View source for 1tfa

[[Image:1tfa.gif|left|200px]]<br /><applet load="1tfa" size="350" color="white" frame="true" align="right" spinBox="true" 
caption="1tfa, resolution 1.90&Aring;" />
'''OVOTRANSFERRIN, N-TERMINAL LOBE, APO FORM'''<br />

==Overview==
Transferrins bind Fe3+ very tightly in a closed interdomain cleft by the coordination of four protein ligands (Asp60, Tyr92, Tyr191, and His250 in ovotransferrin N-lobe) and of a synergistic anion, physiologically bidentate CO32-. Upon Fe3+ uptake, transferrins undergo a large scale conformational transition: the apo structure with an opening of the interdomain cleft is transformed into the closed holo structure, implying initial Fe3+ binding in the open form. To solve the Fe3+-loaded, domain-opened structure, an ovotransferrin N-lobe crystal that had been grown as the apo form was soaked with Fe3+-nitrilotriacetate, and its structure was solved at 2.1 A resolution. The Fe3+-soaked form showed almost exactly the same overall open structure as the iron-free apo form. The electron density map unequivocally proved the presence of an iron atom with the coordination by the two protein ligands of Tyr92-OH and Tyr191-OH. Other Fe3+ coordination sites are occupied by a nitrilotriacetate anion, which is stabilized through the hydrogen bonds with the peptide NH groups of Ser122, Ala123, and Gly124 and a side chain group of Thr117. There is, however, no clear interaction between the nitrilotriacetate anion and the synergistic anion binding site, Arg121.

==About this Structure==
1TFA is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Gallus_gallus Gallus gallus] with <scene name='pdbligand=SO4:'>SO4</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1TFA OCA]. 

==Reference==
Alternative structural state of transferrin. The crystallographic analysis of iron-loaded but domain-opened ovotransferrin N-lobe., Mizutani K, Yamashita H, Kurokawa H, Mikami B, Hirose M, J Biol Chem. 1999 Apr 9;274(15):10190-4. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=10187803 10187803]
[[Category: Gallus gallus]]
[[Category: Single protein]]
[[Category: Hirose, M.]]
[[Category: Mikami, B.]]
[[Category: Mizutani, K.]]
[[Category: Yamashita, H.]]
[[Category: SO4]]
[[Category: iron binding protein]]
[[Category: ovotransferrin]]
[[Category: transferrin]]

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