Biological role of metallothioneins is to sequester harmful metal ions. These bind which of the following ions?
Metallothioneins are metal binding proteins of relatively low molecular mass with a high content of cysteine residues that have a paicular affinity for cadmium, as well as for zinc and copper. Zinc metallothioneins can detoxify free radicals. Cadmium induced metallothioneins is able to bind cadmium intracellularly and in this way protects the organism against the toxicity of this metal. Ref: Mineral Components in Foods edited by Piotr Szefer page 152
Cd++, Cu++ & Zn++
Al+++, Hg++ & NH4+
Pt++, As+++ & P04
Fe+++, Na+ & K+