Transferrin receptors and the uptake and release of iron by isolated hepatocytes.
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 not receptors on the surface of the hepatocyte specific for apotransferrin. In the absence of such specific-binding sites, apotransferrin may act as a passive acceptor of iron released from the hepatocyte.
D000818:Animals; D001059:Apoproteins; D003676:Deferoxamine / Q000494:pharmacology; D066298:In Vitro Techniques; D007501:Iron / Q000378:metabolism*; D008099:Liver / Q000378:metabolism*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D011956:Receptors, Cell Surface / Q000378:metabolism*; D011990:Receptors, Transferrin; D014168:Transferrin / Q000378:metabolism
D001059:Apoproteins; D011956:Receptors, Cell Surface; D011990:Receptors, Transferrin; D014168:Transferrin; C028284:apotransferrin; C028283:diferric transferrin; D007501:Iron; D003676:Deferoxamine