Factor XI

Source: Wikipedia, the free encyclopedia.
F11
Gene ontology
Molecular function
Cellular component
Biological process
Sources:Amigo / QuickGO
Ensembl
UniProt
RefSeq (mRNA)

NM_000128
NM_019559
NM_001354804

NM_028066

RefSeq (protein)

NP_000119
NP_001341733

NP_082342

Location (UCSC)Chr 4: 186.27 – 186.29 MbChr 8: 45.69 – 45.72 Mb
PubMed search[3][4]
Wikidata
View/Edit HumanView/Edit Mouse

Factor XI or plasma thromboplastin antecedent is the zymogen form of factor XIa, one of the enzymes of the coagulation cascade. Like many other coagulation factors, it is a serine protease. In humans, Factor XI is encoded by the F11 gene.[5][6][7][8]

Function

Factor XI (FXI) is produced by the

HMWK, prekallikrein, factor XII, factor XI, and factor IX).[10]

Factor XIa activates factor IX by selectively cleaving arg-ala and arg-val peptide bonds. Factor IXa, in turn, forms a complex with Factor VIIIa (FIXa-FVIIIa) and activates factor X.

Physiological inhibitors of factor XIa include

serine protease inhibitor/serpin class of proteins), which is independent of protein Z
(its action on factor X, however, is protein Z-dependent, hence its name).

Structure

Although synthesized as a single polypeptide chain, FXI circulates as a homodimer. Every chain has a relative molecular mass of approximately 80000. Typical plasma concentrations of FXI are 5 μg/mL, corresponding to a plasma concentration (of FXI dimers) of approximately 30 nM. The FXI gene is 23kb in length, has 15 exons, and is found on chromosome 4q32-35.[6][7]

Factor XI consists of four apple domains, that create a disk-like platform around the base of a fifth, catalytic serine protease domain. One contains a binding site for

disulfide bond
.

In the homodimer, the apple domains create two disk-like platforms connected together at an angle, with the catalytic domains sticking out at each side of the dimer.

Activation by thrombin or factor XIIa is achieved by cleavage of Arg369-Ile370 peptide bonds on both subunits of the dimer. This results in a partial detachment of the catalytic domain from the disk-like apple domains, still linked to the fourth domain with a disulfide bond, but now farther from the third domain. This is thought that this exposes the factor IX binding site of the third apple domain, allowing factor XI's protease activity on it. [11]

Role in disease

Deficiency of factor XI causes the rare

autosomal recessive disorder. There is little spontaneous bleeding, but surgical procedures may cause excessive blood loss, and prophylaxis is required.[12]

Low levels of factor XI also occur in many other disease states, including Noonan syndrome.

High levels of factor XI have been implicated in thrombosis, although it is uncertain what determines these levels and how serious the procoagulant state is.

Pharmacological inhibitors of factor XI that are under clinical development but not yet approved for treatment as of May 2022 include the oral factor XIa inhibitors Asundexian (BAY 2433334)[13] and Milvexian[14] as well as the monoclonal anti-factor XI antibody Abelacimab (MAA868).[15]

See also

  • Contact activation pathway
    (also known as the intrinsic pathway)
  • Tissue factor pathway
    (also known as the extrinsic pathway)

References

  1. ^ a b c GRCh38: Ensembl release 89: ENSG00000088926Ensembl, May 2017
  2. ^ a b c GRCm38: Ensembl release 89: ENSMUSG00000031645Ensembl, May 2017
  3. ^ "Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
  4. ^ "Mouse PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
  5. PMID 3636155
    .
  6. ^ .
  7. ^ .
  8. .
  9. .
  10. S2CID 32572142. Archived from the original
    on 2016-04-16. Retrieved 2009-01-07.
  11. .
  12. .
  13. ^ Clinical trial number NCT04304508 for "Study to Gather Information About Proper Dosing and Safety of the Oral FXIa Inhibitor BAY 2433334 in Patients Following a Recent Non Cardioembolic Ischemic Stroke Which Occurs When a Blood Clot Has Formed Somewhere in the Human Body (But Not in the Heart) Travelled to the Brain. (PACIFIC-STROKE)" at ClinicalTrials.gov
  14. S2CID 244132392
    .
  15. .

Further reading

External links