id: P49064
gene_symbol: ALB
product_type: PROTEIN
status: DRAFT
taxon:
  id: NCBITaxon:9685
  label: Felis catus
description: >-
  Serum albumin of the domestic cat, the allergen Fel d 2. The most abundant
  plasma protein and the archetypal multi-ligand transport protein of the
  ALB/AFP/VDB family: it binds and carries water, metal ions (zinc, calcium,
  magnesium, sodium, potassium), fatty acids, hormones, bilirubin and many drugs,
  and its principal physiological role is regulation of the colloidal osmotic
  pressure of blood. It is the major plasma zinc transporter and a major calcium/
  magnesium transporter, and it sequesters the bacterial siderophore enterobactin,
  contributing to nutritional immunity. As an allergen, Fel d 2 is a minor,
  cross-reactive component responsible for cross-sensitization between mammalian
  albumins (e.g. pork-cat syndrome).
existing_annotations:
- term:
    id: GO:0031667
    label: response to nutrient levels
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: involved_in
  review:
    summary: Broad physiological-response term reflecting albumin's role in nutrient/metabolite transport and starvation responses.
    action: KEEP_AS_NON_CORE
    reason: Generic process association; not a core, distinguishing function of albumin.
- term:
    id: GO:1903981
    label: enterobactin binding
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: enables
  review:
    summary: >-
      Albumin binds the bacterial siderophore enterobactin and inhibits
      enterobactin-mediated iron uptake by bacteria, a documented function.
    action: ACCEPT
    reason: Supported by the curated UniProt function describing enterobactin binding.
    supported_by:
    - reference_id: file:FELCA/ALB/ALB-uniprot.txt
      supporting_text: enterobactin and inhibits enterobactin-mediated iron uptake of E.coli
- term:
    id: GO:0005576
    label: extracellular region
  evidence_type: IEA
  original_reference_id: GO_REF:0000120
  qualifier: located_in
  review:
    summary: Albumin is a secreted plasma protein; extracellular localization is correct and central.
    action: ACCEPT
    reason: Albumin functions in blood plasma (extracellular region).
- term:
    id: GO:0005737
    label: cytoplasm
  evidence_type: IEA
  original_reference_id: GO_REF:0000118
  qualifier: located_in
  review:
    summary: >-
      Albumin is a secreted protein; any cytoplasmic signal reflects its
      biosynthetic route through the hepatocyte, not its functional compartment.
    action: KEEP_AS_NON_CORE
    reason: Biosynthetic/transit localization; the functional compartment is extracellular plasma.
- term:
    id: GO:0036094
    label: small molecule binding
  evidence_type: IEA
  original_reference_id: GO_REF:0000118
  qualifier: enables
  review:
    summary: Generic parent term; albumin's specific ligand-binding activities (fatty acid, metal ion, enterobactin) are the informative annotations.
    action: MARK_AS_OVER_ANNOTATED
    reason: Uninformative broad parent of the specific binding functions.
- term:
    id: GO:0072562
    label: blood microparticle
  evidence_type: IEA
  original_reference_id: GO_REF:0000118
  qualifier: located_in
  review:
    summary: Albumin is a common constituent of blood microparticles, consistent with its high plasma abundance.
    action: KEEP_AS_NON_CORE
    reason: Plausible plasma-derived localization; not a distinguishing functional compartment.
- term:
    id: GO:1903981
    label: enterobactin binding
  evidence_type: IEA
  original_reference_id: GO_REF:0000118
  qualifier: enables
  review:
    summary: Electronic duplicate of the enterobactin-binding function.
    action: ACCEPT
    reason: Consistent with the curated enterobactin-binding/nutritional-immunity function.
    supported_by:
    - reference_id: file:FELCA/ALB/ALB-uniprot.txt
      supporting_text: enterobactin and inhibits enterobactin-mediated iron uptake of E.coli
- term:
    id: GO:0051902
    label: negative regulation of mitochondrial depolarization
  evidence_type: ISS
  original_reference_id: GO_REF:0000024
  qualifier: involved_in
  review:
    summary: Similarity-transferred cytoprotective process; downstream/indirect for a plasma carrier protein.
    action: KEEP_AS_NON_CORE
    reason: Indirect, similarity-based association; not a core albumin function.
- term:
    id: GO:0072732
    label: cellular response to calcium ion starvation
  evidence_type: ISS
  original_reference_id: GO_REF:0000024
  qualifier: involved_in
  review:
    summary: Reflects albumin's role as a plasma calcium reservoir/transporter; broad process term.
    action: KEEP_AS_NON_CORE
    reason: Similarity-based process association tied to calcium transport; non-core.
- term:
    id: GO:1903981
    label: enterobactin binding
  evidence_type: ISS
  original_reference_id: GO_REF:0000024
  qualifier: enables
  review:
    summary: Similarity-transferred enterobactin binding, agreeing with the curated function.
    action: ACCEPT
    reason: Consistent with documented enterobactin binding.
    supported_by:
    - reference_id: file:FELCA/ALB/ALB-uniprot.txt
      supporting_text: enterobactin and inhibits enterobactin-mediated iron uptake of E.coli
- term:
    id: GO:0003677
    label: DNA binding
  evidence_type: ISS
  original_reference_id: GO_REF:0000024
  qualifier: enables
  review:
    summary: >-
      Albumin is not a bona fide sequence-specific DNA-binding protein; any DNA
      association is non-specific and reflects its promiscuous, highly abundant
      ligand-binding surface rather than a genuine molecular function.
    action: MARK_AS_OVER_ANNOTATED
    reason: Misleading functional assignment for a plasma carrier protein; likely an artifact of promiscuous binding propagated by similarity.
