id: P51688
gene_symbol: SGSH
product_type: PROTEIN
status: INITIALIZED
taxon:
  id: NCBITaxon:9606
  label: Homo sapiens
description: >-
  SGSH encodes N-sulphoglucosamine sulphohydrolase (sulfamidase, also called heparan
  N-sulfatase; EC 3.10.1.1), a lysosomal enzyme of the sulfatase family. It acts in the
  stepwise exolytic degradation of the glycosaminoglycan heparan sulfate, hydrolytically
  removing the N-sulfate group from terminal N-sulfo-D-glucosamine residues (yielding
  D-glucosamine with a free amino group plus sulfate). Like other sulfatases, its activity
  depends on a catalytic formylglycine residue (Cys70 converted to 3-oxoalanine) generated
  post-translationally in the endoplasmic reticulum by the formylglycine-generating enzyme
  SUMF1; the active site also binds a Ca2+ ion. The synthesized precursor is trafficked to
  the lysosome, where the mature enzyme resides in the lysosomal lumen. Loss of SGSH activity
  blocks heparan sulfate catabolism, causing its lysosomal accumulation and the autosomal
  recessive lysosomal storage disease mucopolysaccharidosis type IIIA (Sanfilippo syndrome A),
  characterized by progressive central nervous system neurodegeneration with comparatively
  mild somatic features.
references:
- id: GO_REF:0000033
  title: Annotation inferences using phylogenetic trees
  findings: []
- id: GO_REF:0000044
  title: Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location
    vocabulary mapping, accompanied by conservative changes to GO terms applied by
    UniProt
  findings: []
- id: GO_REF:0000120
  title: Combined Automated Annotation using Multiple IEA Methods
  findings: []
- id: PMID:15146460
  title: Transport, enzymatic activity, and stability of mutant sulfamidase (SGSH)
    identified in patients with mucopolysaccharidosis type III A.
  findings: []
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: >-
      PubMed-verified primary study of recombinant SGSH and MPS IIIA mutants; confirms
      lysosomal localisation, N-sulfoglucosamine sulfohydrolase activity, and heparan
      sulfate catabolic role. Abstract-only cache; supporting quotes drawn from the abstract.
- id: PMID:15962010
  title: Sulphatase activities are regulated by the interaction of sulphatase-modifying
    factor 1 with SUMF2.
  findings: []
  reference_review:
    relevance: MEDIUM
    correctness: VERIFIED
    review_notes: >-
      Establishes physical association of the SUMF1/SUMF2 formylglycine-generating machinery
      with sulphatases including SGSH; corroborates the SGSH-SUMF1 interaction underlying the
      protein-binding IPIs, though "protein binding" itself is uninformative.
- id: PMID:23533145
  title: In-depth proteomic analyses of exosomes isolated from expressed prostatic
    secretions in urine.
  findings: []
  reference_review:
    relevance: LOW
    correctness: VERIFIED
    review_notes: >-
      Large-scale exosome proteomics; SGSH detected in urinary prostatic-secretion exosomes.
      Reflects secretome contamination of a lysosomal enzyme, not its functional site of action.
- id: PMID:24816101
  title: Structure of sulfamidase provides insight into the molecular pathology of
    mucopolysaccharidosis IIIA.
  findings: []
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: >-
      Crystal structure of glycosylated SGSH (PDB 4MHX/4MIV); documents the sulfatase fold,
      catalytic formylglycine (Cys70), Ca2+ site, N-sulfate binding, and catalysis of N-linked
      sulfate cleavage from heparan sulfate/heparin. Directly supports MF and family assignment.
- id: PMID:33961781
  title: Dual proteome-scale networks reveal cell-specific remodeling of the human
    interactome.
  findings: []
  reference_review:
    relevance: LOW
    correctness: VERIFIED
    review_notes: >-
      High-throughput AP-MS interactome (BioPlex); source of a bare protein-binding IPI
      (SGSH-SUMF1). Consistent with the known SGSH-SUMF1 relationship but not functionally
      informative on its own.
- id: PMID:40205054
  title: Multimodal cell maps as a foundation for structural and functional genomics.
  findings: []
  reference_review:
    relevance: LOW
    correctness: VERIFIED
    review_notes: >-
      Multimodal cell-map / interactome resource; source of a bare protein-binding IPI
      (SGSH-SUMF1). Contextual only.
