Tissue factor

(Redirected from Platelet factor 3)

Definition

noun

An integral membrane glycoprotein (made up of about 250 residues) that initiates blood clotting after binding factors VII (or VIIa)


Supplement

Coagulation, the process of clot formation, involves platelet and blood clotting factors. In humans, the coagulation mechanism is comprised of two processes, i.e. the primary hemostasis and the secondary hemostasis. The latter entails two pathways: (1) intrinsic pathway (contact activation pathway) and (2) extrinsic pathway (tissue factor pathway). Both pathways lead to the formation of fibrin.

Tissue factor is an integral membrane glycoprotein. It is made up of about 250 residues, with three distinct domains, i.e. extracellular, transmembrane, and cytoplasmic domains. It is encoded by the F3 gene. No associated genetic disorder has been identified with tissue factor. This clotting factor is expressed on the cell surface when there is an injury in blood vessels. It is produced by sub-endothelial cells and cells (e.g. fibroblasts) that surround blood vessels. It is also expressed on the surface of endothelial cells and monocytes when they become exposed to inflammatory molecules (e.g. TNF-alpha).

The tissue factor is involved in the initiation of thrombin formation. It has an affinity for the clotting factor VII (formerly known as proconvertin). The complex stimulates the initiation of the coagulation protease cascades.



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