Protein C Inhibitor (PCI, also called PAI-3), human
Description of Protein C Inhibitor (PCI)
Protein C Inhibitor (PCI), also known as Plasminogen Activator Inhibitor 3 (PAI3), is a member of the SERPIN family of proteinase inhibitors. It is produced in the liver as a single chain glycoprotein (mass of 57 kDa) and circulates in plasma at a concentration of 5 ÃŽÂ¼g/ml (~90 nM). PCI is also found in urine in lower concentrations of 250 ng/mL (~0.4 nM).Ã‚Â PCI is the primary inhibitor of activated Protein C (APC) in plasma but demonstrates a relatively broad specificity, also inhibiting thrombin, FXa, FXIa, kallikrein, tPA, urokinase, prostate specific antigen, acrosin, chymotrypsin and trypsin. The preferred enzyme target for PCI appears to be thrombin and this interaction is increased by more than 100 fold in the presence of thrombomodulin. Like ATIII and HCII, the inhibitory activity of PCI towards some of these enzymes is stimulated by high concentrations of heparin (5 U/ml) which can accelerate the rate of inactivation as much as 50 fold. Enzyme inhibition by PCI occurs through proteolytic cleavage at Arg354-Ser355 and subsequent rapid formation of a stable, inactive 1:1 enzyme-PCI complex. Interaction with APC results in an SDS-stable APC-PCI complex of 102 kDa.1-4.
1. Suzuki K; Protein C Inhibitor; Methods in Enzymology 222, pp 385-399, 1993.
2. Cooper ST, Whinna HC, Jackson TP, Boyd JM, Church FC; Intermolecular Interactions between Protein C Inhibitor and Coagulation Proteases; Biochemistry: 34, pp. 12991-12997, 1995.
3. Heeb MJ, Espana F, Geiger M, Collen D, Stump DC, Griffin JH; Immunological Identity of Heparin-dependent Plasma & Urinary Protein C Inhibitor & Plasminogen Activator Inhibitor-3; JBC:262, pp 15813-15816, 1987.
4. Rezaie AR, Copper ST, Church FC, Esmon CT; Protein C Inhibitor is a Potent Inhibitor of the Thrombin-Thrombomodulin Complex; JBC:270, pp 25336-25339, 1995.
GAPCI-AP Goat anti-human Protein C Inhibitor, affinity purified IgG
GAPCI-HRP Goat anti-human Protein C Inhibitor, IgG-peroxidase
PCI-EIA Paired antibody set for ELISA of PCI, 5 x 96 wells
APCPCI-EIA Paired antibody ELISA of APC-PCI complex, 5 x 96 wells