O13035 · SAP_CHICK

Function

function

The lysosomal degradation of sphingolipids takes place by the sequential action of specific hydrolases. Some of these enzymes require specific low-molecular mass, non-enzymatic proteins: the sphingolipids activator proteins (coproteins).
Saposin-A and saposin-C stimulate the hydrolysis of glucosylceramide by beta-glucosylceramidase (EC 3.2.1.45) and galactosylceramide by beta-galactosylceramidase (EC 3.2.1.46). 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 3.1.6.8), GM1 gangliosides by beta-galactosidase (EC 3.2.1.23) and globotriaosylceramide by alpha-galactosidase A (EC 3.2.1.22). Saposin-B forms a solubilizing complex with the substrates of the sphingolipid hydrolases.
Saposin-D is a specific sphingomyelin phosphodiesterase activator (EC 3.1.4.12).

GO annotations

all annotationsall molecular functionvirus receptor activitydna bindingrna bindingcytoskeletal motor activitycatalytic activitygtpase activitystructural molecule activitytransporter activitycytoskeletal protein bindinglipid bindingcyclase activityantioxidant activityoxidoreductase activitytransferase activityhydrolase activitylyase activityisomerase activityligase activityprotein tag activitycargo receptor activityhistone bindingprotein folding chaperonetranslation regulator activitynutrient reservoir activityreceptor ligand activitymolecular transducer activitymolecular adaptor activitytoxin activitycell adhesion mediator activitymolecular function regulator activityvirus coreceptor activitycatalytic activity, acting on a proteincatalytic activity, acting on dnacatalytic activity, acting on rnamolecular carrier activitytranscription regulator activitygeneral transcription initiation factor activitymolecular sensor activitymolecular sequestering activityatp-dependent activityother molecular functionall biological processmitotic cell cyclecytokinesiscytoplasmic translationimmune system processmuscle system processcirculatory system processrenal system processrespiratory system processcarbohydrate metabolic processgeneration of precursor metabolites and energydna replicationdna repairdna recombinationchromatin organizationdna-templated transcriptionregulation of dna-templated transcriptiontrna metabolic processprotein foldingprotein glycosylationamino acid metabolic processmodified amino acid metabolic processlipid metabolic processvitamin metabolic processsulfur compound metabolic processintracellular protein transportnucleocytoplasmic transportautophagyinflammatory responsemitochondrion organizationcytoskeleton organizationmicrotubule-based movementperoxisome organizationlysosome organizationchromosome segregationcell adhesionestablishment or maintenance of cell polarityprogrammed cell deathphotosynthesismrna metabolic processsnrna metabolic processvesicle-mediated transportreproductive processdigestive system processsignalingcell differentiationprotein catabolic processextracellular matrix organizationregulatory ncrna-mediated gene silencingtelomere organizationcell junction organizationwound healingribosome biogenesiscilium organizationanatomical structure developmentcell motilitynervous system processendocrine processprotein maturationtransmembrane transportnucleobase-containing small molecule metabolic processhepaticobiliary system processmembrane organizationprotein-containing complex assemblycell wall organization or biogenesisnitrogen cycle metabolic processprotein localization to plasma membranedefense response to other organismdetoxificationmeiotic nuclear divisionmitotic nuclear divisionmitochondrial gene expressioncarbohydrate derivative metabolic processother biological processall cellular componentnuclear chromosomeextracellular regionextracellular spacecell wallnucleusnuclear envelopenucleoplasmchromosomenucleolusmitochondrionlysosomeendosomevacuoleperoxisomeendoplasmic reticulumgolgi apparatuslipid dropletmicrotubule organizing centercytosolribosomecytoskeletonplasma membraneciliumplastidthylakoidexternal encapsulating structureextracellular matrixcytoplasmic vesicleorganelleother cellular component
Cell color indicative of number of GO terms
AspectTerm
Cellular Componentextracellular region
Cellular Componentlysosome
Biological Processadenylate cyclase-inhibiting G protein-coupled receptor signaling pathway
Biological Processregulation of lipid metabolic process
Biological Processsphingolipid metabolic process

Keywords

Names & Taxonomy

Protein names

Gene names

    • Name
      PSAP

Organism names

  • Taxonomic identifier
  • Taxonomic lineage
    Eukaryota > Metazoa > Chordata > Craniata > Vertebrata > Euteleostomi > Archelosauria > Archosauria > Dinosauria > Saurischia > Theropoda > Coelurosauria > Aves > Neognathae > Galloanserae > Galliformes > Phasianidae > Phasianinae > Gallus

Accessions

  • Primary accession
    O13035

Proteomes

Organism-specific databases

Subcellular Location

Lysosome

Prosaposin

Secreted
Note: Secreted as a fully glycosylated 70 kDa protein composed of complex glycans.

