DOCKING AND FUSION IN NEUROSECRETION

A central issue in neurobiology concerns the mechanisms of membrane fu sion that are essential for the rapid regulated delivery of neurotrans mitters into the synapse. While many gene products are required for ne urosecretion, recent research has focused on defining the core exocyto tic machinery that is responsible for the docking of synaptic vesicles (SVs) and their fusion with the plasma membrane. N-ethylmaleimide-sen sitive factor (NSF), soluble NSF attachment protein (SNAP) and SNAP re ceptor (SNARE) proteins are essential for fusion but may not be critic al for SV docking. Current evidence suggests that NSF functions during an ATP-dependent step after docking but before fusion. NSF may functi on to liberate SNARE proteins from complexes so that the proteins on a pposed membranes align in a parallel fashion to bring SVs into close c ontact with the plasma membrane for fusion.