HEPATIC SUBCELLULAR METABOLISM OF HEME FROM HEME-HEMOPEXIN - INCORPORATION OF IRON INTO FERRITIN

The subcellular distribution and metabolic fate of [59Fe]heme-[125I]-labeled hemopexin after receptor-mediated interaction with the liver was examined in the rat. After intravenous injection, [59Fe]heme from the complex and 59Fe from hepatic catabolism of this heme accumulate in the liver and undergo changes in their subcellular distribution over 2 hours. The amounts of [59Fe]heme and particularly of 59Fe increase in the cytosol while remaining constant or decreasing in membranous fractions. In contrast, [125I]-labeled hemopexin associated with the liver during heme transport is always a small fraction of the dose and is not measurably catabolized under these conditions. Gel filtration of the cytosol showed that 59Fe increased linearly with time in a high molecular weight fraction which was identified immunologically as ferritin. We conclude that heme transported by hemopexin is metabolized by the liver and the iron conserved. © 1979.