Interactions between metallothionein and trace elements.

Metallothionein is an important metal-binding protein which occurs in varying amounts in a wide range of tissues but particularly in liver, kidneys, intestine and pancreas. Synthesis of the protein is induced by zinc and copper and also by cadmium and many other non-essential elements. The concentration of the protein in tissues depend on zinc and copper status and on patho-physiological state. A variety of stress factors stimulate metallothionein synthesis, particularly in liver. The turnover rate of metallothionein in tissues is relatively high but depends to a large extent on its metal content. There has been much speculation as to the function of the protein and one important role appears to lie in the cellular detoxification of copper, zinc and other metals. Metallothionein also appears to participate in metabolic interactions between zinc and copper. The protein occurs in small amounts in blood and urine and assay of these concentrations may be used in the assessment of trace element status.