Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.21.69 (APC)
 16,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Thrombomodulin is an endothelial cell membrane protein which plays a central regulatory role in the protein C anticoagulant pathway. The human thrombomodulin intronless gene was isolated from a genomic DNA library and used to isolate the coding region. A mammalian expression vector, phd-TMD1, encoding all the extracellular domains of human thrombomodulin but lacking the transmembrane and cytoplasmic domains was constructed. Stable phd-TMD 1 transformants, in both hamster AV12-644 and human 293 cells, expressed functionally active recombinant thrombomodulin as a secreted, soluble product. Soluble thrombomodulin was secreted as two major proteins of 105 kDa and 75 kDa, both of which were purified to homogeneity. The kinetic properties for protein C activation of the two proteins were very different: the Kd for thrombin, Km for protein C, and Ca2+ optima were 3.0 nM, 1.5 microM, and 1-3 mM for the 105-kDa protein and 16 nM, 2.3 microM, and 0.2-0.5 mM for the 75-kDa protein. In clotting and platelet activation assays, the 105-kDa protein was a much more potent anticoagulant than the 75-kDa protein. Both forms of the protein had the amino-terminal sequence Ala19-Pro-Ala-Glu-Pro-Gln. Amino acid composition analysis indicated that both forms of the protein had the same amino acid content which was consistent with the predicted protein comprising residues Ala19 to Ser515. The difference in size appeared to be due to glycosylation as both forms were of similar size following chemical deglycosylation. These studies suggest that (1) secretable thrombomodulin derivatives can be used to study structure-function relationships of the extracellular domains of this important regulatory protein, (2) the extent of glycosylation has profound effects on the kinetic and anticoagulant properties of human thrombomodulin, and (3) soluble recombinant human thrombomodulins may be developed as clinically significant therapeutic anticoagulants.
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PMID:Stable expression of a secretable deletion mutant of recombinant human thrombomodulin in mammalian cells. 216 69

Thromboembolism is a prominent but poorly understood feature of eosinophilic, or Loeffler's endocarditis. Eosinophil (EO) specific granule proteins, in particular major basic protein (MBP), accumulate on endocardial surfaces in the course of this disease. We hypothesized that these unusually cationic proteins promote thrombosis by binding to the anionic endothelial protein thrombomodulin (TM) and impairing its anticoagulant activities. We find that MBP potently (IC50 of 1-2 microM) inhibits the capacity of endothelial cell surface TM to generate the natural anticoagulant activated protein C (APC). MBP also inhibits APC generation by purified soluble rabbit TM with an IC50 of 100 nM without altering its apparent Kd for thrombin or Km for protein C. This inhibition is reversed by polyanions such as chondroitin sulfate E and heparin. A TM polypeptide fragment comprising the extracellular domain that includes its naturally occurring anionic glycosaminoglycan (GAG) moiety (TMD-105) is strongly inhibited by MBP, whereas its counterpart lacking the GAG moiety (TMD-75) is not. MBP also curtails the capacity of TMD-105 but not TMD-75 to prolong the thrombin clotting time. Thus, EO cationic proteins potently inhibit anticoagulant activities of the glycosylated form of TM, thereby suggesting a potential mechanism for thromboembolism in hypereosinophilic heart disease.
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PMID:Eosinophil cationic granule proteins impair thrombomodulin function. A potential mechanism for thromboembolism in hypereosinophilic heart disease. 838 94

Different immunosuppressive agents, in particular OKT3, have been implicated as causative factors in the risk for renal thrombosis in the period immediately after kidney transplantation. Also, in different types of vascular surgery, a state similar to hypercoagulation has been reported. To assess the extent to which OKT3, cyclosporine A (CsA), and surgery itself affect coagulation and fibrinolysis, a study was conducted of 20 patients divided into two groups: group A, 10 patients received OKT3 (first dose during the induction of anesthesia); and group B, 10 patients received CsA (first dose at least 2 hours before transplantation). Basal determinations and determinations at 2, 4, and 24 hours after the induction of anesthesia were made. No differences were found between the groups with respect to the clinical and usual coagulation parameters. The following were studied in both groups: (1) markers of coagulation activity (prekallikrein [PKK] levels and formation of thrombin-antithrombin complexes [TATc]), (2) inhibitors and suppressors of hemostasis (antithrombin III [AT-III] and protein C [PC] activity), (3) markers of fibrinolysis activation (levels of plasminogen [PLG] and of alpha2-antiplasmin [alpha2-APL]), and (4) markers of endothelial damage (tissue plasminogen activator [TPA] and thrombomodulin [TMD]). In both groups, an important formation of TATc was observed early, together with a decrease in PKK levels and consumption of both AT-III and PC, which reached their lowest levels at 24 hours. This points to an activation of coagulation through the intrinsic route and a secondary consumption of hemostasis inhibitors, both possibly caused by surgery. A consumption of PLG and alpha2-APL was also observed, reflecting stimulation of the fibrinolytic system and a physiological response to the activation of coagulation. A greater release of endothelial TPA was only observed in the patients receiving OKT3 (P < 0.0001), possibly signaling endothelial activation. It is concluded that surgical stress could be the major factor triggering the alterations seen in hemostasis and their possible consequences.
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PMID:Changes in coagulation and fibrinolysis in the postoperative period immediately after kidney transplantation in patients receiving OKT3 or cyclosporine A as induction therapy. 977 17