Existing Annotations Review

GO Term	Evidence	Action	Reason
GO:0003779 actin binding	IEA GO_REF:0000002	ACCEPT	Summary: Profilins bind actin; actin binding is a core molecular function of Bet v 2. Reason: Defining function of the profilin family. Supporting Evidence: file:BETPN/Betv2/Betv2-uniprot.txt Binds to actin and affects the structure of the cytoskeleton.
GO:0003785 actin monomer binding	IEA GO_REF:0000118	ACCEPT	Summary: Profilin binds monomeric (G-)actin specifically; the precise core molecular function. Reason: Profilins are G-actin (actin monomer) binding proteins. Supporting Evidence: file:BETPN/Betv2/Betv2-uniprot.txt Binds to actin and affects the structure of the cytoskeleton.
GO:0005856 cytoskeleton	IEA GO_REF:0000044	ACCEPT	Summary: Profilin acts on the actin cytoskeleton; cytoskeletal localization is appropriate. Reason: Consistent with profilin's role in actin cytoskeleton regulation.
GO:0005938 cell cortex	IEA GO_REF:0000118	KEEP AS NON CORE	Summary: Profilin/actin regulation occurs at the cortical cytoskeleton. Reason: Plausible cortical-actin localization; electronic, secondary to the cytoskeletal role.
GO:0005546 phosphatidylinositol-4,5-bisphosphate binding	IEA file:BETPN/Betv2/Betv2-uniprot.txt	NEW	Summary: NEW (proposed). Beyond actin binding, profilins bind phosphatidylinositol 4,5-bisphosphate (PIP2); UniProt records that Bet v 2 binds PIP2 and thereby inhibits IP3/DG formation, linking it to phosphoinositide signalling. Not in GOA. Reason: Curated UniProt function documents PIP2 binding by Bet v 2 (a conserved profilin activity), a specific molecular function absent from the current annotations. Supporting Evidence: file:BETPN/Betv2/Betv2-uniprot.txt By binding to PIP2, it
GO:0070064 proline-rich region binding	IDA PMID:9271223 Birch pollen profilin: structural organization and interacti...	NEW	Summary: NEW (proposed). Poly-L-proline (PLP) binding is a defining biochemical activity of profilins (the basis of the classic poly-L-proline affinity purification). NMR of birch profilin directly maps its PLP-binding site and measures binding to PLP peptides (KD ~0.2 mM for deca-L-proline), including the proline-rich VASP motif. Not currently in GOA. Reason: Direct NMR demonstration of poly-L-proline / proline-rich-motif binding by Bet v 2 (Domke et al. 1997); a defining profilin molecular function absent from the current annotations. Supporting Evidence: PMID:9271223 poly-(L-proline) (PLP)-binding site.

Core Functions

Actin-monomer (G-actin) binding protein (profilin) that regulates actin cytoskeleton dynamics; binds poly-L-proline and PIP2. A conserved plant pan-allergen.

Molecular Function:

actin monomer binding

Cellular Locations:

cytoskeleton

Supporting Evidence:

file:BETPN/Betv2/Betv2-uniprot.txt
Binds to actin and affects the structure of the cytoskeleton.

Binds poly-L-proline / proline-rich motifs (e.g. the VASP motif) through its conserved profilin PLP-binding surface — the defining biochemical activity underlying classic poly-L-proline affinity purification of profilins and profilin's recruitment to proline-rich actin-regulatory ligands.

Molecular Function:

proline-rich region binding

Cellular Locations:

cytoskeleton

Supporting Evidence:

PMID:9271223
poly-(L-proline) (PLP)-binding site.

References

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Suggested Experiments

Experiment: Map Bet v 2 IgE epitopes and compare to actin- and PIP2-binding interfaces; test cross-reactivity against other plant profilins.

Hypothesis: Bet v 2 IgE epitopes overlap conserved actin/PIP2-binding surfaces shared across plant profilins.

Type: epitope mapping / cross-reactivity assay

📚 Additional Documentation

Notes

(Betv2-notes.md)

Betv2 — curation notes (ALLERGENS backlog: mite/birch)

Bet v 2, birch profilin and cross-reactive plant pan-allergen. ACCEPT actin binding/actin monomer binding/cytoskeleton; core actin monomer binding. Characterized.

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