Keywords

Phenotypes & Variants

Keywords

PTM/Processing

Features

Showing features for signal, propeptide, chain, disulfide bond, glycosylation.

TypeIDPosition(s)Description
Signal1-17
PropeptidePRO_000003163018-60
ChainPRO_000043497318-518Prosaposin
ChainPRO_000003163161-143Saposin-A
Disulfide bond64↔139
Disulfide bond67↔133
Glycosylation81N-linked (GlcNAc...) asparagine
Disulfide bond95↔107
PropeptidePRO_0000031632144-193
ChainPRO_0000031633194-276Saposin-B
Disulfide bond197↔273
Disulfide bond200↔267
Glycosylation214N-linked (GlcNAc...) asparagine
Disulfide bond229↔240
PropeptidePRO_0000031634277-306
ChainPRO_0000031635307-387Saposin-C
Disulfide bond311↔384
Disulfide bond314↔378
Glycosylation328N-linked (GlcNAc...) asparagine
Disulfide bond342↔353
PropeptidePRO_0000031636388-398
ChainPRO_0000031637399-479Saposin-D
Disulfide bond403↔476
Disulfide bond406↔470
Glycosylation420N-linked (GlcNAc...) asparagine
Disulfide bond434↔445
PropeptidePRO_0000031638480-518

Post-translational modification

This precursor is proteolytically processed to 4 small peptides, which are similar to each other and are sphingolipid hydrolase activator proteins.

Keywords

Proteomic databases

PTM databases

Interaction

Subunit

Saposin-B is a homodimer.

Protein-protein interaction databases

Structure

Family & Domains

Features

Showing features for domain.

TypeIDPosition(s)Description
Domain19-59Saposin A-type 1
Domain60-143Saposin B-type 1
Domain193-277Saposin B-type 2
Domain307-388Saposin B-type 3
Domain399-480Saposin B-type 4
Domain482-518Saposin A-type 2

Keywords

Phylogenomic databases

Family and domain databases

Sequence

  • Sequence status
    Complete
  • Sequence processing
    The displayed sequence is further processed into a mature form.
  • Length
    518
  • Mass (Da)
    57,601
  • Last updated
    1997-07-01 v1
  • Checksum
    B803000E891C3963
MARRLLTLLGLLAAAVASPVLWQKDCAKGPEVWCQSLRTASQCGAVKHCQQNVWSKPAVNSIPCDLCKELVTVVGKVLKDNGTEDEIRSYLEKRCEFLPDQGLASECKEIVDSYLPVIMDMIKEEFDKPEVVCSALSLCQSLQKHLAAMKLQKQLQSNKIPELDFSELTSPFMANVPLLLYPQDKPKQKSKATEDVCQDCIRLVTDVQEAVRTNATFVKSLVAHAKEECDRLGPGMSDMCKSYISEYSDLAIQMMMHMKDQQPKDICAMVGFCPSVKSVPLQTLVPAQVVHEVKMETVEKATVQEKTFSVCEICETMVKEVTGLLESNKTEEEIVHEMEVVCYLLPASVKDQCKDFIEVYGQALIDMLLEATNPEAVCVMLKCCAANKPPQQPVVVKPAGGFCDICKMIVAYADKELEKNATTTEIEALLEKVCHFLPESVSDQCVQFVEQYEPVVVQLLAEMMDPTFVCTKLGVCGAAKKPLLGEDACVWGPGYWCKNMETAAQCNAVDHCRRHVWN

Features

Showing features for sequence conflict.

TypeIDPosition(s)Description
Sequence conflict94in Ref. 2; AAF05899
Sequence conflict486in Ref. 2; AAF05899

Keywords

Sequence databases

Nucleotide SequenceProtein SequenceMolecule TypeStatus
AB003471
EMBL· GenBank· DDBJ
BAA19914.1
EMBL· GenBank· DDBJ
mRNA
AF108656
EMBL· GenBank· DDBJ
AAF05899.1
EMBL· GenBank· DDBJ
mRNA

Genome annotation databases

Similar Proteins

Disclaimer

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