View source for 1btj


==HUMAN SERUM TRANSFERRIN, RECOMBINANT N-TERMINAL LOBE, APO FORM, CRYSTAL FORM 2==
<StructureSection load='1btj' size='340' side='right'caption='[[1btj]], [[Resolution|resolution]] 3.20&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[1btj]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1BTJ OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1BTJ FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 3.2&#8491;</td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=1btj FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1btj OCA], [https://pdbe.org/1btj PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1btj RCSB], [https://www.ebi.ac.uk/pdbsum/1btj PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1btj ProSAT]</span></td></tr>
</table>
== Disease ==
[https://www.uniprot.org/uniprot/TRFE_HUMAN TRFE_HUMAN] Defects in TF are the cause of atransferrinemia (ATRAF) [MIM:[https://omim.org/entry/209300 209300]. Atransferrinemia is rare autosomal recessive disorder characterized by iron overload and hypochromic anemia.<ref>PMID:11110675</ref> <ref>PMID:15466165</ref> 
== Function ==
[https://www.uniprot.org/uniprot/TRFE_HUMAN 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.
== Evolutionary Conservation ==
[[Image:Consurf_key_small.gif|200px|right]]
Check<jmol>
  <jmolCheckbox>
    <scriptWhenChecked>; select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/bt/1btj_consurf.spt"</scriptWhenChecked>
    <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview03.spt</scriptWhenUnchecked>
    <text>to colour the structure by Evolutionary Conservation</text>
  </jmolCheckbox>
</jmol>, as determined by [http://consurfdb.tau.ac.il/ ConSurfDB]. You may read the [[Conservation%2C_Evolutionary|explanation]] of the method and the full data available from [http://bental.tau.ac.il/new_ConSurfDB/main_output.php?pdb_ID=1btj ConSurf].
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== Publication Abstract from PubMed ==
Serum transferrin binds ferric ions in the bloodstream and transports them to cells, where they are released in a process involving receptor-mediated endocytosis. Iron release is believed to be pH dependent and is coupled with a large conformational change. To help define the steps in iron release, we have determined the three-dimensional structure of the iron-free (apo) form of the recombinant N-lobe half-molecule of human serum transferrin (ApoTfN) by X-ray crystallography. Two crystal forms were obtained, form 1 with four molecules in the asymmetric unit and form 2 with two molecules in the asymmetric unit. The structures of both forms were determined by molecular replacement and were refined at 2.2 and 3.2 A resolution, respectively. Final R-factors were 0.203 (free R = 0. 292) for form 1 and 0.217 (free R = 0.312) for form 2. All six copies of the ApoTfN structure are essentially identical. Comparison with the holo form (FeTfN) shows that a large rigid-body domain movement of 63 degrees has occurred in ApoTfN, to give an open binding cleft. The extent of domain opening is the same as in the N-lobe of human lactoferrin, showing that it depends on internal constraints that are conserved in both proteins, and that it is unaffected by the presence or absence of the C-lobe. Although the conformational change is primarily a rigid-body motion, several local adjustments occur. In particular, two iron ligands, Asp 63 and His 249, change conformation to form salt bridges, with Lys 296 and Glu 83, respectively, in the binding cleft of the apo protein. Both salt bridges would have to break for iron coordination to occur. Most importantly, the structure, determined at a pH (5.3) that is close to the pH of physiological iron release, indicates that protonation of His 249 is a key step in iron release.

Ligand-induced conformational change in transferrins: crystal structure of the open form of the N-terminal half-molecule of human transferrin.,Jeffrey PD, Bewley MC, MacGillivray RT, Mason AB, Woodworth RC, Baker EN Biochemistry. 1998 Oct 6;37(40):13978-86. PMID:9760232<ref>PMID:9760232</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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==See Also==
*[[Transferrin 3D structures|Transferrin 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Homo sapiens]]
[[Category: Large Structures]]
[[Category: Baker EN]]
[[Category: Bewley MC]]
[[Category: Jeffrey PD]]
[[Category: Macgillivray RTA]]
[[Category: Mason AB]]
[[Category: Woodworth RC]]