- id: PMID:7493035
  title: Cloning of the sulphamidase gene and identification of mutations in Sanfilippo
    A syndrome.
  findings: []
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: >-
      Original cloning of SGSH/sulphamidase (EC 3.10.1.1); establishes the enzyme's role in
      lysosomal heparan sulphate degradation and its causal link to Sanfilippo A (MPS IIIA).
- id: Reactome:R-HSA-1678708
  title: SGSH hydrolyses Heparan sulfate chain(2)
  findings: []
- id: Reactome:R-HSA-2090043
  title: SGSH hydrolyses Heparan sulfate chain(7)
  findings: []
- id: Reactome:R-HSA-2263444
  title: Defective SGSH does not hydrolyse Heparan sulfate chain(7)
  findings: []
- id: Reactome:R-HSA-9036050
  title: Defective SGSH does not hydrolyse Heparan sulfate chain(2)
  findings: []
- id: file:human/SGSH/SGSH-uniprot.txt
  title: UniProtKB P51688 (SPHM_HUMAN) N-sulphoglucosamine sulphohydrolase
  findings: []
existing_annotations:
- term:
    id: GO:0005764
    label: lysosome
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: is_active_in
  review:
    summary: >-
      Phylogenetically inferred lysosomal localisation, consistent with SGSH's site of action
      in heparan sulfate degradation and with direct experimental localisation.
    action: ACCEPT
    reason: >-
      SGSH is a lysosomal sulfatase; lysosomal localisation is directly demonstrated
      experimentally (PMID:15146460) and stated by UniProt, so the IBA is well supported and
      represents a core aspect of the gene product.
    supported_by:
    - reference_id: file:human/SGSH/SGSH-uniprot.txt
      supporting_text: "SUBCELLULAR LOCATION: Lysosome"
- term:
    id: GO:0016250
    label: N-sulfoglucosamine sulfohydrolase activity
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: enables
  review:
    summary: >-
      Phylogenetically inferred N-sulfoglucosamine sulfohydrolase activity, the defining
      molecular function of SGSH (EC 3.10.1.1).
    action: ACCEPT
    reason: >-
      This is the exact molecular function of SGSH, independently supported by direct enzyme
      assays and structural work. The IBA correctly captures the core catalytic activity.
    supported_by:
    - reference_id: PMID:24816101
      supporting_text: SGSH belongs to the sulfatase family
- term:
    id: GO:0030200
    label: heparan sulfate proteoglycan catabolic process
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: involved_in
  review:
    summary: >-
      Phylogenetically inferred involvement in heparan sulfate catabolism, the specific
      pathway to which SGSH's N-sulfatase activity contributes.
    action: ACCEPT
    reason: >-
      SGSH removes N-sulfate from terminal N-sulfoglucosamine residues during exolytic
      breakdown of the heparan sulfate chain; loss of activity causes lysosomal HS accumulation
      (MPS IIIA). This HS-specific catabolic term is the most informative biological process.
    supported_by:
    - reference_id: PMID:24816101
      supporting_text: catalyses the cleavage of N-linked sulfate groups from the GAGs
        heparan sulfate and heparin
    - reference_id: PMID:7493035
      supporting_text: lysosomal degradation of heparan sulphate
- term:
    id: GO:0006027
    label: glycosaminoglycan catabolic process
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: involved_in
  review:
    summary: >-
      Phylogenetically inferred involvement in glycosaminoglycan catabolism (the parent
      process of heparan sulfate degradation).
    action: ACCEPT
    reason: >-
      Correct but more general than the heparan-sulfate-specific term GO:0030200; both are
      biologically accurate. Retained as a valid grouping annotation for the GAG catabolic role.
    supported_by:
    - reference_id: PMID:24816101
      supporting_text: catalyses the cleavage of N-linked sulfate groups from the GAGs
        heparan sulfate and heparin
- term:
    id: GO:0005764
    label: lysosome
  evidence_type: IEA
  original_reference_id: GO_REF:0000044
  qualifier: located_in
  review:
    summary: >-
      Electronic annotation to lysosome from the UniProt subcellular-location mapping
      (SL-0158), consistent with experimental data.
