Gamma-SNAP (NAPG) is a cytoplasmic protein which binds to a membrane receptor complex composed of VAMP, SNAP25 and syntaxin. NAPG mediates the membrane binding of NSF, which is crucial for membrane fusion reactions. NSF and SNAPs seem to be general components of the intracellular membrane fusion system, and their action at specific sites of fusion needs be controlled by SNAP receptors specific to the membranes being fused. NAPG mediates platelet exocytosis and controls the membrane fusion events of this process.