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Protein Page:
PSAP (human)
p Phosphorylation
ac Acetylation
me Methylation
m1 Mono-methylation
m2 Di-methylation
m3 Tri-methylation
ub Ubiquitylation
sm Sumoylation
ne Neddylation
gl O-GlcNAc
ga O-GalNAc
pa Palmitoylation
ad Adenylation
sn S-Nitrosylation
ca Caspase cleavage
sc Succinylation

Overview
PSAP The lysosomal degradation of sphingolipids takes place by the sequential action of specific hydrolases. Some of these enzymes require specific low-molecular mass, non-enzymic proteins: the sphingolipids activator proteins (coproteins). Defects in PSAP are the cause of combined saposin deficiency (CSAPD); also known as prosaposin deficiency. CSAPD is due to absence of all saposins, leading to a fatal storage disorder with hepatosplenomegaly and severe neurological involvement. Defects in PSAP saposin-B region are the cause of leukodystrophy metachromatic due to saposin-B deficiency (MLD- SAPB). MLD-SAPB is an atypical form of metachromatic leukodystrophy. It is characterized by tissue accumulation of cerebroside-3-sulfate, demyelination, periventricular white matter abnormalities, peripheral neuropathy. Additional neurological features include dysarthria, ataxic gait, psychomotr regression, seizures, cognitive decline and spastic quadriparesis. Defects in PSAP saposin-C region are the cause of atypical Gaucher disease (AGD). Affected individuals have marked glucosylceramide accumulation in the spleen without having a deficiency of glucosylceramide-beta glucosidase characteristic of classic Gaucher disease, a lysosomal storage disorder. Defects in PSAP saposin-A region are the cause of atypical Krabbe disease (AKRD). AKRD is a disorder of galactosylceramide metabolism. AKRD features include progressive encephalopathy and abnormal myelination in the cerebral white matter resembling Krabbe disease. Defects in PSAP saposin-D region are found in a variant of Tay-Sachs disease (GM2-gangliosidosis). 3 isoforms of the human protein are produced by alternative splicing. Note: This description may include information from UniProtKB.
Chromosomal Location of Human Ortholog: 10q21-q22
Cellular Component: cytoplasm; extracellular region; extracellular space; integral to membrane; lysosomal lumen; lysosomal membrane; mitochondrion
Molecular Function: enzyme activator activity; G-protein-coupled receptor binding; lipid binding; protein binding
Biological Process: G-protein signaling, adenylate cyclase inhibiting pathway; glycosphingolipid metabolic process; lipid transport; platelet degranulation; positive regulation of catalytic activity; positive regulation of MAPKKK cascade; regulation of autophagy; regulation of lipid metabolic process
Disease: Combined Saposin Deficiency; Gaucher Disease, Atypical, Due To Saposin C Deficiency; Krabbe Disease, Atypical, Due To Saposin A Deficiency; Metachromatic Leukodystrophy Due To Saposin B Deficiency
Reference #:  P07602 (UniProtKB)
Gene Symbols: PSAP
Molecular weight: 58,113 Da
Basal Isoelectric point: 5.06  Predict pI for various phosphorylation states
Select Structure to View Below

PSAP

Protein Structure Not Found.
Download PyMol Script
Download ChimeraX Script


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Modification Sites and Domains Show Modification Legend
Click here to view phosphorylation modifications only

Modification Sites in Parent Protein, Orthologs, and Isoforms Show Modification Legend
 

Show Multiple Sequence Alignment


 LTP 

LTP: The number of records in which this modification site was determined using site-specific methods. SS methods include amino acid sequencing, site-directed mutagenesis, modification site-specific antibodies, specific MS strategies, etc.


 HTP 

HTP: The number of records in which this modification site was assigned using ONLY proteomic discovery-mode mass spectrometry.


       human

► Hide Isoforms
 
0 1 T71‑p DICKDVVtAAGDMLK
0 1 T82‑p DMLKDNAtEEEILVy
0 1 Y89‑p tEEEILVyLEKTCDW
0 1 S112‑p SCKEIVDsyLPVILD
0 1 Y113‑p CKEIVDsyLPVILDI
0 1 K143‑ub NLCESLQkHLAELNH
0 1 K152‑ub LAELNHQkQLESNKI
0 1 T165‑p KIPELDMtEVVAPFM
0 1 Y180‑p ANIPLLLyPQDGPRs
0 1 S187‑p yPQDGPRsKPQPKDN
0 1 K303‑ub LELVEPIkKHEVPAK
0 1 K323‑ub EVCEFLVkEVTKLID
0 1 K336‑ub IDNNKTEkEILDAFD
0 1 T397‑ga GTRLPALtVHVtQPK
0 1 T401‑ga PALtVHVtQPKDGGF
0 2 K413‑ac GGFCEVCkKLVGyLD
0 1 Y418‑p VCkKLVGyLDRNLEK
0 1 Y447 CSFLPDPYQkQCDQF
0 1 K449‑ub FLPDPYQkQCDQFVA
  PSAP iso2  
T71 DICKDVVTAAGDMLK
T82 DMLKDNATEEEILVY
Y89 TEEEILVYLEKTCDW
S112 SCKEIVDSYLPVILD
Y113 CKEIVDSYLPVILDI
K143 NLCESLQKHLAELNH
K152 LAELNHQKQLESNKI
T165 KIPELDMTEVVAPFM
Y180 ANIPLLLYPQDGPRS
S187 YPQDGPRSKPQPKDN
K305 LELVEPIKKHEVPAK
K325 EVCEFLVKEVTKLID
K338 IDNNKTEKEILDAFD
T399 GTRLPALTVHVTQPK
T403 PALTVHVTQPKDGGF
K415 GGFCEVCKKLVGYLD
Y420 VCKKLVGYLDRNLEK
Y449 CSFLPDPYQKQCDQF
K451 FLPDPYQKQCDQFVA
  mouse

 
T71 DICKTVVTEAGNLLK
T82 NLLKDNATQEEILHY
Y89 TQEEILHYLEKTCEW
S112 SCKEVVDSYLPVILD
Y113 CKEVVDSYLPVILDM
E143 NLCQSLQEYLAEQNQ
K151 YLAEQNQKQLESNKI
A164 KIPEVDMARVVAPFM
Y179 SNIPLLLYPQDHPRS
S186 YPQDHPRSQPQPKAN
E305 LEMMDPYEQNLVQAH
N325 QTCQFVMNKFSELIV
E338 IVNNATEELLVKGLS
P430 QPKQSALPAHVPPQK
P434 SALPAHVPPQKNGGF
K446 GGFCEVCKKLVLYLE
Y451 VCKKLVLYLEHNLEK
Y480 CSFLPDPYQKQCDDF
K482 FLPDPYQKQCDDFVA
  rat

 
T71 DICKTVVTEAGNLLK
T82 NLLKDNATEEEILHY
Y89 TEEEILHYLEKTCAW
S112 SCKEVVDSYLPVILD
Y113 CKEVVDSYLPVILDM
E143 NLCQSLQEYLAEQNQ
R151 YLAEQNQRQLESNKI
A164 KIPEVDLARVVAPFM
Y179 SNIPLLLYPQDRPRS
S186 YPQDRPRSQPQPKAN
E302 LELTDPYEQDVIQAQ
R322 QVCQLVMRKLSELII
E335 IINNATEELLIKGLS
R427 EPKQSALRAHVPPQK
P431 SALRAHVPPQKNGGF
K443 GGFCEVCKKLVIYLE
Y448 VCKKLVIYLEHNLEK
Y477‑p CSFLPDPyQKQCDEF
K479 FLPDPyQKQCDEFVA
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