Albumin prevents nonspecific transferrin binding and iron uptake by isolated hepatocytes.
Bovine serum albumin inhibits binding of transferrin by hepatocytes in suspension by 60-70%. Iron uptake is inhibited by less than 20%. A Scatchard analysis of the transferrin-binding data reveals a biphasic plot in the absence of bovine serum albumin, but a monophasic plot in the presence of bovine serum albumin. Bovine serum albumin inhibits low-affinity binding of transferrin (125000 molecules/cell), but has no effect on high-affinity binding (38000 molecules/cell). In pronase-treated cells, transferrin binding is reduced by 40%, and when bovine serum albumin is added, the binding is reduced by a further 40%. Corresponding figures for iron uptake are 70 and 10%, respectively. The results are strong evidence that the major part of iron uptake by hepatocytes occurs from transferrin bound to the plasma membrane transferrin receptor.
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D005260:Female; D007501:Iron / Q000378:metabolism*; D007700:Kinetics; D008099:Liver / Q000378:metabolism*; D051381:Rats; D011956:Receptors, Cell Surface / Q000378:metabolism; D011990:Receptors, Transferrin; D012710:Serum Albumin, Bovine / Q000494:pharmacology*; D014168:Transferrin / Q000378:metabolism*
D011956:Receptors, Cell Surface; D011990:Receptors, Transferrin; D014168:Transferrin; D012710:Serum Albumin, Bovine; D007501:Iron