Saposin-B stimulates the hydrolysis of galacto-cerebroside sulfate by arylsulfatase A (EC 3.1.6.8), GM1 gangliosides by beta-galactosidase (EC 3.2.1.23) and globotriaosylceramide by alpha-galactosidase A (EC 3.2.1.22). Saposin-B forms a solubilizing complex with the substrates of the sphingolipid hydrolases. Saposin-B is a homodimer. Interacts with GRN; facilitates lysosomal delivery of progranulin from the extracellular space and the biosynthetic pathway (By similarity). The one residue extended Saposin-B-Val is only found in a minority of the chains.