Proteins encoded by the metallothionein gene family are low in molecular weight, are cysteine-rich, lack aromatic residues, and bind divalent heavy metal ions. The conserved cysteine residues co-ordinate metal ions using mercaptide linkages. These proteins act as anti-oxidants, protect against hydroxyl free radicals, are important in the homeostatic control of metal in the cell, and play a role in the detoxification of heavy metals.
Monoclonal antibodies were raised against purified human metallothionein-1 (hMT-1) and have been used in an ELISA for this protein.