- term:
    id: GO:0005504
    label: fatty acid binding
  evidence_type: ISS
  original_reference_id: GO_REF:0000024
  qualifier: enables
  review:
    summary: >-
      Fatty acid binding and transport is one of albumin's best-characterized,
      core molecular functions.
    action: ACCEPT
    reason: Classic, well-established albumin function; central to its role as a plasma lipid carrier.
    supported_by:
    - reference_id: file:FELCA/ALB/ALB-uniprot.txt
      supporting_text: Binds water, Ca(2+), Na(+), K(+), fatty acids, hormones,
- term:
    id: GO:0009267
    label: cellular response to starvation
  evidence_type: ISS
  original_reference_id: GO_REF:0000024
  qualifier: involved_in
  review:
    summary: Broad process term linked to albumin's role in nutrient/metabolite supply.
    action: KEEP_AS_NON_CORE
    reason: Generic, similarity-based process; non-core.
- term:
    id: GO:0015643
    label: toxic substance binding
  evidence_type: ISS
  original_reference_id: GO_REF:0000024
  qualifier: enables
  review:
    summary: >-
      Albumin binds and carries many drugs, toxins and metabolites; toxic-substance
      binding reflects this promiscuous carrier role.
    action: KEEP_AS_NON_CORE
    reason: Real but secondary facet of albumin's general small-molecule carrier function.
    supported_by:
    - reference_id: file:FELCA/ALB/ALB-uniprot.txt
      supporting_text: bilirubin and drugs. Its main function is the regulation of the
- term:
    id: GO:0019825
    label: oxygen binding
  evidence_type: ISS
  original_reference_id: GO_REF:0000024
  qualifier: contributes_to
  review:
    summary: Similarity-transferred oxygen binding; a minor facet relative to albumin's principal ligand-carrier roles.
    action: KEEP_AS_NON_CORE
    reason: Minor/secondary binding activity; non-core.
- term:
    id: GO:0030170
    label: pyridoxal phosphate binding
  evidence_type: ISS
  original_reference_id: GO_REF:0000024
  qualifier: enables
  review:
    summary: Albumin binds pyridoxal 5'-phosphate (vitamin B6) in plasma; one of its many small-molecule ligands.
    action: KEEP_AS_NON_CORE
    reason: Specific but secondary ligand-binding facet of the general carrier function.
- term:
    id: GO:0032991
    label: protein-containing complex
  evidence_type: ISS
  original_reference_id: GO_REF:0000024
  qualifier: part_of
  review:
    summary: Uninformative, top-level cellular-component term.
    action: MARK_AS_OVER_ANNOTATED
    reason: Generic root-level term carrying no specific information.
core_functions:
- description: >-
    Major plasma multi-ligand transport protein: binds and carries fatty acids,
    metal ions (zinc, calcium, magnesium), hormones, bilirubin and drugs in blood,
    and through its high abundance regulates the colloidal osmotic pressure of
    blood. Fatty acid binding is the prototypical molecular activity.
  molecular_function:
    id: GO:0005504
    label: fatty acid binding
  supported_by:
  - reference_id: file:FELCA/ALB/ALB-uniprot.txt
    supporting_text: Binds water, Ca(2+), Na(+), K(+), fatty acids, hormones,
  - reference_id: file:FELCA/ALB/ALB-uniprot.txt
    supporting_text: colloidal osmotic pressure of blood.
  locations:
  - id: GO:0005576
    label: extracellular region
- description: >-
    Sequesters the bacterial siderophore enterobactin in plasma, inhibiting
    enterobactin-mediated iron acquisition by enteric bacteria and thereby
    contributing to nutritional immunity.
  molecular_function:
    id: GO:1903981
    label: enterobactin binding
  supported_by:
  - reference_id: file:FELCA/ALB/ALB-uniprot.txt
    supporting_text: enterobactin and inhibits enterobactin-mediated iron uptake of E.coli
  locations:
  - id: GO:0005576
    label: extracellular region
proposed_new_terms: []
suggested_questions:
- question: >-
    Does cat serum albumin share the human albumin zinc/calcium "crosstalk" site
    (Asp-273 equivalent), and how does its metal-transport stoichiometry compare?
  experts: []
suggested_experiments:
- hypothesis: Fel d 2 (cat albumin) reproduces the canonical mammalian albumin fatty-acid and metal-ion binding profile.
  description: >-
    Measure fatty-acid and Zn2+/Ca2+ binding of purified cat albumin by ITC and
    compare site occupancy to human serum albumin via competition assays and
    structural modeling.
  experiment_type: biophysical binding assay
references:
- id: GO_REF:0000024
  title: Manual transfer of experimentally-verified manual GO annotation data to orthologs by curator judgment of sequence similarity
  findings: []
- id: GO_REF:0000033
  title: Annotation inferences using phylogenetic trees
  findings: []
- id: GO_REF:0000118
  title: TreeGrafter-generated GO annotations
  findings: []
- id: GO_REF:0000120
  title: Combined Automated Annotation using Multiple IEA Methods
  findings: []
- id: file:FELCA/ALB/ALB-uniprot.txt
  title: UniProt entry P49064 (ALBU_FELCA), Serum albumin / Fel d 2
  findings:
  - statement: >-
      Cat serum albumin binds water, metal ions, fatty acids, hormones, bilirubin
      and drugs; its main role is regulation of blood colloidal osmotic pressure,
      and it binds enterobactin to limit bacterial iron uptake.
    supporting_text: Binds water, Ca(2+), Na(+), K(+), fatty acids, hormones,
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: >-
      Curated UniProt record (function largely by similarity to human/bovine
      albumin); source for the fatty-acid/metal-ion carrier and enterobactin-binding
      core functions.