Figure 4.

SNARE assembly and disassembly mediate the fusion of MVBs with the cell membrane. One v-SNARE located on the vesicle membrane and three t-SNAREs located on the target membrane are tightly tethered to each other as they approach and assemble into a stable, four-stranded helical bundle transmembrane complex. This further brings the two membranes into contact and promotes fusion, thus releasing the particles in the MVBs from the cells. After this step is complete, the SNARE complex remains on the fused target membrane and is disassembled into monomeric proteins. In addition, the v-SNARE only continues to function after it is recycled to the vesicle membrane.