Search
proactivator polypeptide; saposin precursor; prosaposin (PSAP, GLBA)
Function:
1) lysosomal degradation of sphingolipids
2) precursor of saposins
- proteolytically processed to 4 small peptides (saposins), sphingolipid hydrolase activator peptides
Structure:
- contains 2 saposin A-type domains
- contains 4 saposin B-type domains
Compartment: lysosome
Alternative splicing: named isoforms=3
Additional isoforms seem to exist
Pathology:
1) defects in PSAP saposin-A region are the cause of atypical Krabbe disease
1) defects in PSAP saposin B region are a cause of metachromatic leukodystrophy variant
2) defects in PSAP saposin C region are a cause of Gaucher disease variant
3) defects in PSAP saposin D region are a cause of Tay-Sachs disease variant (GM2-gangliosidosis)
4) defects in PSAP are the cause of combined saposin deficiency
General
glycoprotein
protein precursor
Properties
SIZE: entity length = 524 aa
MW = 58 kD
COMPARTMENT: lysosome
MOTIF: signal sequence {1-16}
Saposin A-type 1 {18-58}
Saposin B-type 1 {59-142}
MOTIF: cysteine residue {C63}
MODIFICATION: cysteine residue {C138}
cysteine residue {C66}
MODIFICATION: cysteine residue {C132}
N-glycosylation site {N80}
cysteine residue {C94}
MODIFICATION: cysteine residue {C106}
N-glycosylation site {N101}
cysteine residue {C106}
MODIFICATION: cysteine residue {C94}
cysteine residue {C132}
MODIFICATION: cysteine residue {C66}
cysteine residue {C138}
MODIFICATION: cysteine residue {C63}
Saposin B-type 2 {194-275}
MOTIF: cysteine residue {C198}
MODIFICATION: cysteine residue {C271}
cysteine residue {C201}
MODIFICATION: cysteine residue {C265}
asparagine residue {215}
N-glycosylation site {N215}
cysteine residue {C230}
MODIFICATION: cysteine residue {C241}
cysteine residue {C241}
MODIFICATION: cysteine residue {C230}
cysteine residue {C265}
MODIFICATION: cysteine residue {C201}
cysteine residue {C271}
MODIFICATION: cysteine residue {C198}
Saposin B-type 3 {311-392}
MOTIF: cysteine residue {C315}
MODIFICATION: cysteine residue {C388}
cysteine residue {C318}
MODIFICATION: cysteine residue {C382}
N-glycosylation site {N332}
cysteine residue {C346}
MODIFICATION: cysteine residue {C357}
cysteine residue {C357}
MODIFICATION: cysteine residue {C346}
cysteine residue {C382}
MODIFICATION: cysteine residue {C318}
cysteine residue {C388}
MODIFICATION: cysteine residue {C315}
Saposin B-type 4 {405-486}
MOTIF: cysteine residue {C409}
MODIFICATION: cysteine residue {C482}
cysteine residue {C412}
MODIFICATION: cysteine residue {C476}
N-glycosylation site {N426}
cysteine residue {C440}
MODIFICATION: cysteine residue {C451}
cysteine residue {C451}
MODIFICATION: cysteine residue {C440}
cysteine residue {C476}
MODIFICATION: cysteine residue {C412}
cysteine residue {C482}
MODIFICATION: cysteine residue {C409}
Saposin A-type 2 {488-524}
PRECURSOR-FOR: saposin
Database Correlations
OMIM correlations
MORBIDMAP 176801
UniProt P07602
PFAM correlations
Entrez Gene 5660
Kegg hsa:5660
References
- UniProt :accession P07602
- Atlas of genetics & cytogenetics in oncology & haematology
http://atlasgeneticsoncology.org/genes/PSAPID42980ch10q22.html
- GeneReviews
https://www.genecards.org/cgi-bin/carddisp.pl?gene=PSAP