Protein Z-related protease inhibitor

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Crystal structure of protein Z-dependent peptidase inhibitor (red) in complex with protein Z (blue). Rendered from PDB 3F1S
Other data
LocusChr. 14 q32.1

Protein Z-dependent protease inhibitor is a protein circulating in the blood which inhibits factors Xa and XIa of the coagulation cascade. It is a member of the class of the serine protease inhibitors (serpins). Its name implies that it requires protein Z, another circulating protein, to function properly, but this only applies to its inhibition of factor X.

It is about 72 kDa heavy and 444 amino acids large. It is produced by the liver.

Role in disease

Water et al. found deficiency of ZPI in 4.4% of a cohort of patients with thrombophilia (a tendency to thrombosis).[1]


Han et al. first described ZPI in 1998.[2] The same group further characterised it in 2000.[3]


  1. Van de Water N, Tan T, Ashton F, O'Grady A, Day T, Browett P, Ockelford P, Harper P (October 2004). "Mutations within the protein Z-dependent protease inhibitor gene are associated with venous thromboembolic disease: a new form of thrombophilia". British Journal of Haematology. 127 (2): 190–4. doi:10.1111/j.1365-2141.2004.05189.x. PMID 15461625.
  2. Han X, Fiehler R, Broze GJ (August 1998). "Isolation of a protein Z-dependent plasma protease inhibitor". Proceedings of the National Academy of Sciences of the United States of America. 95 (16): 9250–5. PMC 21324. PMID 9689066.
  3. Han X, Fiehler R, Broze GJ (November 2000). "Characterization of the protein Z-dependent protease inhibitor". Blood. 96 (9): 3049–55. PMID 11049983.

External links

  • The MEROPS online database for peptidases and their inhibitors: I04.005