id: P07741
gene_symbol: APRT
product_type: PROTEIN
status: INITIALIZED
taxon:
  id: NCBITaxon:9606
  label: Homo sapiens
description: Adenine phosphoribosyltransferase (APRT; EC 2.4.2.7) is the cytosolic
  enzyme of the purine salvage pathway that catalyzes the transfer of the phosphoribosyl
  group of 5-phospho-alpha-D-ribose 1-diphosphate (PRPP) to adenine, producing AMP
  and diphosphate. This single-step reaction recycles free adenine - notably the adenine
  released as a byproduct of polyamine biosynthesis, as well as adenine of dietary
  origin - into the adenine nucleotide pool at lower energetic cost than de novo synthesis.
  APRT is a homodimer belonging to the type I purine/pyrimidine phosphoribosyltransferase
  family and, like other type I PRTases, uses a magnesium-PRPP complex; it is expressed
  ubiquitously and acts in the cytosol. Loss of APRT function causes adenine phosphoribosyltransferase
  deficiency (APRTD), an autosomal recessive disorder in which unsalvaged adenine is
  instead oxidized by xanthine dehydrogenase to the highly insoluble 2,8-dihydroxyadenine
  (2,8-DHA); precipitation of 2,8-DHA in the urinary tract and renal parenchyma produces
  2,8-DHA nephrolithiasis, crystalline nephropathy, and progressive renal failure.
alternative_products:
- name: '1'
  id: P07741-1
- name: '2'
  id: P07741-2
  sequence_note: VSP_045705
existing_annotations:
- term:
    id: GO:0003999
    label: adenine phosphoribosyltransferase activity
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: enables
  review:
    summary: Core molecular function of APRT - transfer of the phosphoribosyl group
      of PRPP to adenine to form AMP (EC 2.4.2.7). Phylogenetically inferred and consistent
      with direct enzymatic and structural evidence for the human enzyme.
    action: ACCEPT
    reason: This is the defining catalytic activity of APRT, supported by the crystal
      structure with AMP product and measured kinetics for the human enzyme, and conserved
      across the phosphoribosyltransferase family used for the IBA inference.
    supported_by:
    - reference_id: PMID:15196008
      supporting_text: In mammals, adenine phosphoribosyltransferase (APRT, EC 2.4.2.7)
        is present in all tissues and provides the only known mechanism for the metabolic
        salvage of adenine
- term:
    id: GO:0005737
    label: cytoplasm
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: is_active_in
  review:
    summary: APRT is a soluble cytoplasmic/cytosolic enzyme; phylogenetic inference
      of a cytoplasmic location is correct but less precise than the cytosol annotations.
    action: ACCEPT
    reason: Consistent with the UniProt subcellular location (Cytoplasm) and with
      the more specific cytosol annotations from HPA and Ensembl. Correct as a broader
      location term.
    supported_by:
    - reference_id: file:human/APRT/APRT-uniprot.txt
      supporting_text: "SUBCELLULAR LOCATION: Cytoplasm."
- term:
    id: GO:0006168
    label: adenine salvage
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: involved_in
  review:
    summary: APRT is the enzyme that salvages free adenine by converting it to AMP;
      adenine salvage is a core biological process for this gene.
    action: ACCEPT
    reason: Directly matches the established function - APRT provides the salvage route
      for adenine arising from polyamine biosynthesis and diet. Well supported experimentally
      and by phylogeny.
    supported_by:
    - reference_id: PMID:15196008
      supporting_text: provides the only known mechanism for the metabolic salvage
        of adenine resulting from the polyamine biosynthesis pathway or from dietary
        sources
- term:
    id: GO:0044209
    label: AMP salvage
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: involved_in
  review:
    summary: The product of the APRT reaction is AMP; the enzyme constitutes the AMP-from-adenine
      salvage step. Core biological process.
    action: ACCEPT
    reason: UniProt records the pathway explicitly as AMP biosynthesis via salvage
      pathway (AMP from adenine, step 1/1), matching this term. Consistent with the
      IBA inference.
    supported_by:
    - reference_id: file:human/APRT/APRT-uniprot.txt
      supporting_text: "PATHWAY: Purine metabolism; AMP biosynthesis via salvage pathway;
        AMP from adenine: step 1/1."
