SNARES AND NSF IN TARGETED MEMBRANE-FUSION

A major current issue in vesicle trafficking is whether NSF (N-ethylma leimide-sensitive-factor) and alpha-SNAP (alpha-soluble NSF attachment protein) are required prior to SNARE (SNAP receptor) complex formatio n to allow vesicle docking, or after docking at a step close to membra ne fusion. Recent studies of yeast vacuolar fusion indicated that the requirement for ATP, NSF and a-SNAP could be completely satisfied prio r to SNARE docking complex assembly; however, the universality of a pr edocking role for these factors remains to be established. The vacuola r fusion system has also been used to directly demonstrate a requireme nt for SNARE proteins on both fusing membranes, verifying a central po stulate of current fusion models.