Structural highlights
Disease
[TRFE_HUMAN] Defects in TF are the cause of atransferrinemia (ATRAF) [MIM:209300]. Atransferrinemia is rare autosomal recessive disorder characterized by iron overload and hypochromic anemia.[1] [2]
Function
[TRFE_HUMAN] Transferrins are iron binding transport proteins which can bind two Fe(3+) ions in association with the binding of an anion, usually bicarbonate. It is responsible for the transport of iron from sites of absorption and heme degradation to those of storage and utilization. Serum transferrin may also have a further role in stimulating cell proliferation.
Publication Abstract from PubMed
Human serum transferrin (hTF) binds Fe(III) tightly but reversibly, and delivers it to cells via a receptor-mediated endocytosis process. The metal-binding and release result in significant conformational changes of the protein. Here, we report the crystal structures of diferric-hTF (Fe(N)Fe(C)-hTF) and bismuth-bound hTF (Bi(N)Fe(C)-hTF) at 2.8 and 2.4 A resolutions respectively. Notably, the N-lobes of both structures exhibit unique "partially-opened" conformations between those of the apo-hTF and holo-hTF. Fe(III) and Bi(III) in the N-lobe coordinate to, besides anions, only two (Tyr95 and Tyr188) and one (Tyr188) tyrosine residues, respectively, in contrast to four residues in the holo-hTF. The C-lobe of both structures are fully closed with iron coordinating to four residues and a carbonate. The structures of hTF observed here represent key conformers captured in the dynamic nature of the transferrin family proteins and provide a structural basis for understanding the mechanism of metal uptake and release in transferrin families.
Iron and bismuth bound human serum transferrin reveals a partially-opened conformation in the N-lobe.,Yang N, Zhang H, Wang M, Hao Q, Sun H Sci Rep. 2012;2:999. doi: 10.1038/srep00999. Epub 2012 Dec 19. PMID:23256035[3]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Beutler E, Gelbart T, Lee P, Trevino R, Fernandez MA, Fairbanks VF. Molecular characterization of a case of atransferrinemia. Blood. 2000 Dec 15;96(13):4071-4. PMID:11110675
- ↑ Knisely AS, Gelbart T, Beutler E. Molecular characterization of a third case of human atransferrinemia. Blood. 2004 Oct 15;104(8):2607. PMID:15466165 doi:10.1182/blood-2004-05-1751
- ↑ Yang N, Zhang H, Wang M, Hao Q, Sun H. Iron and bismuth bound human serum transferrin reveals a partially-opened conformation in the N-lobe. Sci Rep. 2012;2:999. doi: 10.1038/srep00999. Epub 2012 Dec 19. PMID:23256035 doi:10.1038/srep00999
