SNAP Associated Protein (SNAPAP)

SNAPAP is a component of the SNARE complex of proteins that is required for synaptic vesicle docking and fusion. SNAPAP is also a component of the ubiquitously expressed BLOC1 multisubunit protein complex. The deduced 136-amino acid protein has a calculated molecular mass of 15 kD. It contains an N-terminal hydrophobic segment characteristic of a transmembrane domain and a coiled-coil C-terminal region. SNAPAP shares 98% sequence identity with the mouse homolog. Western blot analysis of various rat tissues showed SNAPAP almost exclusively in brain and synaptosome preparations. Further analysis indicated SNAPAP in all 12 rat brain areas examined; fractionation of rat cerebral synaptosomes indicated that SNAPAP partitions with the synaptic vesicle fraction and not with cytosolic or plasma membrane fractions.