Possibly unique subunit(s) of human ferritins responsible for tissue specificity

The biochemical characteristics of human placental and hepatic ferritins were compared. By DEAE cellulose column chromatography, placental ferritin was found to contain more acidic isoferritins, while hepatic ferritin was richer in basic isoferritins. The electrofocusing patterns of subunits revealed that placental ferritin contained at least one unique subunit on the acidic side and might lack one subunit on the basic side as compared with hepatic ferritin. It is hypothesized that microheterogeneities, immunological as well as biochemical, existing between placental and hepatic ferritins cannot be explained merely in terms of different proportions of known acidic and basic subunits, but appear to have resulted from the existence of the unique acidic subunit of placental ferritin and possibly also a unique basic subunit of hepatic ferritin.