The function of metallothionein in cell metabolism

Rat hepatocytes were obtained and cultured in media containing 65Zn in the presence or absence of insulin and hepatocyte growth factors. Cells were also grown in a pulse-chase type of experiment. After varying periods of incubation the cells were harvested and assayed for zinc, protein and metallothionein. Although the amount of intracellular zinc (Zn/cell protein) was constant, the amount of metallothionein (MT/cell protein) in the cells exposed to zinc alone increased to a level approximately five times higher than the cells cultured in the presence of the growth factors. Chromatographs established that for cell cultured in the absence of hepatocyte growth factors all the 65Zn coeluted with metallothionein whereas for cultures maintained in the presence of these factors the zinc was associated with higher molecular weight components in addition to being present in the 10,000 dalton peak.