PSAP

The protein is proteolytically processed to generate four saposins (A-D) that localize to lysosomes and facilitate the catabolism of glycosphingolipids with short oligosaccharide groups. Mutations cause autosomal recessive lysosomal storage disorders including combined saposin deficiency, metachromatic leukodystrophy due to saposin B deficiency, and atypical forms of Gaucher and Krabbe diseases, as well as autosomal dominant susceptibility to Parkinson disease. The pathogenic mechanism involves impaired glycosphingolipid degradation due to deficient saposin cofactor function.