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

We describe a PCR-based method for domain replacement that does not require restriction site sequences. We illustrate the technique in which the first epidermal growth factor (EGF1)-like domain of factor IX (FIX) is replaced by the EGF1-like domain of protein C. The method employs four oligonucleotide primers. Two are external primers (forward primer A and inverse primer B) and contain sequences flanking the FIX cDNA nucleotides. The other two primers (forward primer C and inverse primer D) direct the PCR amplification of the EGF1-like domain of protein C, and they are hybrid primers that contain sequences of protein C gene at the 3' end and of FIX gene at the 5' end. Thus the amplified fragment of EGF1-like domain of protein C (PCEGF1 fragment) is flanked by FIX gene sequences on both ends. When this fragment is mixed with FIX cDNA and subjected to one cycle of PCR, two products are obtained: one containing PCEGF1 fragment linked to FIX cDNA sequence upstream and the other containing PCEGF1 fragment linked to FIX cDNA sequence downstream of its EGF1-like domain. The first product is amplified using primers A and D, and the second product is amplified using primers B and C. Both products contain overlapping sequences, which allow annealing upon mixing. The annealed product is amplified by PCR using primers A and B. The final product contains FIX cDNA in which its EGF1 sequence has been replaced by the PCEGF1 sequence.
 ...
PMID:A PCR-based method for site-specific domain replacement that does not require restriction recognition sequences. 826 84

The cDNA encoding a chimeric human protein C (PC), in which its epidermal growth factor-(EGF) like regions have been replaced with equivalent structures from human factor IX (fIX), was constructed and the gene product was expressed in human 293 cells. A molecular subpopulation of the recombinant chimeric protein (r-[PC/delta EGF-1,2/delta fIXEGF-1,2]) was purified that contained the full complement (9 residues/mol) of gamma-carboxyglutamic acid (Gla). After conversion by thrombin to its activated form (r-[APC/delta EGF-1,2/delta fIXEGF-1,2]), this latter enzyme was found to possess approximately 10% of the activity of wild-type recombinant APC (wtr-APC) in an APTT assay. In assay systems employing purified components, the activity of the mutant enzyme toward prothrombinase cofactor Va (fVa) and tenase cofactor VIII (fVIII) was approximately 30% and < 10%, respectively, of that of wtr-APC. The chimeric protein displayed full reactivity with a Ca(2+)-dependent monoclonal antibody to the Gla domain of PC, yielding a C50 for Ca2+ that was very similar to that obtained with wtr-PC (ca. 3.7 mM). Titrations of the dependency on Ca2+ of the intrinsic fluorescence of r-[PC/delta EGF-1,2/delta fIXEGF-1,2] allowed calculation of a C50 value of 0.34 mM, again very similar to that of wtr-PC. As with wtr-PC, Ca2+ inhibited the thrombin-catalyzed activation of r-[PC/delta EGF-1,2/delta fIXEGF-1,2] with aKi of 148 microM, as compared to a Ki of 125 microM for wtr-PC. At a saturating level of Ca2+, activation of r-[PC/delta EGF-1,2/delta fIXEGF-1,2/] by the thrombin/thrombomodulin (thrombin/TM) complex occurred at approximately 70% of the rate of that of wtr-PC.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Construction, expression, and properties of a recombinant chimeric human protein C with replacement of its growth factor-like domains by those of human coagulation factor IX. 829 11

