Can f 1, the major dog allergen: a secreted lipocalin (calycin superfamily, lipocalin family) homologous to human tear lipocalin / von Ebner's gland protein (LCN1). Produced in tongue (von Ebner) and salivary/skin glands and deposited on hair, it is the dominant dog allergen, recognized by IgE in the majority of dog-allergic patients. Its beta-barrel calyx binds fatty acids (preferring palmitic and oleic acid), as shown by crystallography, fluorescence and NMR studies (PDB structures of Can f 1 with its cross-reactive homolog Fel d 7); the carried lipid may influence allergenicity. The native in-vivo ligand and physiological role of Can f 1 remain to be confirmed.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0005576 extracellular region | IBA GO_REF:0000033 | ACCEPT | Summary: Can f 1 is a secreted lipocalin; extracellular localization is well supported. Reason: Secretory lipocalin acting in the extracellular space. Supporting Evidence: file:CANLF/Canf1/Canf1-uniprot.txt SUBCELLULAR LOCATION: Secreted |
| GO:0005576 extracellular region | IEA GO_REF:0000044 | ACCEPT | Summary: Automated subcellular-location annotation consistent with secretion. Reason: Consistent with the secreted nature of the lipocalin. Supporting Evidence: file:CANLF/Canf1/Canf1-uniprot.txt SUBCELLULAR LOCATION: Secreted |
| GO:0036094 small molecule binding | IEA GO_REF:0000002 | MARK AS OVER ANNOTATED | Summary: Generic small-molecule-binding term. A specific ligand class is now experimentally established for Can f 1 (fatty acids; see the NEW annotation below), so the uninformative parent is superseded. Reason: Uninformative broad parent; the specific fatty-acid binding activity is now demonstrated and annotated. |
| GO:0005504 fatty acid binding | IDA PMID:36960093 Structural and ligand binding analysis of the pet allergens ... | NEW | Summary: NEW (proposed). Crystallographic, fluorescence (ANS-displacement) and NMR analyses show Can f 1 (with its cross-reactive homolog Fel d 7) binds fatty acids in its calyx, preferring palmitic acid (16:0) and oleic acid (18:1). Reason: Direct experimental demonstration of fatty-acid binding (Min et al. 2023); the specific molecular function of this lipocalin's calyx. Supporting Evidence: PMID:36960093 Can f 1 and Fel d 7 bind multiple ligands with |
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Download this section (compressed HTML)Q: What hydrophobic ligand does the major dog allergen Can f 1 transport, and does it share the broad ligand-binding / reported antimicrobial properties of its homolog tear lipocalin (LCN1)?
Experiment: Identify ligands co-purifying with native Can f 1 by LC-MS and test binding of candidate lipids/odorants to recombinant Can f 1 by fluorescent-probe displacement.
Hypothesis: Can f 1 binds a specific small hydrophobic ligand like other von Ebner gland / tear lipocalins.
Type: ligand identification / biophysical binding assay
ALLERGENS backlog (alias Canf1). Secreted lipocalin (calycin/lipocalin family),
homolog of von Ebner gland protein / tear lipocalin (LCN1). MAJOR dog allergen.
IEDB: 83 epitopes, IgE+ (high intervention pressure). No curated UniProt FUNCTION;
GOA only has extracellular region + generic small molecule binding.
Curation: ACCEPT extracellular region (secreted) + small molecule binding (lipocalin,
generic, kept as the only MF clue); core function = lipocalin small-molecule carrier;
knowledge gap: specific ligand/role unknown -> function-gap gene (high priority:
high IEDB load x unknown function).
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