Figure 3. Cell fusion by VAMPs and plasma membrane t-SNAREs.

24 h after transfection, v-cells that expressed tTA and VAMPs 1, 2, 3, 4, 5, 7 or 8 were combined with t-cells that expressed TRE-LacZ and (A) syntaxin1/SNAP-25 or (B) syntaxin4/SNAP-25. After 24 h, cell fusion was quantified using the enzymatic cell fusion assay. Control cells (-VAMP) were cotransfected with the empty vector and the plasmid encoding tTA. Only baseline β-galactosidase activity was detected when the control cells were incubated with the t-cells. The flipped SNARE plasmids were transfected at the same concentration. Error bars represent standard deviation of three independent experiments. * P<0.05 vs. VAMP1.