Snapin: a SNARE-associated protein implicated in synaptic transmission

Synaptic vesicle docking and fusion are mediated by the assembly of a stabl e SNARE core complex of proteins, which include the synaptic vesicle membra ne protein VAMP/synaptobrevin and the plasmalemmal proteins syntaxin and SN AP-25. We have now identified another SNAP-25-binding protein, called Snapi n. Snapin was enriched in neurons and exclusively located on synaptic vesic le membranes. It associated with the SNARE complex through direct interacti on with SNAP-25. Binding of recombinant Snapin-CT to SNAP-25 blocked the as sociation of the SNARE complex with synaptotagmin. Introduction of Snapin-C T and peptides containing the SNAP-25 binding sequence into presynaptic sup erior cervical ganglion neurons in culture reversibly inhibited synaptic tr ansmission. These results suggest that Snapin is an important component of the neurotransmitter release process through its modulation of the sequenti al interactions between the SNAREs and synaptotagmin.