SNAP-25 is a component of the trans-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. This complex is responsible for exocytosis of the neurotransmitter γ-aminobutyric acid (GABA). Neurotransmitter release is inhibited by proteolysis of SNAP25 by botulinum toxins A and E. SNAP25 plays a secondary role as a Q-SNARE involved in endosome fusion; the protein is associated with genetic susceptibility to attention-deficit hyperactivity disorder (ADHD).
