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Gene Review

Psap  -  prosaposin

Mus musculus

Synonyms: AI037048, Prosaposin, SGP-1, Sgp1, Sulfated glycoprotein 1
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Disease relevance of Psap


High impact information on Psap


Chemical compound and disease context of Psap

  • We conclude that in breast cancer cells, even though procath-D interacts intracellularly and extracellarly with prosaposin, it is endocytosed independent of prosaposin by a receptor different from the M6P receptors and the LRP [5].
  • CONCLUSION: We postulate that as a mitogenic, survival, and anti-apoptotic factor for prostate cancer cells, saposin C or prosaposin may contribute to prostate carcinogenesis at its early androgen-dependent or metastatic AI state [8].

Biological context of Psap


Anatomical context of Psap

  • Interestingly, dominant-negative GGAs, unable to bind clathrin to shuttle from the Golgi, prevented the trafficking of prosaposin and GM2AP to lysosomes [2].
  • Prosaposin (SGP-1) and GM2 activator protein (GM2AP) are soluble sphingolipid activator proteins (SAPs) that are targeted to the lysosomal compartment of Sertoli cells to aid hydrolases in the breakdown of glycosphingolipids [2].
  • Using a TM4 Sertoli cell line, we tested the hypothesis that prosaposin and GM2AP are targeted to the lysosomal compartment via the sortilin receptor, which has been recently shown to have a GGA binding motif [2].
  • Concordant decreases (>50%) of GCase protein and in vitro activity were detected in extracts of cultured fibroblasts and hepatocytes from PS-/- mice and human prosaposin-deficient fibroblasts [13].
  • Prosaposin was initially identified in Sertoli cells, found in large amounts in the lysosomal compartment and implicated in the degradation of residual bodies released by the spermatids during spermiation [14].

Associations of Psap with chemical compounds

  • The visceral tissue storage cells and glucosylceramide (GC) accumulation in hGCase/4L/PS-NA were decreased from that in 4L/PS-NA mice [1].
  • The hGCase/4L/PS-NA had exclusive liver expression of hGCase controlled by doxycycline (DOX) [1].
  • Prosaposin is the precursor of four glycoprotein activators (saposins) for lysosomal hydrolases [3].
  • A mutation in the saposin A domain of the sphingolipid activator protein (prosaposin) gene results in a late-onset, chronic form of globoid cell leukodystrophy in the mouse [15].
  • No changes were detected in prosaposin secretion or in accumulation and metabolism of gangliosides, sulfatides, neutral glycosphingolipids, neutral phospholipids, other neutral lipids, and ceramide [12].