    action: ACCEPT
    reason: >-
      The SubCell-derived IEA agrees with the curated UniProt location and the IDA evidence;
      correct and non-redundant electronic support for lysosomal localisation.
    supported_by:
    - reference_id: file:human/SGSH/SGSH-uniprot.txt
      supporting_text: "SUBCELLULAR LOCATION: Lysosome"
- term:
    id: GO:0016250
    label: N-sulfoglucosamine sulfohydrolase activity
  evidence_type: IEA
  original_reference_id: GO_REF:0000120
  qualifier: enables
  review:
    summary: >-
      Electronic annotation of the N-sulfoglucosamine sulfohydrolase activity via the
      EC 3.10.1.1 / RHEA:17881 reaction mapping.
    action: ACCEPT
    reason: >-
      The EC/RHEA mapping correctly assigns SGSH's characterized catalytic reaction
      (N-sulfo-D-glucosamine + H2O = D-glucosamine + sulfate); accurate electronic support that
      matches the experimental molecular function.
    supported_by:
    - reference_id: file:human/SGSH/SGSH-uniprot.txt
      supporting_text: N-sulfo-D-glucosamine + H2O = D-glucosamine + sulfate
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:15962010
  qualifier: enables
  review:
    summary: >-
      Bare protein-binding IPI capturing the physical association of SGSH with the
      sulphatase-modifying factor machinery (SUMF1, UniProtKB:Q8NBK3).
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      "protein binding" is uninformative and is not retained as a core function. The underlying
      SGSH-SUMF1 interaction is biologically real and meaningful (SUMF1/FGE generates the
      catalytic formylglycine required for SGSH activity), but a specific molecular function or
      biological process term would be needed to convey it; the bare term is over-annotation.
    supported_by:
    - reference_id: PMID:15962010
      supporting_text: SUMF2 was able to stably associate with IDS and with SGSH alone
        or in a complex with SUMF1
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:33961781
  qualifier: enables
  review:
    summary: >-
      Bare protein-binding IPI from a high-throughput AP-MS interactome (BioPlex), interactor
      SUMF1 (UniProtKB:Q8NBK3).
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      Uninformative molecular function term derived from a proteome-scale interaction screen.
      Consistent with the SGSH-SUMF1 relationship but conveys no specific function; not a core
      annotation.
    supported_by:
    - reference_id: PMID:33961781
      supporting_text: Dual proteome-scale networks reveal cell-specific remodeling of
        the human interactome.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:40205054
  qualifier: enables
  review:
    summary: >-
      Bare protein-binding IPI from a multimodal cell-map interactome resource, interactor
      SUMF1 (UniProtKB:Q8NBK3).
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      Uninformative "protein binding" term from a large-scale mapping study; not retained as a
      core function for the same reasons as the other protein-binding IPIs.
    supported_by:
    - reference_id: PMID:40205054
      supporting_text: Multimodal cell maps as a foundation for structural and functional
        genomics.
- term:
    id: GO:0016250
    label: N-sulfoglucosamine sulfohydrolase activity
  evidence_type: EXP
  original_reference_id: PMID:24816101
  qualifier: enables
  review:
    summary: >-
      Experimentally supported N-sulfoglucosamine sulfohydrolase activity from the SGSH crystal
      structure and accompanying enzymatic characterization.
    action: ACCEPT
    reason: >-
      The structural/biochemical study confirms SGSH as an N-sulfatase that cleaves N-linked
      sulfate from heparan sulfate/heparin via a catalytic formylglycine; this is the core
      molecular function.
    supported_by:
    - reference_id: PMID:24816101
      supporting_text: catalyses the cleavage of N-linked sulfate groups from the GAGs
        heparan sulfate and heparin
    - reference_id: PMID:24816101
      supporting_text: The leading cysteine is post-translationally converted to a formylglycine
        (FGly) residue, which is crucial for the catalytic process
- term:
    id: GO:0043202
    label: lysosomal lumen
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-2263444
  qualifier: located_in
  review:
    summary: >-
      Reactome-asserted lysosomal lumen localisation for the mature SGSH enzyme.
