Recent developments in trace element metabolism and function: role of metallothionein in copper and zinc metabolism.

Metallothionein is a copper- and zinc-binding protein present in most, if not all, tissues of higher eukaryotic species of animals. This review focuses on what is currently known about the characteristics, detection, occurrence, synthesis and turnover of metallothionein, specifically in livestock animals. The function of metallothionein in copper and zinc metabolism, though widely acknowledged, remains controversial. Current evidence in support of a role in the detoxification as well as in the homeostasis of copper and zinc is presented, along with a proposed model summarizing the involvement of metallothionein in basic cellular metabolism of copper and zinc. Also discussed are potential implications of metallothionein in animal agriculture.