The protein is a coiled-coil protein and belongs to a family found in eukaryotes. It undergoes alternative splicing forming two isoforms. The larger isoform is 187 amino acids long in protein sequence length and 21 kDa in mass. The smaller isoform is 110 amino acids long in protein sequence length and 12 kDa in mass. This protein associates with other proteins in order to form biogenesis of lysosome-related organelles complex-1 BLOC1 complex. BLOC-1 is required for the normal biogenesis of specialized organelles of the endosomal-lysosomal system [1].

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). Starcevic M, Dell'Angelica EC; J Biol Chem. 2004;279:28393-28401. PMID:15102850