- term:
    id: GO:0002055
    label: adenine binding
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: enables
  review:
    summary: Adenine is the small-molecule substrate of APRT; binding of adenine is
      a mechanistic component of the catalytic function.
    action: ACCEPT
    reason: Supported by the human structure/kinetics (KM for adenine ~4 uM) and consistent
      with the enzyme's substrate specificity. A valid, informative substrate-binding
      term underpinning the catalytic activity.
    supported_by:
    - reference_id: file:human/APRT/APRT-uniprot.txt
      supporting_text: KM=4 uM for adenine
- term:
    id: GO:0016208
    label: AMP binding
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: enables
  review:
    summary: AMP is the reaction product of APRT and is co-crystallized in the active
      site; product binding is a mechanistic component of catalysis.
    action: ACCEPT
    reason: The human enzyme was crystallized in complex with AMP, directly demonstrating
      AMP binding in the active-site pocket. Consistent with the IBA inference.
    supported_by:
    - reference_id: PMID:15196008
      supporting_text: the recombinant human APRT was crystallized in complex with
        adenosine 5'-monophosphate (AMP)
- term:
    id: GO:0003999
    label: adenine phosphoribosyltransferase activity
  evidence_type: IEA
  original_reference_id: GO_REF:0000120
  qualifier: enables
  review:
    summary: Electronic assertion (UniProt combined pipeline; RHEA:16609 / EC 2.4.2.7)
      of the core catalytic activity, in agreement with the experimental annotation.
    action: ACCEPT
    reason: Correct and specific; duplicates the experimentally supported core molecular
      function. Retained as a valid electronic corroboration.
    supported_by:
    - reference_id: file:human/APRT/APRT-uniprot.txt
      supporting_text: "EC=2.4.2.7 {ECO:0000269|PubMed:15196008}"
- term:
    id: GO:0005737
    label: cytoplasm
  evidence_type: IEA
  original_reference_id: GO_REF:0000120
  qualifier: located_in
  review:
    summary: Electronic assertion of cytoplasmic localization (UniProt-SubCell SL-0086),
      consistent with the curated subcellular location.
    action: ACCEPT
    reason: Matches the UniProt cytoplasm subcellular location and the more specific
      cytosol annotations. Correct broader location.
    supported_by:
    - reference_id: file:human/APRT/APRT-uniprot.txt
      supporting_text: "SUBCELLULAR LOCATION: Cytoplasm."
- term:
    id: GO:0006168
    label: adenine salvage
  evidence_type: IEA
  original_reference_id: GO_REF:0000002
  qualifier: involved_in
  review:
    summary: InterPro2GO electronic assertion (IPR005764, adenine phosphoribosyltransferase)
      of adenine salvage, matching the core biological process.
    action: ACCEPT
    reason: Correct process term derived from the family-specific InterPro signature;
      duplicates the experimentally/phylogenetically supported adenine salvage role.
    supported_by:
    - reference_id: PMID:15196008
      supporting_text: provides the only known mechanism for the metabolic salvage
        of adenine
- term:
    id: GO:1901363
    label: heterocyclic compound binding
  evidence_type: IEA
  original_reference_id: GO_REF:0000117
  qualifier: enables
  review:
    summary: Very general ARBA-derived binding term. APRT does bind heterocyclic compounds
      (adenine, AMP), but this high-level term is uninformative relative to the specific
      adenine binding / AMP binding annotations already present.
    action: MARK_AS_OVER_ANNOTATED
    reason: The term is not incorrect (adenine and AMP are heterocyclic), but it is
      an overly generic parent term that adds no functional information beyond the
      specific substrate/product binding terms; per curation guidelines uninformative
      high-level binding terms should not be treated as representing gene function.
