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Isolated rat hepatocytes accumulate iron from iron‐transferrin by a process which is dependent on the temperature and on the transferrin concentration, and which is diminished by treatment of the cells with a proteolytic enzyme. These observations are consistent with a mechanism for iron uptake into hepatocytes involving the binding of iron‐transferrin to a specific cell‐surface receptor.

Apotransferrin is also able to bind to the hepatocyte but the apparent binding constant is about 35 times lower than that observed for the binding of iron‐transferrin. The binding of apotransferrin to the cells is completely abolished by a low concentration of iron‐transferrin. This suggests that the apotransferrin is binding weakly to the same receptor to which iron‐transferrin binds and that there are no receptors on the surface of the hepatocyte specific for apotransferrin. In the absence of such specific‐binding sites, apotransferrin may …