Aliases for PSAP Gene
External Ids for PSAP Gene
Previous HGNC Symbols for PSAP Gene
Previous GeneCards Identifiers for PSAP Gene
This gene encodes a highly conserved preproprotein that is proteolytically processed to generate four main cleavage products including saposins A, B, C, and D. Each domain of the precursor protein is approximately 80 amino acid residues long with nearly identical placement of cysteine residues and glycosylation sites. Saposins A-D localize primarily to the lysosomal compartment where they facilitate the catabolism of glycosphingolipids with short oligosaccharide groups. The precursor protein exists both as a secretory protein and as an integral membrane protein and has neurotrophic activities. Mutations in this gene have been associated with Gaucher disease and metachromatic leukodystrophy. Alternative splicing results in multiple transcript variants, at least one of which encodes an isoform that is proteolytically processed. [provided by RefSeq, Feb 2016]
GeneCards Summary for PSAP Gene
PSAP (Prosaposin) is a Protein Coding gene. Diseases associated with PSAP include Gaucher Disease, Atypical, Due To Saposin C Deficiency and Combined Saposin Deficiency. Among its related pathways are Response to elevated platelet cytosolic Ca2+ and Innate Immune System. Gene Ontology (GO) annotations related to this gene include lipid binding and enzyme activator activity. An important paralog of this gene is PSAPL1.
UniProtKB/Swiss-Prot for PSAP Gene
Saposin-A and saposin-C stimulate the hydrolysis of glucosylceramide by beta-glucosylceramidase (EC 126.96.36.199) and galactosylceramide by beta-galactosylceramidase (EC 188.8.131.52). Saposin-C apparently acts by combining with the enzyme and acidic lipid to form an activated complex, rather than by solubilizing the substrate.
Saposin-B stimulates the hydrolysis of galacto-cerebroside sulfate by arylsulfatase A (EC 184.108.40.206), GM1 gangliosides by beta-galactosidase (EC 220.127.116.11) and globotriaosylceramide by alpha-galactosidase A (EC 18.104.22.168). Saposin-B forms a solubilizing complex with the substrates of the sphingolipid hydrolases.
Saposin-D is a specific sphingomyelin phosphodiesterase activator (EC 22.214.171.124).
Prosaposin: Behaves as a myelinotrophic and neurotrophic factor, these effects are mediated by its G-protein-coupled receptors, GPR37 and GPR37L1, undergoing ligand-mediated internalization followed by ERK phosphorylation signaling.
Saposins are specific low-molecular mass non-enzymic proteins, they participate in the lysosomal degradation of sphingolipids, which takes place by the sequential action of specific hydrolases.