Selection of Saccharomyces cerevisiae BD101 having resistance to metal ions and producing metallothionein by inducer from Saccharomyces. These proteins were isolated and purified by Sephadex G-50 and subsequent DEAE Sepharose CL-4B, then Sephadex G-25 for desalination. There were two iso-MTs for Cu-induced. The, molecular weights were 7 kD and had 60 amino acids. Both Cu-MTs were rich in Cysteine (10%). 4 atom Cu/6 mole Cys/mole Cu-MTs.