Effect of iron on the biosynthesis of hepatic apoferritin.

Apoferritin is the protein which may play a part in the transport system for iron in the gastrointestinal cells and which serves as the main reservoir of storage iron in the liver and spleen. In combination with iron it is called ferritin. The oral administration of iron to an animal has been shown to stimulate the formation of apoferritin in the mucosa of the gastrointestinal tract. Granick (1) reported that there is a marked increase in the amount of crystallizable apoferritin chiefly in the mucosa of the upper intestinal tract of guinea pigs fed iron. Gabrio and Salomon (2) demonstrated that considerably more ferritin could be isolated from the intestinal mucosa and adjacent lymph nodes of a horse fed iron in comparison with an untreated control. Since the precipitin method of isolation employed by the latter investigators does not distinguish between apoferritin and ferritin, it is assumed that the total amount of iron storage protein was increased following the priming of animals with iron. The present study indicates that while the in vivo incorporation of glycine labelled with C14 into ferritin (apoferritin plus ferritin) is increased by oral administration of iron, intraperitoneal injection of iron is considerably more effective in promoting this incorporation, presumably because the iron has direct access to the hepatic cells concerned with synthesis of this protein. Ferritin isolated from the mucosa of the gastrointestinal tract and from the liver of resting animals appears to be in the dynamic state. Attempts at in uitro incorporation of labelled glycine into liver ferritin have been successful, and an opportunity is afforded for the study of factors influencing biosynthesis of ferritin. While these investigations were in progress