    action: ACCEPT
    reason: >-
      SGSH is a soluble lysosomal enzyme acting in the lysosomal lumen; the more specific
      lumen term is consistent with experimental lysosomal localisation and the site of HS
      degradation.
    supported_by:
    - reference_id: file:human/SGSH/SGSH-uniprot.txt
      supporting_text: "SUBCELLULAR LOCATION: Lysosome"
- term:
    id: GO:0043202
    label: lysosomal lumen
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-9036050
  qualifier: located_in
  review:
    summary: >-
      Reactome-asserted lysosomal lumen localisation (duplicate assertion from a distinct
      Reactome reaction).
    action: ACCEPT
    reason: >-
      Consistent with experimental lysosomal localisation and SGSH's luminal site of action;
      duplicate lumen annotations are acceptable.
    supported_by:
    - reference_id: file:human/SGSH/SGSH-uniprot.txt
      supporting_text: "SUBCELLULAR LOCATION: Lysosome"
- term:
    id: GO:0005764
    label: lysosome
  evidence_type: IDA
  original_reference_id: PMID:15146460
  qualifier: located_in
  review:
    summary: >-
      Direct experimental demonstration of lysosomal localisation of SGSH (immunofluorescence /
      cellular expression studies).
    action: ACCEPT
    reason: >-
      Primary experimental evidence for lysosomal localisation of the mature enzyme; this is a
      core cellular-component annotation for SGSH.
    supported_by:
    - reference_id: PMID:15146460
      supporting_text: autosomal recessive lysosomal
    - reference_id: file:human/SGSH/SGSH-uniprot.txt
      supporting_text: "SUBCELLULAR LOCATION: Lysosome"
- term:
    id: GO:0006027
    label: glycosaminoglycan catabolic process
  evidence_type: IDA
  original_reference_id: PMID:15146460
  qualifier: involved_in
  review:
    summary: >-
      Direct experimental evidence that SGSH participates in glycosaminoglycan (heparan
      sulfate) catabolism; loss of activity causes lysosomal HS accumulation.
    action: ACCEPT
    reason: >-
      SGSH's N-sulfatase step is required for heparan sulfate breakdown; mutant expression
      studies tie loss of activity to the MPS IIIA HS-storage phenotype, supporting the GAG
      catabolic role.
    supported_by:
    - reference_id: PMID:15146460
      supporting_text: storage disease caused by mutations in the N-sulfoglucosamine sulfohydrolase
- term:
    id: GO:0006027
    label: glycosaminoglycan catabolic process
  evidence_type: IDA
  original_reference_id: PMID:7493035
  qualifier: involved_in
  review:
    summary: >-
      Direct experimental evidence (original cloning/characterization) placing SGSH in the
      lysosomal degradation of heparan sulphate, a glycosaminoglycan.
    action: ACCEPT
    reason: >-
      The founding study identifies sulphamidase (EC 3.10.1.1) as an enzyme of lysosomal
      heparan sulphate degradation whose deficiency causes Sanfilippo A; supports the GAG
      catabolic annotation.
    supported_by:
    - reference_id: PMID:7493035
      supporting_text: lysosomal degradation of heparan sulphate
- term:
    id: GO:0016250
    label: N-sulfoglucosamine sulfohydrolase activity
  evidence_type: IDA
  original_reference_id: PMID:15146460
  qualifier: enables
  review:
    summary: >-
      Direct assay of N-sulfoglucosamine sulfohydrolase (sulfamidase) activity of recombinant
      wild-type and mutant SGSH.
    action: ACCEPT
    reason: >-
      Enzyme-activity measurements on expressed SGSH confirm the N-sulfoglucosamine
      sulfohydrolase molecular function; this is the core catalytic activity.
    supported_by:
    - reference_id: PMID:15146460
      supporting_text: enzymatically inactive with the exception of c.318C>A (p.Ser106Arg),
        which
- term:
    id: GO:0016250
    label: N-sulfoglucosamine sulfohydrolase activity
  evidence_type: IDA
  original_reference_id: PMID:7493035
  qualifier: enables
  review:
    summary: >-
      Direct experimental identification of sulphamidase (EC 3.10.1.1) enzymatic activity from
      the cloned SGSH cDNA.
