– Mouse coagulation factor X / F10 a member of the peptidase S1 family. The mature F10 is composed mostly of two EGF-like domains, one Gla gamma-carboxy-glutamate domain and one peptidase S1 domain. Factor Xa is a vitamin K-dependent plasma protease that converts prothrombin to thrombin in the presence of factor Va, calcium and phospholipid during blood clotting. The two chains of F10 are formed from a single-chain precursor by the excision of two Arg residues. A single-chain precursor is initially synthesized in the liver. The light and heavy chains are linked together by disulfide bonds. The light chain contains a Gla and two EGF-like domains. The heavy chain corresponds to the serine protease domain. It can form a heterodimer with SERPINA5.