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Synaptosomal-associated protein 25, also known as Super protein, Synaptosomal-associated 25 kDa protein, SNAP25 and SNAP, is a cytoplasm and cell membrane protein that 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.