AF206: Thionin

List allergens from this family:

Routes of exposure:
Include only IUIS approved allergens.

Biochemical properties

Thionins are small proteins found solely in higher plants. Typically, a thionin consists of 45-48 amino acid residues. 6-8 of these are cysteines forming 3-4 disulfide bonds. α- and β-thionins are related to each other. The γ-thionins have a superficially similar structure but are an unrelated class of protein, now called plant defensins (AllFam:AF059). Thionins are toxic to animal cells, presumably attacking the cell membrane and rendering it permeable. They are mainly found in seeds where they may act as a defence against consumption by animals [1].

Allergens from this family

Alpha-purothionin from wheat was identified as a minor food allergen [2].



  1. Florack DE, Stiekema WJ:
    Thionins: properties, possible biological roles and mechanisms of action.
    Plant Mol Biol 1994, 26, 25-37. [PubMed]
  2. Pahr S, Constantin C, Papadopoulos NG, Giavi S, Makela M, Pelkonen A, Ebner C, Mari A, Scheiblhofer S, Thalhamer J, Kundi M, Vrtala S, Mittermann I, Valenta R:
    alpha-Purothionin, a new wheat allergen associated with severe allergy.
    J Allergy Clin Immunol 2013, 132, 1000-3 e1-4. [PubMed] [Full Text]


Links to Pfam

Family-defining Pfam domains (at least one of these domains is present in each family member):

Pfam domain Pfam clan
PF00321 Plant thionin -

Links to Wikipedia


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