    supported_by:
    - reference_id: file:human/APRT/APRT-uniprot.txt
      supporting_text: KM=4 uM for adenine
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:32296183
  qualifier: enables
  review:
    summary: High-throughput binary interactome (HuRI) IPI annotation; the interaction
      partner is TTC19 (UniProtKB:Q6DKK2). "protein binding" is an uninformative molecular
      function term and no specific adaptor/complex role for APRT is established.
    action: MARK_AS_OVER_ANNOTATED
    reason: This is an experimentally derived interaction, so it is retained rather
      than removed, but bare "protein binding" conveys no specific molecular function
      and the TTC19 interaction has no established functional consequence for adenine
      salvage; it should not be treated as a core function.
    supported_by:
    - reference_id: PMID:32296183
      supporting_text: reference interactome map of human binary protein interactions
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:32814053
  qualifier: enables
  review:
    summary: Yeast two-hybrid interactome (neurodegenerative-disease network) IPI annotation;
      the partner is SPRED1 (UniProtKB:Q7Z699). Bare "protein binding" is uninformative
      and no specific functional role is defined.
    action: MARK_AS_OVER_ANNOTATED
    reason: Retained as an experimental interaction but the generic "protein binding"
      term adds no functional specificity for APRT and the interaction has no established
      biological consequence for its salvage function; not a core function.
    supported_by:
    - reference_id: PMID:32814053
      supporting_text: systematic yeast two-hybrid interaction screening
- term:
    id: GO:0002055
    label: adenine binding
  evidence_type: IEA
  original_reference_id: GO_REF:0000107
  qualifier: enables
  review:
    summary: Ensembl-Compara ortholog-transfer (from mouse Aprt, P08030) of adenine
      binding, matching the enzyme's substrate.
    action: ACCEPT
    reason: Correct substrate-binding term consistent with the IBA/experimental adenine
      binding evidence; duplicates a valid mechanistic MF component.
    supported_by:
    - reference_id: file:human/APRT/APRT-uniprot.txt
      supporting_text: KM=4 uM for adenine
- term:
    id: GO:0005829
    label: cytosol
  evidence_type: IEA
  original_reference_id: GO_REF:0000107
  qualifier: is_active_in
  review:
    summary: Ensembl-Compara ortholog-transfer of cytosolic localization; APRT is
      a soluble cytosolic enzyme.
    action: ACCEPT
    reason: Consistent with the IDA (HPA) cytosol annotation and the UniProt cytoplasmic
      location. Correct and specific.
    supported_by:
    - reference_id: file:human/APRT/APRT-uniprot.txt
      supporting_text: "SUBCELLULAR LOCATION: Cytoplasm."
- term:
    id: GO:0032263
    label: GMP salvage
  evidence_type: IEA
  original_reference_id: GO_REF:0000107
  qualifier: involved_in
  review:
    summary: Ensembl-Compara ortholog-transferred process annotation. APRT is specific
      for adenine and produces AMP; it does not act on guanine and has no role in GMP
      salvage (that is the function of HGPRT/HPRT1).
    action: REMOVE
    reason: Incorrect electronic (IEA) inference. The APRT reaction (adenine + PRPP
      -> AMP) does not generate or salvage GMP; GMP/guanine salvage is carried out
      by hypoxanthine-guanine phosphoribosyltransferase, a different enzyme. This appears
      to be an over-broad process transfer across the PRTase family and is biologically
      wrong for APRT.
    supported_by:
    - reference_id: file:human/APRT/APRT-uniprot.txt
      supporting_text: "PATHWAY: Purine metabolism; AMP biosynthesis via salvage pathway;
        AMP from adenine: step 1/1."
