Synaptosomal-associated protein 25, also known as Super protein, Synaptosomal-associated 25 kDa protein, SNAP25 and SNAP, is a cytoplasm and cell membrane protein which belongs to the SNAP-25 family. SNAP25 / SUP contains 2 t-SNARE coiled-coil homology domains. SNAP25 / SUP is a membrane bound protein anchored to the cytosolic face of membranes via palmitoyl side chains in the middle of the molecule. SNAP25 / SUP protein 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. SNAP25 / SUP is a Q-SNARE protein contributing two α-helices in the formation of the exocytotic fusion complex in neurons where it assembles with syntaxin-1 and synaptobrevin. SNAP25 / SUP is involved in the molecular regulation of neurotransmitter release. It may play an important role in the synaptic function of specific neuronal systems. SNAP25 / SUP associates with proteins involved in vesicle docking and membrane fusion. SNAP25 / SUP regulates plasma membrane recycling through its interaction with CENPF. SNAP25 / SUP inhibits P/Q- and L-type voltage-gated calcium channels located presynaptically and interacts with the synaptotagmin C2B domain in Ca2+-independent fashion. In glutamatergic synapses SNAP25 / SUP decreases the Ca2+ responsiveness, while it is naturally absent in GABAergic synapses.