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The precise function of vitamin K was not discovered until 1974, when prothrombin, a blood coagulation protein, was confirmed to be vitamin K dependent. When the vitamin is present, prothrombin has amino acids near the amino terminus of the protein as γ-carboxyglutamate instead of glutamate, and is able to bind calcium, part of the clotting ...
Vitamin K is an essential factor to the hepatic gamma-glutamyl carboxylase that adds a carboxyl group to glutamic acid residues on factors II, VII, IX and X, as well as Protein S, Protein C and Protein Z. In adding the gamma-carboxyl group to glutamate residues on the immature clotting factors, Vitamin K is itself oxidized.
The coagulation pathway helps the body stop active bleeds by using vitamin K dependent clotting factors (factors II, VII, IX, and X) which are synthesized by the liver. [2] [3] [6] Vitamin K can be delivered into the body via the oral, subcutaneous, intramuscular, or intravenous routes of administration. [7]
Vitamin K is changed to its active form in the liver by the enzyme Vitamin K epoxide reductase. Activated vitamin K is then used to gamma carboxylate (and thus activate) certain enzymes involved in coagulation: Factors II, VII, IX, X, and protein C and protein S. Inability to activate the clotting cascade via these factors leads to the bleeding ...
Gamma-glutamyl carboxylase is an enzyme that catalyzes the posttranslational modification of vitamin K -dependent proteins. Many of these vitamin K-dependent proteins are involved in coagulation so the function of the encoded enzyme is essential for hemostasis. [5] Most gla domain -containing proteins depend on this carboxylation reaction for ...
Protein S (also known as PROS) is a vitamin K -dependent plasma glycoprotein synthesized in the liver. In the circulation, Protein S exists in two forms: a free form and a complex form bound to complement protein C4b-binding protein (C4BP). In humans, protein S is encoded by the PROS1 gene. [5][6] Protein S plays a role in coagulation.
A vitamin K-dependent clotting factor is seldom seen as a contributor to inherited prothrombin deficiencies, but lack of Vitamin K decreases the synthesis of prothrombin in liver cells. [5] Acquired underlying causes of this condition include severe liver disease, warfarin overdose, platelet disorders, and disseminated intravascular coagulation ...
The availability of reduced vitamin K is of importance for activation vitamin K 2,3-epoxide. The reduction of vitamin K epoxide is then responsible for the carboxylation of glutamic acid residues in some blood-clotting proteins, including factor VII, factor IX, and factor X. [5] [7] VKORC1 is of therapeutic interest both for its role in ...