Methods for inactivating virus contaminants in serum, cryoprecipitate-poor plasma, and protein concentrates need to be identified. In this study, vesicular stomatitis virus (VSV)-spiked human serum and cryoprecipitate-poor plasma were treated with cross-linked povidone iodine (XLPVPI) at concentrations of 0, 4, 6, 8, and 10 mg/mL up to 120 min at 4 and 24 degrees C. The activities of virus and relevant proteins were examined. The results indicated that XLPVPI at concentrations that inactivate > 5 logs of VSV in serum decreased factor IX and protein C activities by < 10% in cryoprecipitate-poor plasma. At concentrations up to 10 mg of XLPVPI/mL, < 10% of protein C and factor IX activity was lost after incubation for 5 min at 24 degrees C. In addition, < 10% loss in protein C and factor IX activity was observed at 4 degrees C after treatment with < or = 6 mg of XLPVPI/mL for 20 min. Treatment of human serum with 6 mg of XLPVPI/mL at 4 degrees C and 8 mg of XLPVPI/mL at 24 degrees C for 5 min provided inactivation of > 5 logs of VSV.
 ...
PMID:Viral inactivation of vesicular stomatitis virus in normal human serum by cross-linked polyvinylpyrrolidone. 838 59

We report a quantitative protein C deficiency combined with a factor IX deficiency in a one-year-old boy. The inheritance of the two deficiency states was independent, the factor IX defect coming from the mother and the protein C defect from the father. Both factor IX activity and antigen were below 1%, and protein C activity as well as antigen were close to 27% of normal values. This association raises a real therapeutic and prognostic question. Protein C deficiency is indeed associated with a significant thrombotic risk and some factor IX concentrates seem to carry a potential thrombogenicity, particularly following infusion of repeated doses. We evaluated in this patient the potential activation of the coagulation system by measuring the levels of prothrombin fragment F1 + 2 at the basal state and after a single administration of 20 U/kg of a high purity factor IX concentrate. We found an unexpected basal activation of the hemostatic system before infusion (F1 + 2 = 1.6 nmol/L), which further increased during 8 hours. Despite the clinical predominant expression of the hemophilic trait, our results seem to assess the biologic prevalence of the protein C deficiency. This emphasizes the need for a careful follow-up after infusions of repeated doses of factor IX, as used during a surgical procedure. Furthermore, this raises the question of the prognosis because the risk of thrombotic manifestations associated with a protein C deficiency increases with age. Finally, these results highlight a part of the in vivo activation process of prothrombin in case of failure of the intrinsic pathway of coagulation. The protein C defect seems to be responsible for an upregulation of the prothrombin activation through the extrinsic pathway.
 ...
PMID:Increased thrombin generation in a child with a combined factor IX and protein C deficiency. 842 61

Hemostasis was assessed in 115 steady-state heart transplant recipients (HTRs) and compared with that of 23 age-matched healthy controls and 21 age-matched patients with ischemic heart disease (IHD). Compared with the controls, the HTRs had increased levels of fibrinogen (mean and 95% confidence limits of 4.50 [4.32-4.68] g/L versus 3.47 [3.07-3.87] g/L, P < 0.001), factor VIIC (1.16 [0.98-1.21] IU/ml versus 0.99 [0.89-1.10] IU/ml, P < 0.001), and von Willebrand factor antigen (1.72 [1.58-1.88] IU/ml versus 1.00 [0.80-1.26] IU/ml, P < 0.001). HTRs had increased antithrombin III activity (P = 0.002) and protein C activity (P = 0.002), with a decrease in total protein S levels (P < 0.001) but no change in free protein S levels. Stepwise discriminant analysis of hemostatic variables showed that fibrinogen was the best discriminator of the three groups, classifying 55.6% of HTR, 40% of IHD, and 66.7% of the controls. More marked prothrombotic changes were found in HTRs transplanted for IHD than for other causes; this reached significance for prothrombin (P = 0.048), factor IX (P = 0.003), and poor fibrinolytic activity as measured by euglobulin clot lysis time (P = 0.008). The HTRs with accelerated coronary sclerosis (ACS) tended to have the most prothrombotic changes; this reached significance with factor IX (P = 0.03). In conclusion, HTRs have perturbed hemostasis; the net effects of these changes are prothrombotic. The relationship between prothrombotic changes and ACS merits further studies.
 ...
PMID:Hemostatic changes in heart transplant recipients and their relationship to accelerated coronary sclerosis. 843 82