- term:
    id: GO:0032264
    label: IMP salvage
  evidence_type: IEA
  original_reference_id: GO_REF:0000107
  qualifier: involved_in
  review:
    summary: Ensembl-Compara ortholog-transferred process annotation. APRT is adenine-specific
      and produces AMP; it does not act on hypoxanthine and has no role in IMP salvage
      (that is the function of HGPRT/HPRT1).
    action: REMOVE
    reason: Incorrect electronic (IEA) inference. The APRT reaction produces AMP from
      adenine, not IMP from hypoxanthine; IMP/hypoxanthine salvage is carried out by
      hypoxanthine-guanine phosphoribosyltransferase. Biologically wrong for APRT and
      an over-broad family-level process transfer.
    supported_by:
    - reference_id: file:human/APRT/APRT-uniprot.txt
      supporting_text: "PATHWAY: Purine metabolism; AMP biosynthesis via salvage pathway;
        AMP from adenine: step 1/1."
- term:
    id: GO:0044209
    label: AMP salvage
  evidence_type: IEA
  original_reference_id: GO_REF:0000120
  qualifier: involved_in
  review:
    summary: UniProt combined-pipeline electronic assertion (UniPathway UPA00588) of
      AMP salvage, matching the core biological process.
    action: ACCEPT
    reason: Correct and specific; duplicates the phylogenetically supported AMP salvage
      role and agrees with the UniProt AMP-from-adenine salvage pathway assignment.
    supported_by:
    - reference_id: file:human/APRT/APRT-uniprot.txt
      supporting_text: "PATHWAY: Purine metabolism; AMP biosynthesis via salvage pathway;
        AMP from adenine: step 1/1."
- term:
    id: GO:0005829
    label: cytosol
  evidence_type: IDA
  original_reference_id: GO_REF:0000052
  qualifier: located_in
  review:
    summary: Direct immunofluorescence localization (Human Protein Atlas) to the cytosol,
      the site of APRT catalytic activity.
    action: ACCEPT
    reason: Experimental (IDA) support for the correct, specific subcellular location
      of this soluble salvage enzyme; consistent with UniProt.
    supported_by:
    - reference_id: file:human/APRT/APRT-uniprot.txt
      supporting_text: "SUBCELLULAR LOCATION: Cytoplasm."
- term:
    id: GO:0003999
    label: adenine phosphoribosyltransferase activity
  evidence_type: IDA
  original_reference_id: PMID:15196008
  qualifier: enables
  review:
    summary: Direct experimental determination of the catalytic activity of the recombinant
      human enzyme, including the crystal structure and kinetic parameters; this is
      the core molecular function.
    action: ACCEPT
    reason: Strongest evidence for the defining function of APRT - direct assay of
      adenine phosphoribosyltransferase (EC 2.4.2.7) activity on the human protein.
    supported_by:
    - reference_id: PMID:15196008
      supporting_text: In mammals, adenine phosphoribosyltransferase (APRT, EC 2.4.2.7)
        is present in all tissues and provides the only known mechanism for the metabolic
        salvage of adenine
- term:
    id: GO:0005829
    label: cytosol
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-9734193
  qualifier: located_in
  review:
    summary: Reactome traceable assertion (Defective APRT does not convert adenine
      to AMP) placing APRT in the cytosol, the site of the salvage reaction.
    action: ACCEPT
    reason: Correct and specific location, consistent with the experimental (IDA) cytosol
      annotation and UniProt.
    supported_by:
    - reference_id: file:human/APRT/APRT-uniprot.txt
      supporting_text: "SUBCELLULAR LOCATION: Cytoplasm."
- term:
    id: GO:0005576
    label: extracellular region
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-6798748
  qualifier: located_in
  review:
    summary: Reactome annotation derived from the neutrophil-degranulation pathway
      (Exocytosis of secretory granule lumen proteins). APRT is detected in neutrophil
      granule proteomes but this is not its site of catalytic function.
    action: MARK_AS_OVER_ANNOTATED
    reason: APRT is a cytosolic salvage enzyme with no signal peptide and no secretory
      function; its appearance in the extracellular region reflects inclusion in a
      large neutrophil-degranulation proteome pathway rather than a genuine functional
      extracellular localization. Retained (not a demonstrably wrong IEA) but flagged
      as over-annotation.
    supported_by:
    - reference_id: file:human/APRT/APRT-uniprot.txt
      supporting_text: "SUBCELLULAR LOCATION: Cytoplasm."
