In coagulation, the procoagulant protein factor X can be activated into factor Xa in two ways: either extrinsically or intrinsically. The activating complexes are together called tenase. Tenase is a

blend word In linguistics, a blend (sometimes called blend word, lexical blend, portmanteau or portmanteau word) is a word formed from parts of two or more other words. At least one of these parts is not a morph (the realization of a morpheme) but instead ...

of "ten" and the suffix "-ase", which means, that the complex activates its substrate (inactive factor X) by cleaving it. Extrinsic tenase complex is made up of

tissue factor Tissue factor, also called platelet tissue factor, factor III, or CD142, is a protein encoded by the ''F3'' gene, present in subendothelial tissue and leukocytes. Its role in the clotting process is the initiation of thrombin formation from the ...

, factor VII, and Ca²⁺ as an activating ion. Intrinsic tenase complex contains the active factor IX (IXa), its cofactor factor VIII (VIIIa), the substrate (factor X), and they are activated by negatively charged surfaces (such as glass, active platelet membrane, sometimes cell membrane of

monocytes Monocytes are a type of leukocyte or white blood cell. They are the largest type of leukocyte in blood and can differentiate into macrophages and conventional dendritic cells. As a part of the vertebrate innate immune system monocytes also infl ...

). These vitamin K-dependent procoagulant factors dock to this surface through their Gla domain with Ca²⁺ bridges.

References

{{Reflist Coagulation system