Factor X

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Coagulation factor X
PBB Protein F10 image.jpg
PDB rendering based on 1c5m.
Symbol(s) F10; FX; FXA
External IDs OMIM: 227600 MGI103107 Homologene30976
RNA expression pattern

PBB GE F10 205620 at tn.jpg

More reference expression data

Human Mouse
Entrez 2159 14058
Ensembl ENSG00000126218 ENSMUSG00000031444
Uniprot P00742 Q3TBR2
Refseq NM_000504 (mRNA)
NP_000495 (protein)
NM_007972 (mRNA)
NP_031998 (protein)
Location Chr 13: 112.83 - 112.85 Mb Chr 8: 13.04 - 13.06 Mb
Pubmed search [1] [2]

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Editors-In-Chief: John Alexander, M.D. [3], Duke Clinical Research Institute; C. Michael Gibson, M.S., M.D. Duke Clinical Research Institute [4]


Factor X, also known by the eponym Stuart-Prower factor or as thrombokinase, is an enzyme (EC of the coagulation cascade. It is a serine endopeptidase (protease group S1).


Factor X is synthesized in the liver and requires vitamin K for its synthesis.

Factor X is activated into factor Xa by both factor IX (with its cofactor, factor VIII in a complex known as intrinsic Xase) and factor VII with its cofactor, tissue factor (a complex known as extrinsic Xase). It is therefore the first member of the final common pathway or thrombin pathway.

It acts by cleaving prothrombin in two places (an arg-thr and then an arg-ile bond), which yields the active thrombin. This process is optimized when factor Xa is complexed with activated co-factor V in the prothrombinase complex.

Factor Xa is inactivated by protein Z-dependent protease inhibitor (ZPI), a serine protease inhibitor (serpin). The affinity of this protein for factor Xa is increased 1000-fold by the presence of protein Z, while it does not require protein Z for inactivation of factor XI. Defects in protein Z lead to increased factor Xa activity and a propensity for thrombosis.

The half life of factor X is 40-45 hours.


The human factor X gene is located on the thirteenth chromosome (13q34).

Role in disease

Inborn deficiency of factor X is very uncommon (1:500,000), and may present with epistaxis (nosebleeds), hemarthrosis (bleeding into joints) and gastrointestinal blood loss. Apart from congenital deficiency, low factor X levels may occur occasionally in a number of disease states.

Deficiency of vitamin K or antagonism by warfarin (or similar medication) leads to the production of an inactive factor X. In warfarin therapy, this is desirable to prevent thrombosis. As of late 2007, four out of five emerging anti-coagulation therapeutics targeted this enzyme.[1]

Therapeutic use

Factor X is not commercially available as a concentrate, but is part of fresh frozen plasma and prothrombin complex.

Use in Biochemistry

The Factor Xa protease can be used in biochemistry to cleave off protein tags that improve expression or purification of a protein of interest. Its preferred cleavage site (after the arginine in ile-glu/asp-gly-arg) can easily be engineered between a tag sequence and the protein of interest. After expression and purification, the tag is then proteolytically removed by Factor Xa.


American and British scientists described deficiency of factor X independently in 1953 and 1956, respectively. As with some other coagulation factors, the factor was initially named after these patients, a Mr Rufus Stuart and a Miss Audrey Prower.

External links


  1. Ron Winslow (2007-12-10). "Race Is on for the Next Blood Thinner". Wall Street Journal. p. A12. Retrieved 2008-01-06. The flurry of interest reflects increasing understanding of what doctors call the coagulation cascade... Four new blood thinners target an enzyme called factor Xa, one of several enzymes that play an important role in the cascade.  Unknown parameter |coauthors= ignored (help)

