Prosaposin Like Protein 1 (PSAPL1)

PSAPL1 is a 521 secreted protein that contains two saposin A-type domains and four saposin B-type domains. It is suggested that PSAPL1 may activate the lysosomal degradation of sphingolipids. The gene encoding PSAPL1 is located on chromosome 4, which encodes nearly 6% of the human genome and has the largest gene deserts of all of the human chromosomes. The saposin family includes four structurally related activator proteins, saposin A, B, C and D, that are cleaved from the single precursor protein prosaposin. Prosaposin is synthesized as a protein that is post-translationally modified to a shorter form and then further glycosylated to yield a secretory product. This form subsequently undergoes partial proteolysis to produce saposin A, B, C and D. Each saposin family member acts in conjunction with hydrolase enzymes to facilitate the breakdown of glycosphingolipids within the lysosome.