Factor IX: Difference between revisions
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'''Step 1:''' Vitamin K is in its active hydroquinone form: In this reaction a proton (H+ ion) is removed from the glutamic acid in an oxygen (O2) consuming reaction. This reaction leads to a carbon ion aring on the glutamic acid molecule. | '''Step 1:''' Vitamin K is in its active hydroquinone form: In this reaction a proton (H+ ion) is removed from the glutamic acid in an oxygen (O2) consuming reaction. This reaction leads to a carbon ion aring on the glutamic acid molecule. | ||
'''Step 2:''' The glutamic acid carbon ion reacts with CO2 forming gamma-carboxyglutamate. | '''Step 2:''' The glutamic acid carbon ion reacts with CO2 forming gamma-carboxyglutamate. | ||
'''Step 3 and 4:''' Active vitamin K in the hydroquinone form is regenerated in two reaction step | '''Step 3 and 4:''' Active vitamin K in the hydroquinone form is regenerated in two reaction step | ||
== γ-Carboxyglutamic Acid (Gla) Domain == | == γ-Carboxyglutamic Acid (Gla) Domain == | ||
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The interaction of the Gla domain with the phospholipid membrane is carried out by binding to phosphatidylserine in the membrane through the interaction of calcium ions. Upon calcium binding to FIX a conformational change occurs in the Gla domain through the clustering of N-terminal hydrophobic residues into a hydrophobic patch, which is then exposed to the solvent. This hydrophobic patch then allows the association of the Gla domain with the cell surface membrane through electrostatic interactions between the phosphoserine head group and arginine and lysine residues in the Gla domain. The basic amino acid residues of factor IX (Lys-5 and Arg-10) bind to the glycerol phosphate backbone and the carboxyl group of the serine interacts with Ca-5 and Ca-6<ref>PMID:500729</ref> allowing membrane association. | The interaction of the Gla domain with the phospholipid membrane is carried out by binding to phosphatidylserine in the membrane through the interaction of calcium ions. Upon calcium binding to FIX a conformational change occurs in the Gla domain through the clustering of N-terminal hydrophobic residues into a hydrophobic patch, which is then exposed to the solvent. This hydrophobic patch then allows the association of the Gla domain with the cell surface membrane through electrostatic interactions between the phosphoserine head group and arginine and lysine residues in the Gla domain. The basic amino acid residues of factor IX (Lys-5 and Arg-10) bind to the glycerol phosphate backbone and the carboxyl group of the serine interacts with Ca-5 and Ca-6<ref>PMID:500729</ref> allowing membrane association. | ||
== Serine Protease Domain == | == Serine Protease Domain == | ||
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Updated on {{REVISIONDAY2}}-{{MONTHNAME|{{REVISIONMONTH}}}}-{{REVISIONYEAR}} | Updated on {{REVISIONDAY2}}-{{MONTHNAME|{{REVISIONMONTH}}}}-{{REVISIONYEAR}} | ||
===Factor IX=== | |||
[[1mgx]], [[1cfi]], [[1cfh]] - hIX GLA domain – human – NMR<br /> | [[1mgx]], [[1cfi]], [[1cfh]] - hIX GLA domain – human – NMR<br /> | ||