Table 1.

| Comparison of the SUV-SBL and the tethered-vesicle fusion assays

SUV-SBL assay	Tethered-vesicle assay
Better mimics the geometry found in the fusion of small organelles with large, flat target membranes, as in synaptic vesicle-plasma membrane fusion	Better mimics the geometry of homotypic fusion, e.g. of endosomes.
t-SNARE densities can be reduced to << 1 per SUV to avoid aggregation	At least a few SNAREs/liposome must be used
Difficult to increase t-SNARE densities to >1 per SUV	High t-SNARE densities are easily achievable
Better suited for real-time monitoring of docking and fusion events, since the fusion rate per unit area is high even using pM SUV concentrations and it takes hours to consume the t-SNAREs on the surface. This is because the v-SUVs react with a very large surface area.	The area fraction occupied by the acceptor SUVs on the coverslip surface is tiny. Thus, at the same bulk SUV density, the docking and fusion rates are very low compared to the SUV-SBL assay. The number of fusions that can be cumulated is limited by the low density of acceptor SUVs (a few hundred per viewfield).
Fusion end-products are not visible.	Fusion end-products are visible and accumulate over time. Thus the assay is well-suited for blind incubation (~hour timescale), followed by imaging of the end-products.