1fqf

CRYSTAL STRUCTURES OF MUTANT (K296A) THAT ABOLISH THE DILYSINE INTERACTION IN THE N-LOBE OF HUMAN TRANSFERRIN

spinqualitylabelsall models 1fqf, resolution 2.10Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1fqf is a 1 chain structure with sequence from Homo sapiens. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.1Å Ligands: CO3, FE Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT 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. 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. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed Human transferrin (Tf) is responsible for the binding and transport of iron in the bloodstream of vertebrates. Delivery of this bound iron to cells occurs by a process of receptor-mediated endocytosis during which Tf releases its iron at the reduced endosomal pH of approximately 5.6. Iron release from Tf involves a large conformational change in which the two domains that enclose the binding site in each lobe move apart. We have examined the role of two lysines, Lys206 and Lys296, that form a hydrogen-bonded pair close to the N-lobe binding site of human Tf and have been proposed to form a pH-sensitive trigger for iron release. We report high-resolution crystal structures for the K206A and K296A mutants of the N-lobe half-molecule of Tf, hTf/2N, and quantitative iron release data on these mutants and the double mutant K206A/K296A. The refined crystal structures (for K206A, R = 19.6% and R(free) = 23.7%; for K296A, R= 21.2% and R(free) = 29.5%) reveal a highly conserved hydrogen bonding network in the dilysine pair region that appears to be maintained even when individual hydrogen bonding groups change. The iron release data show that the mutants retain iron to a pH 1 unit lower than the pH limit of wild type hTf/2N, and release iron much more slowly as a result of the loss of the dilysine interaction. Added chloride ions are shown to accelerate iron release close to the pH at which iron is naturally lost and the closed structure becomes destabilized, and to retard it at higher pH. Crystal structures and iron release properties of mutants (K206A and K296A) that abolish the dilysine interaction in the N-lobe of human transferrin.,Nurizzo D, Baker HM, He QY, MacGillivray RT, Mason AB, Woodworth RC, Baker EN Biochemistry. 2001 Feb 13;40(6):1616-23. PMID:11327820 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Transferrin 3D structures

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