Figure 4

SYP4 family members and VTI11 can function together in membrane fusion. A-C. Purified SYP41 (A), SYP42 (B) or SYP43 (C) were incorporated into acceptor vesicles, and VTI11, VTI12 or MEMB11 were reconstituted into donor vesicles. Mixing of acceptor vesicles and donor vesicles was measured as in Figure 3. The change in NBD fluorescence was monitored after mixing each R-SYP4 family and R-VTI11 either in the presence (black line) or absence of YKT62 (green line) and mixing each R-SYP4 family and either R-MEMB11 (yellow line) or R-VTI12 (red line) in the presence of YKT62. D. Maximum percentages of fusion of donor vesicles containing R-VTI11, R-VTI12 or R-MEMB11 with vesicles reconstituted with a SYP4 family protein were analyzed statistically and compared. Maximum percentage of fusion between R-SYP42 and either R-VTI11 or R-VTI12 showed a significant difference by t-test (p = 0.006, labeled with asterisk). Error bars represent standard deviation (n = 7).