4zma

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== Function ==
== Function ==
[[http://www.uniprot.org/uniprot/FA7_HUMAN FA7_HUMAN]] Initiates the extrinsic pathway of blood coagulation. Serine protease that circulates in the blood in a zymogen form. Factor VII is converted to factor VIIa by factor Xa, factor XIIa, factor IXa, or thrombin by minor proteolysis. In the presence of tissue factor and calcium ions, factor VIIa then converts factor X to factor Xa by limited proteolysis. Factor VIIa will also convert factor IX to factor IXa in the presence of tissue factor and calcium. [[http://www.uniprot.org/uniprot/TF_HUMAN TF_HUMAN]] Initiates blood coagulation by forming a complex with circulating factor VII or VIIa. The [TF:VIIa] complex activates factors IX or X by specific limited protolysis. TF plays a role in normal hemostasis by initiating the cell-surface assembly and propagation of the coagulation protease cascade.<ref>PMID:12652293</ref>
[[http://www.uniprot.org/uniprot/FA7_HUMAN FA7_HUMAN]] Initiates the extrinsic pathway of blood coagulation. Serine protease that circulates in the blood in a zymogen form. Factor VII is converted to factor VIIa by factor Xa, factor XIIa, factor IXa, or thrombin by minor proteolysis. In the presence of tissue factor and calcium ions, factor VIIa then converts factor X to factor Xa by limited proteolysis. Factor VIIa will also convert factor IX to factor IXa in the presence of tissue factor and calcium. [[http://www.uniprot.org/uniprot/TF_HUMAN TF_HUMAN]] Initiates blood coagulation by forming a complex with circulating factor VII or VIIa. The [TF:VIIa] complex activates factors IX or X by specific limited protolysis. TF plays a role in normal hemostasis by initiating the cell-surface assembly and propagation of the coagulation protease cascade.<ref>PMID:12652293</ref>
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== Publication Abstract from PubMed ==
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The complex of coagulation factor VIIa (FVIIa), a trypsin-like serine protease, and membrane bound tissue factor (TF) initiates blood coagulation upon vascular injury. Binding of TF to FVIIa promotes allosteric conformational changes in the FVIIa protease domain and improves its catalytic properties. Extensive studies have revealed two putative pathways for this allosteric communication. Here we provide further details of this allosteric communication by investigating FVIIa loop swap variants containing the 170-loop of trypsin that display TF-independent enhanced activity. Using x-ray crystallography, we show that the introduced 170-loop from trypsin directly interacts with the FVIIa active-site, stabilizing segment 215-217a and activation loop 3, leading to enhanced activity. Molecular dynamics simulations and novel fluorescence quenching studies support that segment 215-217 conformation is pivotal to the enhanced activity of the FVIIa variants. We speculate that the allosteric regulation of FVIIa activity by TF binding follows a similar path in conjunction with N-terminus insertion, suggesting a more complete molecular basis of TF-mediated allosteric enhancement of FVIIa activity.
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Molecular Basis of Enhanced Activity in Factor VIIa-Trypsin Variants Conveys Insights into Tissue Factor-Mediated Allosteric Regulation of Factor VIIa Activity.,Sorensen AB, Madsen JJ, Svensson LA, Pedersen AA, Ostergaard H, Overgaard MT, Olsen OH, Gandhi PS J Biol Chem. 2015 Dec 22. pii: jbc.M115.698613. PMID:26694616<ref>PMID:26694616</ref>
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From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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== References ==
== References ==
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<references/>

Revision as of 12:16, 13 January 2016

Crystal Structure of a FVIIa-Trypsin Chimera (ST) in Complex with Soluble Tissue Factor

4zma, resolution 2.30Å

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