Competitive advantage of diferric transferrin in delivering iron to reticulocytes.
Radioiron- and radioiodine-labeled forms of human diferric and monoferric transferrin and apotransferrin, isolated by preparative isoelectric focusing, were used to define transferrin-iron uptake by human reticulocytes. In mixtures of human diferric and monoferric transferrin, the diferric molecule had a constant 7-fold advantage in delivering iron to reticulocytes, as compared with the 2-fold advantage when single solutions of mono- and diferric transferrins were compared. This was shown to be due to competitive interaction in iron delivery, probably at a common membrane-receptor binding site for transferrin. Apotransferrin did not interfere with the iron-donating process and its limited cellular uptake was inhibited in noncompetitive fashion by diferric transferrin.
D001059:Apoproteins / Q000378:metabolism; D001692:Biological Transport; D006801:Humans; D007501:Iron / Q000378:metabolism; D012156:Reticulocytes / Q000378:metabolism*; D013329:Structure-Activity Relationship; D014168:Transferrin / Q000378:metabolism*
D001059:Apoproteins; D014168:Transferrin; D007501:Iron