Metallothionein--a unique protein with multiple detoxifying properties?

Metallothioneins (MT) are a group of proteins of very peculiar structure, in that 15-20 of its amino acid residues are cysteinyl. We have studied possible functions of the SH-rich MT as a detoxifying molecule by using human and murine cell lines with high amounts of Cd-induced MT. Such cells show radioresistance, they are resistant to Cd, cisplatinum, chlorambucil and gold, and the MT binds these substances firmly. The clinical relevance may be twofold. Firstly, MT may confer resistance to useful drugs such as alkylating agents. Secondly, MT may be a resistance factor to harmful effects of xenobiotics.