Metallothionein 3, also known as MT3, binds heavy metals. This protein contains three zinc and three copper atoms per polypeptide chain and only a negligible amount of cadmium. This protein inhibits survival and neurite formation of cortical neurons in vitro. Recombinant human MT3 protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.