- term:
    id: GO:0034774
    label: secretory granule lumen
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-6798748
  qualifier: located_in
  review:
    summary: Reactome annotation from the neutrophil-degranulation pathway. Reflects
      detection of APRT in neutrophil granule preparations, not a bona fide functional
      localization of this cytosolic enzyme.
    action: MARK_AS_OVER_ANNOTATED
    reason: As with the extracellular-region annotation, this is a consequence of APRT
      being catalogued in a neutrophil secretory-granule proteome pathway. APRT is
      a soluble cytosolic protein without a secretory route; not a core location.
    supported_by:
    - reference_id: file:human/APRT/APRT-uniprot.txt
      supporting_text: "SUBCELLULAR LOCATION: Cytoplasm."
- term:
    id: GO:0070062
    label: extracellular exosome
  evidence_type: HDA
  original_reference_id: PMID:23533145
  qualifier: located_in
  review:
    summary: High-throughput proteomic detection of APRT in urinary/prostatic exosome
      preparations. A common finding for abundant cytosolic proteins; not a functional
      localization.
    action: MARK_AS_OVER_ANNOTATED
    reason: Detection in a large exosome proteome (~900 proteins) reflects the well-known
      presence of abundant cytosolic enzymes in extracellular vesicle preparations
      rather than a specific functional role of APRT in exosomes. Retained as experimental
      but flagged as over-annotation.
    supported_by:
    - reference_id: PMID:23533145
      supporting_text: exosome preparations were characterized by a shotgun proteomics
        procedure
- term:
    id: GO:0070062
    label: extracellular exosome
  evidence_type: HDA
  original_reference_id: PMID:19056867
  qualifier: located_in
  review:
    summary: High-throughput proteomic detection of APRT among 1132 proteins profiled
      in human urinary exosomes; a mass-spectrometry catalogue rather than evidence
      of functional exosomal localization.
    action: MARK_AS_OVER_ANNOTATED
    reason: The same over-annotation pattern - abundant cytosolic APRT is captured
      in large-scale urinary exosome proteomes. Not a core or functional location
      for this salvage enzyme.
    supported_by:
    - reference_id: PMID:19056867
      supporting_text: we used LC-MS/MS to profile the proteome of human urinary exosomes
- term:
    id: GO:0070062
    label: extracellular exosome
  evidence_type: HDA
  original_reference_id: PMID:20458337
  qualifier: located_in
  review:
    summary: High-throughput proteomic detection of APRT in the total proteome of
      purified B-cell-derived exosomes (539 proteins); a proteomic catalogue, not
      functional localization.
    action: MARK_AS_OVER_ANNOTATED
    reason: Third instance of the exosome-proteome over-annotation pattern. APRT is
      an abundant cytosolic enzyme routinely recovered in extracellular-vesicle preparations;
      this is not a core location.
    supported_by:
    - reference_id: PMID:20458337
      supporting_text: total proteome of highly purified B cell-derived exosomes
- term:
    id: GO:0005829
    label: cytosol
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-74213
  qualifier: located_in
  review:
    summary: Reactome traceable assertion (APRT catalyzes the conversion of adenine
      to AMP) placing the reaction in the cytosol, the correct functional location.
    action: ACCEPT
    reason: Correct and specific; consistent with the experimental cytosol annotation
      and UniProt cytoplasmic location, and it correctly assigns the catalytic reaction
      to the cytosol.
    supported_by:
    - reference_id: file:human/APRT/APRT-uniprot.txt
      supporting_text: "SUBCELLULAR LOCATION: Cytoplasm."