Physical interactions of Psap


Regulatory relationships of Psap


Other interactions of Psap


Analytical, diagnostic and therapeutic context of Psap


  1. Conditional expression of human acid {beta}-glucosidase improves the visceral phenotype in a Gaucher disease mouse model. Sun, Y., Quinn, B., Xu, Y.H., Leonova, T., Witte, D.P., Grabowski, G.A. J. Lipid Res. (2006) [Pubmed]
  2. The trafficking of prosaposin (SGP-1) and GM2AP to the lysosomes of TM4 Sertoli cells is mediated by sortilin and monomeric adaptor proteins. Hassan, A.J., Zeng, J., Ni, X., Morales, C.R. Mol. Reprod. Dev. (2004) [Pubmed]
  3. Prosaposin: threshold rescue and analysis of the "neuritogenic" region in transgenic mice. Sun, Y., Qi, X., Witte, D.P., Ponce, E., Kondoh, K., Quinn, B., Grabowski, G.A. Mol. Genet. Metab. (2002) [Pubmed]
  4. Targeted disruption of the mouse prosaposin gene affects the development of the prostate gland and other male reproductive organs. Morales, C.R., Zhao, Q., El-Alfy, M., Suzuki, K. J. Androl. (2000) [Pubmed]
  5. Procathepsin D interacts with prosaposin in cancer cells but its internalization is not mediated by LDL receptor-related protein. Laurent-Matha, V., Lucas, A., Huttler, S., Sandhoff, K., Garcia, M., Rochefort, H. Exp. Cell Res. (2002) [Pubmed]
  6. Cell death prevention, mitogen-activated protein kinase stimulation, and increased sulfatide concentrations in Schwann cells and oligodendrocytes by prosaposin and prosaptides. Hiraiwa, M., Taylor, E.M., Campana, W.M., Darin, S.J., O'Brien, J.S. Proc. Natl. Acad. Sci. U.S.A. (1997) [Pubmed]
  7. Identification of prosaposin as a neurotrophic factor. O'Brien, J.S., Carson, G.S., Seo, H.C., Hiraiwa, M., Kishimoto, Y. Proc. Natl. Acad. Sci. U.S.A. (1994) [Pubmed]
  8. Saposin C promotes survival and prevents apoptosis via PI3K/Akt-dependent pathway in prostate cancer cells. Lee, T.J., Sartor, O., Luftig, R.B., Koochekpour, S. Mol. Cancer (2004) [Pubmed]
  9. Genetic mapping of the mouse prosaposin gene (Psap) to mouse chromosome 10. Kozak, C.A., Adamson, M.C., Horowitz, M. Genomics (1994) [Pubmed]
  10. Sphingolipid activator proteins are required for epidermal permeability barrier formation. Doering, T., Holleran, W.M., Potratz, A., Vielhaber, G., Elias, P.M., Suzuki, K., Sandhoff, K. J. Biol. Chem. (1999) [Pubmed]
  11. Gaucher disease mouse models: point mutations at the acid beta-glucosidase locus combined with low-level prosaposin expression lead to disease variants. Sun, Y., Quinn, B., Witte, D.P., Grabowski, G.A. J. Lipid Res. (2005) [Pubmed]
  12. The exon 8-containing prosaposin gene splice variant is dispensable for mouse development, lysosomal function, and secretion. Cohen, T., Auerbach, W., Ravid, L., Bodennec, J., Fein, A., Futerman, A.H., Joyner, A.L., Horowitz, M. Mol. Cell. Biol. (2005) [Pubmed]
  13. Saposin C is required for normal resistance of acid beta-glucosidase to proteolytic degradation. Sun, Y., Qi, X., Grabowski, G.A. J. Biol. Chem. (2003) [Pubmed]
  14. Study of the mouse sortilin gene: Effects of its transient silencing by RNA interference in TM4 Sertoli cells. Zeng, J., Hassan, A.J., Morales, C.R. Mol. Reprod. Dev. (2004) [Pubmed]
  15. A mutation in the saposin A domain of the sphingolipid activator protein (prosaposin) gene results in a late-onset, chronic form of globoid cell leukodystrophy in the mouse. Matsuda, J., Vanier, M.T., Saito, Y., Tohyama, J., Suzuki, K., Suzuki, K. Hum. Mol. Genet. (2001) [Pubmed]
  16. In vivo roles of RORalpha and Sp4 in the regulation of murine prosaposin gene. Jin, P., Sun, Y., Grabowski, G.A. DNA Cell Biol. (2001) [Pubmed]
  17. Identification of a novel sequence involved in lysosomal sorting of the sphingolipid activator protein prosaposin. Zhao, Q., Morales, C.R. J. Biol. Chem. (2000) [Pubmed]
  18. Structural analysis of the mouse prosaposin (SGP-1) gene reveals the presence of an exon that is alternatively spliced in transcribed mRNAs. Zhao, Q., Hay, N., Morales, C.R. Mol. Reprod. Dev. (1997) [Pubmed]
  19. Developmental and tissue-specific expression of prosaposin mRNA in murine tissues. Sun, Y., Witte, D.P., Grabowski, G.A. Am. J. Pathol. (1994) [Pubmed]
  20. Murine prosaposin: expression in the reproductive system of a gene implicated in human genetic diseases. Sprecher-Levy, H., Orr-Urtreger, A., Lonai, P., Horowitz, M. Cell. Mol. Biol. (Noisy-le-grand) (1993) [Pubmed]
  21. Structural requirements for lysosomal targeting of the prosaposin precursor protein. Ham, D. Cell Biol. Int. (2003) [Pubmed]
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