Further reading

  • Cooper DN, Millar DS, Wacey A; et al. (1997). "Inherited factor X deficiency: molecular genetics and pathophysiology.". Thromb. Haemost. 78 (1): 161–72. PMID 9198147. 
  • Hassan HJ, Leonardi A, Chelucci C; et al. (1990). "Blood coagulation factors in human embryonic-fetal development: preferential expression of the FVII/tissue factor pathway.". Blood. 76 (6): 1158–64. PMID 1698100. 
  • Messier TL, Pittman DD, Long GL; et al. (1991). "Cloning and expression in COS-1 cells of a full-length cDNA encoding human coagulation factor X.". Gene. 99 (2): 291–4. PMID 1902434. 
  • Krishnaswamy S (1990). "Prothrombinase complex assembly. Contributions of protein-protein and protein-membrane interactions toward complex formation.". J. Biol. Chem. 265 (7): 3708–18. PMID 2303476. 
  • España F, Berrettini M, Griffin JH (1989). "Purification and characterization of plasma protein C inhibitor.". Thromb. Res. 55 (3): 369–84. PMID 2551064. 
  • Fung MR, Hay CW, MacGillivray RT (1985). "Characterization of an almost full-length cDNA coding for human blood coagulation factor X.". Proc. Natl. Acad. Sci. U.S.A. 82 (11): 3591–5. PMID 2582420. 
  • Jagadeeswaran P, Reddy SV, Rao KJ; et al. (1990). "Cloning and characterization of the 5' end (exon 1) of the gene encoding human factor X.". Gene. 84 (2): 517–9. PMID 2612918. 
  • Reddy SV, Zhou ZQ, Rao KJ; et al. (1989). "Molecular characterization of human factor XSan Antonio.". Blood. 74 (5): 1486–90. PMID 2790181. 
  • Kaul RK, Hildebrand B, Roberts S, Jagadeeswaran P (1986). "Isolation and characterization of human blood-coagulation factor X cDNA.". Gene. 41 (2-3): 311–4. PMID 3011603. 
  • Broze GJ, Warren LA, Novotny WF; et al. (1988). "The lipoprotein-associated coagulation inhibitor that inhibits the factor VII-tissue factor complex also inhibits factor Xa: insight into its possible mechanism of action.". Blood. 71 (2): 335–43. PMID 3422166. 
  • Gilgenkrantz S, Briquel ME, André E; et al. (1986). "Structural genes of coagulation factors VII and X located on 13q34.". Ann. Genet. 29 (1): 32–5. PMID 3487272. 
  • Leytus SP, Foster DC, Kurachi K, Davie EW (1986). "Gene for human factor X: a blood coagulation factor whose gene organization is essentially identical with that of factor IX and protein C.". Biochemistry. 25 (18): 5098–102. PMID 3768336. 
  • Leytus SP, Chung DW, Kisiel W; et al. (1984). "Characterization of a cDNA coding for human factor X.". Proc. Natl. Acad. Sci. U.S.A. 81 (12): 3699–702. PMID 6587384. 
  • McMullen BA, Fujikawa K, Kisiel W; et al. (1983). "Complete amino acid sequence of the light chain of human blood coagulation factor X: evidence for identification of residue 63 as beta-hydroxyaspartic acid.". Biochemistry. 22 (12): 2875–84. PMID 6871167. 
  • Marchetti G, Castaman G, Pinotti M; et al. (1995). "Molecular bases of CRM+ factor X deficiency: a frequent mutation (Ser334Pro) in the catalytic domain and a substitution (Glu102Lys) in the second EGF-like domain.". Br. J. Haematol. 90 (4): 910–5. PMID 7669671. 
  • Morgenstern KA, Sprecher C, Holth L; et al. (1994). "Complementary DNA cloning and kinetic characterization of a novel intracellular serine proteinase inhibitor: mechanism of action with trypsin and factor Xa as model proteinases.". Biochemistry. 33 (11): 3432–41. PMID 8136380. 
  • Heeb MJ, Rosing J, Bakker HM; et al. (1994). "Protein S binds to and inhibits factor Xa.". Proc. Natl. Acad. Sci. U.S.A. 91 (7): 2728–32. PMID 8146182. 
  • Inoue K, Morita T (1993). "Identification of O-linked oligosaccharide chains in the activation peptides of blood coagulation factor X. The role of the carbohydrate moieties in the activation of factor X.". Eur. J. Biochem. 218 (1): 153–63. PMID 8243461. 
  • Padmanabhan K, Padmanabhan KP, Tulinsky A; et al. (1993). "Structure of human des(1-45) factor Xa at 2.2 A resolution.". J. Mol. Biol. 232 (3): 947–66. PMID 8355279. doi:10.1006/jmbi.1993.1441. 
  • Sinha U, Wolf DL (1993). "Carbohydrate residues modulate the activation of coagulation factor X.". J. Biol. Chem. 268 (5): 3048–51. PMID 8428982.