response to vitamin K

Definition

Target type: biologicalprocess

Any process that results in a change in state or activity of a cell or an organism (in terms of movement, secretion, enzyme production, gene expression, etc.) as a result of a vitamin K stimulus. [GOC:sl]

Vitamin K is a fat-soluble vitamin that plays a crucial role in blood clotting and bone health. It acts as a cofactor for enzymes involved in the gamma-carboxylation of specific glutamate residues in proteins. This process is essential for the activation of several clotting factors, including prothrombin, factor VII, factor IX, and factor X. These clotting factors, once activated, participate in the coagulation cascade, a series of enzymatic reactions that lead to the formation of a fibrin clot, which helps to stop bleeding.

The response to vitamin K begins with the absorption of vitamin K from dietary sources, primarily green leafy vegetables. After absorption, vitamin K is transported to the liver, where it undergoes a series of enzymatic reactions. These reactions involve the reduction of vitamin K epoxide to vitamin K hydroquinone, which is the active form of the vitamin.

Vitamin K hydroquinone then acts as a cofactor for the enzyme gamma-glutamyl carboxylase (GGCX). GGCX catalyzes the carboxylation of glutamate residues in specific proteins, including the clotting factors mentioned above. This carboxylation reaction is essential for the activation of these proteins, as it allows them to bind calcium ions and participate in the coagulation cascade.

The carboxylation reaction involves the transfer of a carbon dioxide molecule from bicarbonate to the glutamate residue in the protein. This reaction is dependent on vitamin K hydroquinone, which acts as an electron carrier. During this reaction, vitamin K hydroquinone is oxidized to vitamin K epoxide. Vitamin K epoxide is then reduced back to vitamin K hydroquinone by an enzyme called vitamin K reductase. This cycle of reduction and oxidation allows for the continuous activation of GGCX and the carboxylation of glutamate residues in proteins.

Deficiency in vitamin K can lead to a decrease in the synthesis of active clotting factors, resulting in an increased risk of bleeding. This condition is known as vitamin K deficiency bleeding. Other factors that can contribute to vitamin K deficiency include malabsorption, certain medications, and liver disease.

In addition to its role in blood clotting, vitamin K also plays an important role in bone health. It is required for the activation of osteocalcin, a protein that helps to regulate bone mineralization. Vitamin K deficiency can therefore lead to reduced bone density and an increased risk of osteoporosis.'
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Proteins (2)

Compounds (30)