Clinical observations have added to the understanding of basic mechanisms of blood coagulation and its alterations in certain hemorrhagic and thrombotic states. Much clinical evidence exists for concluding that the exposure of blood to tissue factor (thromboplastin) on tissue cells represents the key event initiating fibrin clot formation after tissue injury. This then results in the formation of activated factor VII (VIIa)-tissue factor complexes, which must activate both factor X and factor IX for normal hemostasis. I describe the possible clinical consequences of an aberrant function of the natural anticoagulants regulating blood coagulation--antithrombin, protein C, and tissue factor pathway inhibitor. Understanding the physiologic function of tissue factor pathway inhibitor can illuminate why hemophilic patients bleed, but many other questions remain. I briefly review the four causes for acquired disorders of the blood coagulation reactions--vitamin K deficiency, hepatocellular disease, antibodies to clotting factors, and disseminated intravascular coagulation--but limit my comments to the mechanisms that trigger the formation of antibodies to clotting factors and how these antibodies can deplete the blood of clotting factor activities. Finally, heparin is able to potentiate tissue factor pathway inhibitor function, which is a possible reason why the use of heparin but not warfarin can prevent the numerous thrombotic episodes of the Trousseau's syndrome.
 ...
PMID:Blood coagulation and its alterations in hemorrhagic and thrombotic disorders. 843 80

Patients with hemophilia A and B and factor levels than 1 percent of normal bleed frequently with an average number of spontaneous bleeding episodes of 20-30 or more. However there are patients with equally low levels of factor VIII or factor IX who bleed once or twice per year or not at all. To examine whether the presence of a hereditary defect predisposing to hypercoagulability might play a role in ameliorating the hemorrhagic tendency in these so-called "mild severe" hemophiliacs, we determined the prevalence of prothrombotic defects in 17 patients with hemophilia A and four patients with hemophilia B selected from 295 and 76 individuals with these disorders, respectively, followed at a large Italian hemophilia center. We tested for the presence of the Factor V Leiden mutation by PCR-amplifying a fragment of the factor V gene which contains the mutation site and then digesting the product with the restriction enzyme MnlI. None of the patients with hemophilia A and only one patient with hemophilia B was heterozygous for Factor V Leiden. None of the 21 patients had hereditary deficiencies of antithrombin III, protein C, or protein S. Our results indicate that the milder bleeding diathesis that is occasionally seen among Italian hemophiliacs with factor levels that are less than 1 percent cannot be explained by the concomitant expression of a known prothrombotic defect.
 ...
PMID:Low prevalence of the factor V Leiden mutation among "severe" hemophiliacs with a "milder" bleeding diathesis. 860 5

Factor VIIa is a vitamin K-dependent enzyme whose gamma-carboxyglutamic acid (Gla)-containing domain is important for calcium ion-dependent binding to the cofactor tissue factor and membrane surfaces. This domain contains 10 Gla residues, the individual roles and importance of which are not known. Comparisons with the homologous protein C, factor IX and prothrombin may provide functional information on the first nine Gla residues, whereas no data can be extrapolated to Gla-35 in factor VIIa. Therefore, the effects of posttranslational gamma-carboxylation and site-directed mutagenesis of Glu-35 were investigated. Mutations to Asp, Gln or Val all lead to a lower affinity for tissue factor by decreasing the rate of association, in the case of the Val mutant by a factor of 200, as measured by surface plasmon resonance. In contrast, Glu or Gla side chains at position 35 appear to fulfil the functional roles equally well.
 ...
PMID:Site-directed mutagenesis but not gamma-carboxylation of Glu-35 in factor VIIa affects the association with tissue factor. 864 60

