Sandbox Reserved 596: Difference between revisions

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'''Background'''

~~Protein Z (PZ) is~~ a ~~vitamin k-dependent glycoprotein made~~ in the ~~liver and involved in the blood-clot-forming~~ coagulation cascade. ~~Bovine PZ was first identified by Prowse and Esnouf~~ in ~~1977~~ and ~~Human PZ was first isolated and studied by Broze Jr~~. and ~~Miletich in 1984~~. The ~~gene coding for PZ~~, ~~called PROZ~~, ~~was~~ found ~~in 1998~~ on ~~chromosome 13 at location 13q34~~ and is ~~composed of nine exons~~ (~~one being an alternative exon~~).

The human body maintains the many aspects of homeostasis, or biological equilibrium, through multiple physiological pathways. Hemostatic mechanisms have evolved over 400 million years to protect against the ever-present danger of fatal hemorrhage. [1] When inflicted by a wound resulting in internal or external bleeding, one of the two converging coagulation cascade branches is triggered to maintain hemostasis. If the wound is just an epithelial surface wound, the body reacts with the intrinsic pathway but if the wound is more traumatic, resulting in more extensive vascular and tissue damage, the extrinsic branch is used. This coagulation pathway is known as a cascade because the product of the previous reaction acts as an enzyme for the following reaction, a flow that can be attributed to the specificity of each enzyme along with positive and negative feedback loops to further control the directionality. [2]

The coagulation cascade involves many coagulation factors that act as serine proteases with active sites centered around their serine residues. These serine protease coagulation factors, like factors VII, IX, X, and protein C are vitamin K-dependent proteins, meaning their γ-carboxyglutamic acid residue (Gla) construction within the liver requires fat-soluble vitamin k. Factor Xa (FXa), an essential enzyme found at the intersection of the two coagulation pathways, is formed on platelet membranes through the interaction of factor IXa, complexed with its cofactor VIIIa, on factor X. FXa complexed with its cofactor Va promotes thrombin production from the cleaved zymogen prothrombin. The cascade continues to flow towards its final processes of prothrombin being cleaved into thrombin and thrombin then cleaving fibrinogen to form a meshwork of fibrin until a blood clot stops the bleeding. To ensure that a clot does not form anywhere other than the injury site, any FXa that dissociates from the membrane must be inhibited. FXa is regulated by two serine protease inhibitors (serpins), antithrombin and protein z-dependent inhibitor (ZPI) that are inactive to FXa until paired with their cofactors heparin and protein z (PZ) respectively. [3]

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Sandbox Reserved 596: Difference between revisions

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@@ Line 27: / Line 27: @@
 '''Background'''
-Protein Z (PZ) is a vitamin k-dependent glycoprotein made in the liver and involved in the blood-clot-forming coagulation cascade. Bovine PZ was first identified by Prowse and Esnouf in 1977 and Human PZ was first isolated and studied by Broze Jr. and Miletich in 1984. The gene coding for PZ, called PROZ, was found in 1998 on chromosome 13 at location 13q34 and is composed of nine exons (one being an alternative exon).
+The human body maintains the many aspects of homeostasis, or biological equilibrium, through multiple physiological pathways. Hemostatic mechanisms have evolved over 400 million years to protect against the ever-present danger of fatal hemorrhage. [1] When inflicted by a wound resulting in internal or external bleeding, one of the two converging coagulation cascade branches is triggered to maintain hemostasis.  If the wound is just an epithelial surface wound, the body reacts with the intrinsic pathway but if the wound is more traumatic, resulting in more extensive vascular and tissue damage, the extrinsic branch is used. This coagulation pathway is known as a cascade because the product of the previous reaction acts as an enzyme for the following reaction, a flow that can be attributed to the specificity of each enzyme along with positive and negative feedback loops to further control the directionality. [2]
+The coagulation cascade involves many coagulation factors that act as serine proteases with active sites centered around their serine residues. These serine protease coagulation factors, like factors VII, IX, X, and protein C are vitamin K-dependent proteins, meaning their γ-carboxyglutamic acid residue (Gla) construction within the liver requires fat-soluble vitamin k. Factor Xa (FXa), an essential enzyme found at the intersection of the two coagulation pathways, is formed on platelet membranes through the interaction of factor IXa, complexed with its cofactor VIIIa, on factor X. FXa complexed with its cofactor Va promotes thrombin production from the cleaved zymogen prothrombin. The cascade continues to flow towards its final processes of prothrombin being cleaved into thrombin and thrombin then cleaving fibrinogen to form a meshwork of fibrin until a blood clot stops the bleeding. To ensure that a clot does not form anywhere other than the injury site, any FXa that dissociates from the membrane must be inhibited. FXa is regulated by two serine protease inhibitors (serpins), antithrombin and protein z-dependent inhibitor (ZPI)  that are inactive to FXa until paired with their cofactors heparin and protein z (PZ) respectively. [3]
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