Factor IX: Difference between revisions
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{{STRUCTURE_1pfx| PDB=1pfx | SIZE= | {{STRUCTURE_1pfx| PDB=1pfx | SIZE=400| SCENE= |right| CAPTION=pig factor IX complex with tripeptide, [[1pfx]] }} | ||
<span style="color:Brown">'''<scene name='Factor_IX/Ixstructure/4'>Factor IX</scene>'''</span> (plasma thromboplastin component, Christmas factor, or hemophilia B factor) is a 57-kDa vitamin K-dependent procoagulant glycoprotein. It is synthesized by the liver hepatocyte as a [[pre-prozymogen]] that requires extensive posttranslational modification<ref>PMID:2169923</ref>. The [[pre-prozymogen]] contains a pre-peptide (hydrophobic signal peptide) at its amino terminal that transports the growing polypeptide into the lumen of the Endoplasmic Reticulum. Once inside the ER, this signal peptide is cleaved by a signal peptidase. | <span style="color:Brown">'''<scene name='Factor_IX/Ixstructure/4'>Factor IX</scene>'''</span> (plasma thromboplastin component, Christmas factor, or hemophilia B factor) is a 57-kDa vitamin K-dependent procoagulant glycoprotein. It is synthesized by the liver hepatocyte as a [[pre-prozymogen]] that requires extensive posttranslational modification<ref>PMID:2169923</ref>. The [[pre-prozymogen]] contains a pre-peptide (hydrophobic signal peptide) at its amino terminal that transports the growing polypeptide into the lumen of the Endoplasmic Reticulum. Once inside the ER, this signal peptide is cleaved by a signal peptidase. | ||
A [[pro-peptide]] functions as a recognition element for a vitamin K-dependent carboxylase (γ-glutamyl carboxylase) which modifies 12 glutamic acid residues to gamma-carboxyglutamyl (<scene name='Factor_IX/Ixstructure_residue/3'>Gla</scene>) residues<ref>PMID:12554099</ref>. These residues are required for the association with the anionic phospholipid surface through Ca2+-dependent binding. | A [[pro-peptide]] functions as a recognition element for a vitamin K-dependent carboxylase (γ-glutamyl carboxylase) which modifies 12 glutamic acid residues to gamma-carboxyglutamyl (<scene name='Factor_IX/Ixstructure_residue/3'>Gla</scene>) residues<ref>PMID:12554099</ref>. These residues are required for the association with the anionic phospholipid surface through Ca2+-dependent binding. Additional details in [[Calcium ions the Gla domain]]. | ||
The Gla Domain is followed by two epidermal growth factor domains (<scene name='Factor_IX/Ixstructure_egf1/3'>EGF-1</scene> and <scene name='Factor_IX/Ixstructure_egf2/3'>EGF-2</scene>). The N-terminus of EGF-1 contains a Ca2+ binding site, while the C-terminus connects to a hydrophobic pocket of EGF-2 by a salt bridge through Lys122 (EGF-1 residue) and Gln74 (EGF-2)<ref>PMID:11723140</ref>. EGF-2 connects to the <scene name='Factor_IX/Ixstructure_chainc/3'>serine protease</scene> domain through a linker peptide that is required for a proper orientation and folding of serine proteases. To have a physiologically active factor IX, two cleavages must occur to remove a 35 amino acid region that precedes the catalytic site. | The Gla Domain is followed by two epidermal growth factor domains (<scene name='Factor_IX/Ixstructure_egf1/3'>EGF-1</scene> and <scene name='Factor_IX/Ixstructure_egf2/3'>EGF-2</scene>). The N-terminus of EGF-1 contains a Ca2+ binding site, while the C-terminus connects to a hydrophobic pocket of EGF-2 by a salt bridge through Lys122 (EGF-1 residue) and Gln74 (EGF-2)<ref>PMID:11723140</ref>. EGF-2 connects to the <scene name='Factor_IX/Ixstructure_chainc/3'>serine protease</scene> domain through a linker peptide that is required for a proper orientation and folding of serine proteases. To have a physiologically active factor IX, two cleavages must occur to remove a 35 amino acid region that precedes the catalytic site. | ||
