Saposin A, Human, Recombinant

Human lysosomes contain four homologous saposins (sphingolipid activator proteins), the saposins A, B, C, and D, which are derived from the prosaposin precursor protein (1, 2). Saposin A is small, cysteine-rich α-helical glycoprotein that exists in both soluble and lipid-bound states. Saposin A has roles in sphingolipid catabolism and transport and is required for the breakdown of galactosylceramide by β-galactosylceramidase to produce ceramide and galactose (3).  Saposins are glycosylated in a native state; however, non-glycosylated recombinant saposins produced in E. coli retain their respective activation effects in functional in vitro assays (2). Saposins are used as scaffolding proteins in a versa­tile lipid nanoparticle system to reconstitute membrane proteins in a lipid environment. Saposin-based nanoparticles may have a wide range of potential applications, from structural biology to the therapeutic delivery of protein-based pharmacological agents and vaccines (4). Recombinant