Synaptosomal-associated protein 25 (SNAP-25) is a membrane bound protein anchored to the cytosolic face of membrane via palmitoyl side chains in the middle of the molecule (1). It is a component of the SNARE complex, which is proposed to account for the specificity of membrane fusion and to directly execute fusion by forming a tight complex that brings the synaptic vesicle and plasma membranes together (2).
SNAP25 exists as two alternatively spliced isoforms, SMAP25A and SNAP25B. These isoforms are differentially expressed in neurons and neuroendocrine cells and they differ by 9 amino acids in the central portion of the protein (3).