Correlations between iron content and isoferritin profiles of normal and malignant tissues

Isoelectric focusing profiles of ferritins isolated from livers of anemic rats and 3'-methyl-4-dimethylaminoazobenzene-induced hepatomas were more acidic than their normal counterparts, and exhibited patterns similar to those of heart ferritin. Iron administration induced a shift to more basic components for the normal and tumor ferritins. The isoferritin patterns reflected the subunit populations of the protein, as the more acidic components had greater proportions of H-type subunits and iron induced an increase in L subunits with concomitant increases in more basic isoferritins. For both normal and malignant tissues there was a direct correlation between iron content of the tissue and subunit composition. The apparently unique isoferritin patterns in the tumor tissue may, therefore, be ascribed primarily to the lower iron contents.