Desialation of transferrin by liver endothelium: evidence for two cellular pathways for transferrin metabolism.
Transferrin was double-labeled, with its sialic acid residues being labeled with 3H and its protein part with either 125I or 59Fe. Incubation of this double-labeled molecule with fractionated liver endothelium led to the dissociation of the two labels, with 3H being retained and 59Fe and 125I being released from the cell, demonstrating similar patterns. Similar incubation of the double-labeled molecule with K562 cells did not lead to the dissociation of the two labels. The findings provide evidence that liver endothelium desialates Fe-TF complexes and releases the desialated TF still in association with Fe. The findings also provide evidence for a difference in the metabolic pathway of TF in different cell types.
D000818:Animals; D004727:Endothelium / Q000378:metabolism; D066298:In Vitro Techniques; D007700:Kinetics; D008099:Liver / Q000378:metabolism*; D019158:N-Acetylneuraminic Acid; D051381:Rats; D011919:Rats, Inbred Strains; D011990:Receptors, Transferrin / Q000378:metabolism; D012794:Sialic Acids / Q000378:metabolism; D014168:Transferrin / Q000378:metabolism*
D011990:Receptors, Transferrin; D012794:Sialic Acids; D014168:Transferrin; D019158:N-Acetylneuraminic Acid