Coagulation Factor X is a vitamin K-dependent plasma protease that activates thrombin in blood coagulation. Initially synthesized in the liver as a single-chain precursor, factor X is activated by both the intrinsic and extrinsic pathways to Xa, which consists of disulfide bond-linked light and heavy chains. The light chain contains a Gla and two EGF-like domains and the heavy chain corresponds to the serine protease domain.