Molecular structures involved in 67Ga and 59Fe binding by placenta and tumors.

The binding of 67Ga and 59Fe by placenta and tumors was compared. After sonification, about 50% of the total radioactivity was present in the insoluble fraction consisting of heavy subcellular particles (mitochondria, fragments of membranes, nuclei, etc.) and known to be rich in lipo- and glycoproteins. Heat denaturation and gel filtration were used to study transferrin and ferritin distribution in the supernatant. The differences between 59Fe and 67Ga uptake in this supernatant seemed to indicate that the transferrin-ferritin system plays a less important role in 67Ga binding than in 59Fe binding.