[PROC_HUMAN] Defects in PROC are the cause of thrombophilia due to protein C deficiency, autosomal dominant (THPH3) [MIM:176860]. A hemostatic disorder characterized by impaired regulation of blood coagulation and a tendency to recurrent venous thrombosis. However, many adults with heterozygous disease may be asymptomatic. Individuals with decreased amounts of protein C are classically referred to as having type I protein C deficiency and those with normal amounts of a functionally defective protein as having type II deficiency. Defects in PROC are the cause of thrombophilia due to protein C deficiency, autosomal recessive (THPH4) [MIM:612304]. A hemostatic disorder characterized by impaired regulation of blood coagulation and a tendency to recurrent venous thrombosis. It results in a thrombotic condition that can manifest as a severe neonatal disorder or as a milder disorder with late-onset thrombophilia. The severe form leads to neonatal death through massive neonatal venous thrombosis. Often associated with ecchymotic skin lesions which can turn necrotic called purpura fulminans, this disorder is very rare.
[EPCR_HUMAN] Binds activated protein C. Enhances protein C activation by the thrombin-thrombomodulin complex; plays a role in the protein C pathway controlling blood coagulation. [PROC_HUMAN] Protein C is a vitamin K-dependent serine protease that regulates blood coagulation by inactivating factors Va and VIIIa in the presence of calcium ions and phospholipids.
The endothelial cell protein C receptor (EPCR) shares approximately 20% sequence identity with the major histocompatibility complex class 1/CD1 family of molecules, accelerates the thrombin-thrombomodulin-dependent generation of activated protein C, a natural anticoagulant, binds to activated neutrophils, and can undergo translocation from the plasma membrane to the nucleus. Blocking protein C/activated protein C binding to the receptor inhibits not only protein C activation but the ability of the host to respond appropriately to bacterial challenge, exacerbating both the coagulant and inflammatory responses. To understand how EPCR accomplishes these multiple tasks, we solved the crystal structure of EPCR alone and in complex with the phospholipid binding domain of protein C. The structures were strikingly similar to CD1d. A tightly bound phospholipid resides in the groove typically involved in antigen presentation. The protein C binding site is outside this conserved groove and is distal from the membrane-spanning domain. Extraction of the lipid resulted in loss of protein C binding, which could be restored by lipid reconstitution. CD1d augments the immune response by presenting glycolipid antigens. The EPCR structure is a model for how CD1d binds lipids and further suggests additional potential functions for EPCR in immune regulation, possibly including the anti-phospholipid syndrome.
The crystal structure of the endothelial protein C receptor and a bound phospholipid.,Oganesyan V, Oganesyan N, Terzyan S, Qu D, Dauter Z, Esmon NL, Esmon CT J Biol Chem. 2002 Jul 12;277(28):24851-4. Epub 2002 May 28. PMID:12034704
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
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↑ Oganesyan V, Oganesyan N, Terzyan S, Qu D, Dauter Z, Esmon NL, Esmon CT. The crystal structure of the endothelial protein C receptor and a bound phospholipid. J Biol Chem. 2002 Jul 12;277(28):24851-4. Epub 2002 May 28. PMID:12034704 doi:http://dx.doi.org/10.1074/jbc.C200163200