs shown in Figure 1e are at the upper left corner.

• Figure 1 - Fusion pore permeance of 109 wild-type fusion pores from 7 independent experiments. (A) A scatter plot presenting all 109 pores. (B) Histograms presenting the distribution of initial permeances and rates of permeance increase.

• Figure 2 - Mating and cell wall remodeling defects of cell fusion mutants. MATa and MATα DsRed cells were mated on SC plates for 1.5 hours. (A) Cytoplasmic mixing was scored by monitoring DsRed transfer. (B) Cell wall remnants were detected by DIC microscopy (n>100).