NAPA is one of the SNAP (Soluble NSF Attachment Protein) family. SNAPs, acting in concert with SNAREs (SNAP receptors) and the N-ethylmaleimide-sensitive fusion protein (NSF), are required for the fusion of transport vesicles to their target membranes in synaptic transmission, intra-Golgi transport, endosome-to-endosome fusion and transcytotic vesicles-to-plasma membrane transport.