InterPro domain: IPR017246

Snapin is a component of the biogenesis of lysosomal organelles complex-1 (BLOC-1), a complex required for the normal biogenesis of lysosome-related organelles, such as melanosomes and platelet dense granules [ 1 ], and endosomal cargo sorting [ 2 ].

Snapin binds to SNAP-25, part of the SNARE complex that mediates the synaptic vesicle docking and fusion [ 3 ]. Snapin may modulate a step between vesicle priming, fusion and calcium-dependent neurotransmitter release through its ability to potentiate the interaction of synaptotagmin with the SNAREs and the plasma-membrane-associated protein SNAP25 [ 4 ]. Its phosphorylation state influences exocytotic protein interactions and may regulate synaptic vesicle exocytosis [ 4 , 5 ]. It may also have a role in the mechanisms of SNARE-mediated membrane fusion in non-neuronal cells [ 6 ].

1. Identification of snapin and three novel proteins (BLOS1, BLOS2, and BLOS3/reduced pigmentation) as subunits of biogenesis of lysosome-related organelles complex-1 (BLOC-1). J. Biol. Chem. 279, 28393-401
2. BLOC-1 is required for cargo-specific sorting from vacuolar early endosomes toward lysosome-related organelles. Mol. Biol. Cell 18, 768-80
3. Snapin: a SNARE-associated protein implicated in synaptic transmission. Nat. Neurosci. 2, 119-24
4. Phosphorylation of Snapin by PKA modulates its interaction with the SNARE complex. Nat. Cell Biol. 3, 331-8
5. Regulation of the exocytotic machinery by cAMP-dependent protein kinase: implications for presynaptic plasticity. Biochem. Soc. Trans. 31, 824-7
6. The SNARE-associated component SNAPIN binds PUMILIO2 and NANOS1 proteins in human male germ cells. Mol. Hum. Reprod. 15, 173-9