PSAP gets cleaved

Stable Identifier
Reaction [uncertain]
Homo sapiens
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After its transport to lysosomes, prosaposin (PSAP) gets cleaved by unknown proteases into the fragments PSAP(60-142) (Saposin A), PSAP(195-273) (Saposin B), PSAP(311-391) (Saposin C) and PSAP(405-486) (Saposin D). Intermediate polyproteins during cleavage appear to be B-C-D, B-C, and C-D (Furst et al., 1988; Leonova et al., 1996; saposins were reviewed by O'Brien & Kishimoto, 1991; Morales et al., 1995; Kolter et al., 2005: Kolter & Sandhoff, 2010; Garrido-Arandia et al., 2018). Bioinformatics suggests that different peptidases, including trypsin, may be responsible for cleavage at different PSAP cleavage sites. In its dimerized form PSAP(195-273) (Saposin B) is centrally involved in mobilizing glycosphingolipids for catabolism, while PSAP(60-142) (Saposin A) and PSAP(405-486) (Saposin D) activate GALC and ASAH1, respectively.
Literature References
PubMed ID Title Journal Year
16230343 Lipid-binding proteins in membrane digestion, antigen presentation, and antimicrobial defense

Leippe, M, Kolter, T, Winau, F, Schaible, UE, Sandhoff, K

J Biol Chem 2005
3048308 The precursor of sulfatide activator protein is processed to three different proteins

Fürst, W, Machleidt, W, Sandhoff, K

Biol Chem Hoppe Seyler 1988
8573994 Molecular role of sulfated glycoprotein-1 (SGP-1/prosaposin) in Sertoli cells

Igdoura, S, Zhao, Q, Morales, CR, el-Alfy, M

Histol Histopathol 1995
2001789 Saposin proteins: structure, function, and role in human lysosomal storage disorders

Kishimoto, Y, O'Brien, JS

FASEB J 1991
8663398 Proteolytic processing patterns of prosaposin in insect and mammalian cells

Bencosme, A, Sun, Y, Grabowski, GA, Leonova, T, Ponce, E, Qi, X

J Biol Chem 1996
29443946 A Comparative Study of Human Saposins

Cuevas-Zuviría, B, Díaz-Perales, A, Pacios, LF, Garrido-Arandia, M

Molecules 2018
19836391 Lysosomal degradation of membrane lipids

Kolter, T, Sandhoff, K

FEBS Lett 2010
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