A model system for the analysis of intracellular events governing the modification of individual vitamin K-dependent (VKD) proteins by the carboxylase has been developed using recombinant VKD protein-transfected cell lines. When untransfected 293 cells were analyzed by in vitro carboxylation followed by SDS-PAGE, endogenous VKD proteins were not detected. With 293 cells stably-transfected with recombinant native factor IX, most (> 95%) of the carboxylase was in complex with the factor IX, as assayed by adsorption of carboxylase activity to immobilized anti-factor IX antibody. In contrast, with 293 cells stably-transfected with recombinant factor IX deleted in the propeptide sequence (amino acids -18 to -4, delta pro factor IX), no association of factor IX with the carboxylase was observed. This observation was used to specifically isolate and identify the human carboxylase, and carboxylase-associated protein. When the carboxylase was purified from solubilized microsomes from either native factor IX, or delta pro factor IX, stably-transfected 293 cells, a single 98 kDa band was specifically obtained from native factor IX microsomes, but not from delta pro factor IX microsomes. This band was subsequently shown by Western and microsequencing analysis to comprise both the carboxylase and carboxylase-associated protein. This isolation, which represents the first isolation to near homogeneity of both the human carboxylase and the carboxylase from cell lines, will be valuable in isolating enzymatically active recombinant carboxylase, which has been refractile to other purification attempts. This system was also used to show that the human carboxylase in 293 cells is capable of binding and modifying two different liver-derived proteins. Protein C-producing 293 cells were generated from the same 293 progenitor cell line used to created the factor IX-expressing cells. With both factor IX- and protein C-transfected 293 cells, the secreted proteins were almost completely carboxylated, and in microsomes from each cell line the carboxylase was found in near quantitative complex with the two different VKD proteins. Thus the carboxylase modifies both VKD proteins. The approach described here for the analysis of the carboxylase from recombinant VKD protein-transfected cell lines should provide an important new system for studying protein carboxylation and VKD protein-carboxylase interaction.
 ...
PMID:Isolation of the human gamma-carboxylase and a gamma-carboxylase-associated protein from factor IX-expressing mammalian cells. 867 78

We have demonstrated the presence of a saturable, reversible, and Ca(2+)-dependent binding site for 125I-labeled factor X ([125I]factor X) on human platelets (16000 +/- 2000 sites per platelet, Kd = 320 +/- 40 nM, n = 12) activated with either thrombin or the thrombin receptor agonist peptide, SFLLRN-amide, but not with ADP. Bound [125I]factor X could be completely removed by the addition of a Ca2+ chelator or an excess of unlabeled factor X. Antibodies that inhibit binding of factor X to the MAC-1 integrin receptor of monocytes and those directed against human factor V, failed to disrupt [125I]factor X binding to platelets. Prothrombin, but neither factor VII, factor IX, protein C, nor protein S, was an effective competitor of [125I]factor X binding with a K1 approximately Kd. [125I]Prothrombin also binds to activated (but not unactivated) platelets in a saturable, reversible, and Ca(2+)-dependent manner (20500 +/- 1500 sites, Kd = 470 +/- 110 nM, n = 3). Annexin V potently inhibited the binding of both [125I]factor X and [125I]prothrombin (IC50 approximately 3 nM). Factor X, prothrombin, and prothrombin fragment 1 (residues 1-155) were equipotent inhibitors of [125I]prothrombin and [125I]factor X binding, whereas Gla-domain-less factor X was unable to compete with [125I]factor X for platelet binding sites. Thus, it is the Gla-domains of factor X and prothrombin that appear to contain the regions necessary for platelet binding. The results of studies utilizing artificial phospholipid surfaces have led to the hypothesis that the substrates (FX and prothrombin) for the intrinsic pathway FXase and prothrombinase complexes are bound to the phospholipid surface. The factor X/prothrombin binding site we have described on the surface of activated platelets permits the utilization of surface-bound substrates by these complexes when they are assembled on a physiologic surface.
 ...
PMID:A binding site expressed on the surface of activated human platelets is shared by factor X and prothrombin. 868 25


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>