VAMP (synaptobrevin) is present in the plasma membrane of nerve terminals.

Synaptic vesicle docking and exocytosis require the specific interaction of synaptic vesicle proteins (such as VAMP/synaptobrevin) with presynaptic plasma membrane proteins (such as syntaxin and SNAP 25). These proteins form a stable, SDS-resistant, multimolecular complex, the SNARE complex. The subcellular distribution of VAMP and syntaxin within Torpedo electric organ nerve endings was studied by immunogoldlabeling of SDS-digested freeze-fracture replicas (Fujimoto, 1995).

A syntaxin-SNAP 25-VAMP complex is formed without docking of synaptic vesicles.

We show herein that syntaxin is already associated with SNAP 25 and VAMP during fast axonal transport, and in isolated synaptic vesicles, before docking of these secretory organelles at the active zones.