AF209: Metallothionein

List allergens from this family:

Routes of exposure:
Include only IUIS approved allergens.

Biochemical properties

Metallothioneins are a family of cysteine-rich, low molecular weight proteins. They bind both physiological (such as zinc, copper, selenium) and xenobiotic (such as cadmium, mercury, silver, arsenic) heavy metals through the thiol group of their cysteine residues, which represent nearly 30% of their amino acid residues. Metallothioneins are ubiquitously distributed and have highly diverse sequences. Sequence homology appears to be confined to proteins within taxonomic groups.

Allergens from this family

Dust of green coffee beans is a relevant cause for occupational allergy in coffee industry workers. The coffee dust allergens Cof a 2 and Cof a 3 are metallothioneins [1].



  1. Peters U, Frenzel K, Brettschneider R, Oldenburg M, Bittner C:
    Identification of two metallothioneins as novel inhalative coffee allergens cof a 2 and cof a 3.
    PLoS One 2015, 10, e0126455. [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
PF01439 Metallothionein -

Links to Wikipedia


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