Immunological characterization of metallothioneins in mouse LMTK cells and in a variant resistant to cadmium.

A cadmium-resistant variant isolated from mouse fibroblast LMTK cells can grow in the presence of 40 muM Cd2+. This variant retained its properties in the absence of selecting agent. Induction of metallothionein was measured in cell extracts by radioimmunoassay. The maximum amount of metallothioneins in the cells was reached after 36 hours. The cadmium resistant variant produced two times more metallothionein than the wild-type when exposed to 10-20 muM Cd2+. By Ouchterlony double diffusion, the metallothioneins from cultured cells formed a line of partial identity with the mouse liver serotype and a line of complete identity with one of the two mouse kidney serotypes. These observations raise the possibility of a tissue-specific expression of metallothionein genes.