1j35

Crystal Structure of Ca(II)-bound Gla Domain of Factor IX Complexed with Binding Protein

spinqualitylabelsall models 1j35, resolution 1.80Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1j35 is a 3 chain structure with sequence from Bos taurus and Trimeresurus flavoviridis. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: CA NonStd Res: CGU Related: 1iod, 1bj3, 1j34 Activity: Coagulation factor IXa, with EC number 3.4.21.22 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [FA9_BOVIN] Factor IX is a vitamin K-dependent plasma protein that participates in the intrinsic pathway of blood coagulation by converting factor X to its active form in the presence of Ca(2+) ions, phospholipids, and factor VIIIa. [IXXB_PROFL] When linked to subunit A of IX/X-bp, anticoagulant protein which binds to the gamma-carboxyglutamic acid-domain regions of factors IX (F9) and factor X (10) in the presence of calcium with a 1 to 1 stoichiometry. When linked to subunit A of IX-bp, anticoagulant protein which binds to the gamma-carboxyglutamic acid-domain regions of factor IX (but not to factor X) in the presence of calcium with a 1 to 1 stoichiometry. 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 Factor IX is an indispensable protein required in the blood coagulation cascade. It binds to the surface of phospholipid membrane by means of a gamma-carboxyglutamic acid (Gla) domain situated at the N terminus. Recently, we showed that physiological concentrations of Mg2+ ions affect the native conformation of the Gla domain and in doing so augment the biological activity of factor IXa and binding affinity with its binding protein even in the presence of Ca2+ ions. Here we report on the crystal structures of the Mg2+/Ca2+-bound and Ca2+-bound (Mg2+-free) factor IX Gla domain (IXGD1-46) in complex with its binding protein (IX-bp) at 1.55 and 1.80 A resolutions, respectively. Three Mg2+ and five Ca2+ ions were bound in the Mg2+/Ca2+-bound IXGD1-46, and the Mg2+ ions were replaced by Ca2+ ions in Mg2+-free IXGD1-46. Comparison of Mg2+/Ca2+-bound with Ca2+-bound structures of the complexes showed that Mg2+ ion, which formed a bridge between IXGD1-46 and IX-bp, forced IXGD1-46 to rotate 4 degrees relative to IX-bp and hence might be the cause of a more tight interaction between the molecules than in the case of the Mg2+-free structure. The results clearly suggest that Mg2+ ions are required to maintain native conformation and in vivo function of factor IX Gla domain during blood coagulation. Crystal structure of Mg2+- and Ca2+-bound Gla domain of factor IX complexed with binding protein.,Shikamoto Y, Morita T, Fujimoto Z, Mizuno H J Biol Chem. 2003 Jun 27;278(26):24090-4. Epub 2003 Apr 14. PMID:12695512 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Factor IX 3D structures

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