- term:
    id: GO:0016208
    label: AMP binding
  evidence_type: IDA
  original_reference_id: PMID:15196008
  qualifier: enables
  review:
    summary: Direct structural evidence of AMP binding - the human enzyme was crystallized
      in complex with its AMP product occupying the active-site pocket.
    action: ACCEPT
    reason: Experimental (IDA) support for product binding, a mechanistic component
      of the catalytic function; the co-crystal structure with AMP directly demonstrates
      binding.
    supported_by:
    - reference_id: PMID:15196008
      supporting_text: the active site pocket opens slightly to accommodate the AMP
        product
- term:
    id: GO:0005737
    label: cytoplasm
  evidence_type: TAS
  original_reference_id: PMID:16130169
  qualifier: located_in
  review:
    summary: Cytoplasmic localization asserted from a HUVEC proteomic study. Consistent
      with the soluble cytoplasmic nature of APRT, though less specific than the cytosol
      annotations.
    action: ACCEPT
    reason: Correct broader location term, in agreement with UniProt and the cytosol
      annotations. The supporting proteomic study catalogued cytoplasmic endothelial
      proteins including APRT.
    supported_by:
    - reference_id: PMID:16130169
      supporting_text: The overall functional characterization of the 162 identified
        proteins
- term:
    id: GO:0003999
    label: adenine phosphoribosyltransferase activity
  evidence_type: TAS
  original_reference_id: PMID:3531209
  qualifier: enables
  review:
    summary: Traceable assertion of the core adenine phosphoribosyltransferase function,
      from the paper that established the complete amino acid sequence of the human
      erythrocyte enzyme.
    action: ACCEPT
    reason: Supports the defining catalytic function of APRT; the reference characterizes
      the human enzyme and its family relationship to other phosphoribosyltransferases.
    supported_by:
    - reference_id: PMID:3531209
      supporting_text: Human adenine phosphoribosyltransferase has sequence homology
        with xanthine-guanine phosphoribosyltransferase from Escherichia coli
core_functions:
- description: Catalyzes the salvage of free adenine by transferring the phosphoribosyl
    group of PRPP to adenine, producing AMP and diphosphate (EC 2.4.2.7), in the cytosol.
  molecular_function:
    id: GO:0003999
    label: adenine phosphoribosyltransferase activity
  directly_involved_in:
  - id: GO:0006168
    label: adenine salvage
  locations:
  - id: GO:0005829
    label: cytosol
  supported_by:
  - reference_id: PMID:15196008
    supporting_text: In mammals, adenine phosphoribosyltransferase (APRT, EC 2.4.2.7)
      is present in all tissues and provides the only known mechanism for the metabolic
      salvage of adenine
- description: Recycles adenine into the adenine nucleotide pool by producing AMP,
    constituting the AMP-from-adenine salvage step of purine metabolism.
  molecular_function:
    id: GO:0003999
    label: adenine phosphoribosyltransferase activity
  directly_involved_in:
  - id: GO:0044209
    label: AMP salvage
  locations:
  - id: GO:0005829
    label: cytosol
  supported_by:
  - reference_id: file:human/APRT/APRT-uniprot.txt
    supporting_text: "PATHWAY: Purine metabolism; AMP biosynthesis via salvage pathway;
      AMP from adenine: step 1/1."
references:
- id: GO_REF:0000002
  title: Gene Ontology annotation through association of InterPro records with GO
    terms
  findings: []
- id: GO_REF:0000033
  title: Annotation inferences using phylogenetic trees
  findings: []
- id: GO_REF:0000052
  title: Gene Ontology annotation based on curation of immunofluorescence data
  findings: []
- id: GO_REF:0000107
  title: Automatic transfer of experimentally verified manual GO annotation data to
    orthologs using Ensembl Compara
  findings: []
- id: GO_REF:0000117
  title: Electronic Gene Ontology annotations created by ARBA machine learning models
  findings: []
- id: GO_REF:0000120
  title: Combined Automated Annotation using Multiple IEA Methods
  findings: []
- id: PMID:15196008
  title: Three-dimensional structure of human adenine phosphoribosyltransferase and
    its relation to DHA-urolithiasis.
