Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.30.2 (endonuclease)
 18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Binding interactions between the membrane-associated vitamin K-dependent carboxylase and its prothrombin and factor X substrates have been investigated in liver microsomes. Both substrates are firmly attached to microsomal membrane fragments which also harbor the carboxylase. In vitro 14CO2 gamma-carboxylation of these substrates, triggered by reduced vitamin K1H2, resulted in release of 14C-labeled prothrombin precursors from the membrane fragments, but no release of 14C-labeled factor X precursors could be demonstrated, which suggested a difference in early processing of these substrates by the carboxylase. Warfarin treatment of rats resulted in a 3-fold increase in the membrane concentration of factor X antigens and a 20-fold increase in 14C gamma-carboxylation of the membrane pool of factor X carboxylase substrates. There was a dose-response relationship between the amount of drug administered to the rats and 14C labeling of the membrane pool of factor X carboxylase substrates. On the other hand, the membrane concentration of prothrombin antigens did not increase in response to the drug, and 14CO2 gamma-carboxylation of the membrane pool of prothrombin carboxylase substrates was the same in warfarin and saline-treated rats. The results demonstrate significant differences in the interaction between the carboxylase and its prothrombin and factor X substrates. It appears that the different interactions result from binding of the prothrombin and the factor X precursors to separate microsomal membrane proteins that are involved in the gamma-carboxylation reaction. Warfarin appears to induce the factor X precursor-specific but not the prothrombin precursor-specific binding proteins, which suggests a new mechanism for the action of warfarin. These binding proteins may be under different genetic control. Treatment of the prothrombin and the factor X carboxylase substrates with endonuclease H showed that the rat prothrombin and the human factor X carboxylase substrates are high mannose glycoproteins. The human prothrombin and the rat factor X carboxylase substrates did not, on the other hand, change their migration in sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels after endonuclease H treatment. The data demonstrate differences in the glycoprotein nature of the rat and the human carboxylase substrates.
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PMID:Early processing of prothrombin and factor X by the vitamin K-dependent carboxylase. 329 Feb 18

Resistance to the anticoagulant effects of activated protein C (APC) is now considered the most prevalent cause of inherited thrombophilia. The great majority of patients with activated protein C resistance (APCR) have a missense mutation in the factor V molecule (factor V Leiden, FVR506Q) resulting in defective inactivation of factor Va due to a loss of an APC cleavage site. The diagnosis of APCR has been based upon the inability of APC to prolong the activated partial thromboplastin (aPTT) clotting time in subjects with APCR. However, this assay has a number of deficiencies which limit its general use. We have evaluated a newly described one-stage tissue factor dependent factor V coagulation assay for APCR in 117 patients and controls and compared the results of this assay in a blinded manner to a polymerase chain reaction (PCR) based assay for the molecular defect of factor V Leiden. 43% (50/117) of the patients studied were receiving coumadin or heparin, or had a lupus anticoagulant. The tissue factor dependent factor V assay had 100% specificity and sensitivity for factor V Leiden and successfully predicted a homozygous state in the three documented homozygotes. The PCR-based assay for factor V Leiden resulted in a single false positive assay due to a silent A to C transition at nucleotide 1692 resulting in the loss of the Mnl restriction endonuclease cleavage site. The single-stage tissue factor dependent factor V assay is a highly sensitive and generally applicable assay for APCR.
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PMID:Evaluation of a tissue factor dependent factor V assay to detect factor V Leiden: demonstration of high sensitivity and specificity for a generally applicable assay for activated protein C resistance. 894

Deep vein thrombosis (DVT) is a life-threatening disease. Warfarin and acenocoumarol are anticoagulants used to treat DVT and vary among individuals in terms of treatment response/toxicity. Single nucleotide polymorphisms (SNPs) in CYP2C9 and VKORC1 play a role in the pharmacokinetics and dynamics of warfarin and acenocoumarol and they determine the efficacy of treatment by controlling drug clearance in treated individuals. The aim of the current study was to genotype the critical SNPs of CYP2C9 and VKORC1 genes in a south Indian population in order to understand the metabolizer phenotype of patients with DVT. CYP2C9 (rs1799853, rs1057910, rs1057909, rs28371686) and VKORC1 (rs9923231) SNPs were genotyped in 124 cases of DVT. Genomic regions of these SNPs from genomic DNA were amplified with PCR and directly sequenced using Sanger sequencing except for the SNP rs1799853, which was detected using Sau96I restriction endonuclease-based digestion of variant alleles. Among south Indian patients with DVT, 6.5% (8/124) had the rs1799853 SNP of CYP2C9 and 11% (14/124) had the rs1057910 SNP while 16% (20/124) had the rs9923231 SNP of VKORC1 which were associated with the response to warfarin treatment. None of the patients tested positive for poor drug metabolizing genotypes of the CYP2C9 gene and only 1.6% of the south Indian population was sensitive to warfarin treatment. Genotyping results suggest that a relatively greater amount of the therapeutic drug is required to achieve/maintain the international normalized ratio (INR) in south Indian patients with DVT.
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PMID:Genotyping of CYP2C9 and VKORC1 polymorphisms predicts south Indian patients with deep vein thrombosis as fast metabolizers of warfarin/acenocoumarin. 2886 52