    action: ACCEPT
    reason: >-
      The original characterization established SGSH/sulphamidase enzymatic activity (EC
      3.10.1.1); direct support for the core N-sulfoglucosamine sulfohydrolase molecular function.
    supported_by:
    - reference_id: PMID:7493035
      supporting_text: sulphamidase (EC 3.10.1.1)
- term:
    id: GO:0030200
    label: heparan sulfate proteoglycan catabolic process
  evidence_type: IMP
  original_reference_id: PMID:15146460
  qualifier: involved_in
  review:
    summary: >-
      Mutation-based (IMP) evidence that SGSH function is required for heparan sulfate
      catabolism; pathogenic SGSH variants abolish activity and cause HS accumulation in
      MPS IIIA.
    action: ACCEPT
    reason: >-
      Loss-of-function SGSH mutants are enzymatically inactive and lead to lysosomal heparan
      sulfate storage, directly implicating SGSH in the heparan sulfate catabolic process. This
      HS-specific term is the most informative BP for SGSH.
    supported_by:
    - reference_id: PMID:15146460
      supporting_text: all the mutants were
    - reference_id: PMID:15146460
      supporting_text: storage disease caused by mutations in the N-sulfoglucosamine sulfohydrolase
- term:
    id: GO:0070062
    label: extracellular exosome
  evidence_type: HDA
  original_reference_id: PMID:23533145
  qualifier: located_in
  review:
    summary: >-
      SGSH detected by high-throughput proteomics in exosomes from urinary prostatic
      secretions.
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      Detection in an exosome proteome reflects secretion/vesicular trafficking of a soluble
      lysosomal enzyme rather than its functional compartment. SGSH acts in the lysosomal lumen;
      the exosome location is not a core annotation and is treated as over-annotation.
    supported_by:
    - reference_id: PMID:23533145
      supporting_text: exosomes isolated from expressed prostatic
- term:
    id: GO:0043202
    label: lysosomal lumen
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-1678708
  qualifier: located_in
  review:
    summary: >-
      Reactome-asserted lysosomal lumen localisation (from the HS-GAG degradation pathway).
    action: ACCEPT
    reason: >-
      Consistent with SGSH being a soluble luminal lysosomal enzyme acting in heparan sulfate
      degradation; agrees with the experimental lysosomal localisation.
    supported_by:
    - reference_id: file:human/SGSH/SGSH-uniprot.txt
      supporting_text: "SUBCELLULAR LOCATION: Lysosome"
- term:
    id: GO:0043202
    label: lysosomal lumen
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-2090043
  qualifier: located_in
  review:
    summary: >-
      Reactome-asserted lysosomal lumen localisation (duplicate assertion from a distinct
      Reactome reaction).
    action: ACCEPT
    reason: >-
      Duplicate luminal localisation consistent with experimental lysosomal localisation and
      SGSH's site of action.
    supported_by:
    - reference_id: file:human/SGSH/SGSH-uniprot.txt
      supporting_text: "SUBCELLULAR LOCATION: Lysosome"
core_functions:
- description: >-
    Lysosomal N-sulfoglucosamine sulfohydrolase (heparan N-sulfatase) that hydrolytically
    removes the N-sulfate from terminal N-sulfo-D-glucosamine residues, catalysing a step in
    the exolytic lysosomal degradation of the glycosaminoglycan heparan sulfate. Activity
    depends on a catalytic formylglycine residue and the enzyme acts within the lysosomal lumen.
  molecular_function:
    id: GO:0016250
    label: N-sulfoglucosamine sulfohydrolase activity
  directly_involved_in:
  - id: GO:0030200
    label: heparan sulfate proteoglycan catabolic process
  locations:
  - id: GO:0043202
    label: lysosomal lumen
  supported_by:
  - reference_id: PMID:24816101
    supporting_text: catalyses the cleavage of N-linked sulfate groups from the GAGs
      heparan sulfate and heparin
  - reference_id: PMID:7493035
    supporting_text: lysosomal degradation of heparan sulphate
  - reference_id: file:human/SGSH/SGSH-uniprot.txt
    supporting_text: Catalyzes a step in lysosomal heparan sulfate degradation