  findings:
  - statement: The recombinant human APRT was crystallized in complex with AMP, revealing
      a type I PRTase fold and providing the structural basis for DHA-urolithiasis-causing
      mutations. APRT is the only route for salvage of adenine from polyamine biosynthesis
      or diet.
    supporting_text: In mammals, adenine phosphoribosyltransferase (APRT, EC 2.4.2.7)
      is present in all tissues and provides the only known mechanism for the metabolic
      salvage of adenine resulting from the polyamine biosynthesis pathway or from
      dietary sources.
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: PubMed-verified; the crystallographic and kinetic study of the human
      enzyme that directly establishes the catalytic activity, AMP binding, and disease
      relevance. Abstract-only in cache but sufficient to anchor the core claims.
- id: PMID:16130169
  title: Proteomics of human umbilical vein endothelial cells applied to etoposide-induced
    apoptosis.
  findings: []
  reference_review:
    relevance: LOW
    correctness: VERIFIED
    review_notes: Large-scale HUVEC proteomic study; APRT is among the catalogued
      cytoplasmic proteins. Source of the cytoplasm TAS annotation; contextual only.
- id: PMID:19056867
  title: Large-scale proteomics and phosphoproteomics of urinary exosomes.
  findings: []
  reference_review:
    relevance: LOW
    correctness: VERIFIED
    review_notes: Urinary exosome proteome (1132 proteins); APRT detected as an abundant
      cytosolic protein. Supports an over-annotated exosome localization, not function.
- id: PMID:20458337
  title: MHC class II-associated proteins in B-cell exosomes and potential functional
    implications for exosome biogenesis.
  findings: []
  reference_review:
    relevance: LOW
    correctness: VERIFIED
    review_notes: B-cell exosome proteome (539 proteins); APRT is a background cytosolic
      constituent. Basis for an over-annotated exosome localization.
- 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: EPS-urine exosome proteome (~900 proteins); APRT captured as an
      abundant cytosolic protein. Over-annotated exosome localization, not function.
- id: PMID:32296183
  title: A reference map of the human binary protein interactome.
  findings: []
  reference_review:
    relevance: LOW
    correctness: VERIFIED
    review_notes: HuRI high-throughput binary interactome; source of an uninformative
      protein binding IPI (partner TTC19). No functional consequence established for
      APRT.
- id: PMID:32814053
  title: Interactome Mapping Provides a Network of Neurodegenerative Disease Proteins
    and Uncovers Widespread Protein Aggregation in Affected Brains.
  findings: []
  reference_review:
    relevance: LOW
    correctness: VERIFIED
    review_notes: Y2H neurodegenerative-disease interactome; source of an uninformative
      protein binding IPI (partner SPRED1). No functional consequence established for
      APRT.
- id: PMID:3531209
  title: Human adenine phosphoribosyltransferase. Complete amino acid sequence of
    the erythrocyte enzyme.
  findings:
  - statement: Established the complete 179-residue amino acid sequence of human erythrocyte
      APRT, showing homology to E. coli xanthine-guanine phosphoribosyltransferase
      and an acetylated N-terminus.
    supporting_text: Human adenine phosphoribosyltransferase has sequence homology
      with xanthine-guanine phosphoribosyltransferase from Escherichia coli
  reference_review:
    relevance: MEDIUM
    correctness: VERIFIED
    review_notes: Foundational protein-sequence paper for human APRT; supports the
      TAS molecular-function annotation and family membership.
- id: Reactome:R-HSA-6798748
  title: Exocytosis of secretory granule lumen proteins
  findings: []
- id: Reactome:R-HSA-74213
  title: APRT catalyzes the conversion of adenine to AMP
  findings: []
- id: Reactome:R-HSA-9734193
  title: Defective APRT does not convert adenine to AMP
  findings: []