Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.21.68 (tissue plasminogen activator)
 11,311 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Proteins of the serpin family (serine protease inhibitor) control key steps in the inflammatory, coagulation and complement systems. C1-inhibitor deficiency predisposes to hereditary angioneurotic oedema, and other serpins control proteolytic enzymes that may cause complement activation or the forming of oedema. We investigated whether deficiency of proteins of the serpin family may predispose to cold urticaria and therefore screened 7 male patients with severe cold urticaria for the presence of deficiency alleles of some of the members of the serpin antiprotease family. There were no findings of C1-inhibitor, alpha 1-antitrypsin, alpha 2-antiplasmin, antithrombin III, tissue plasminogen activator inhibitor or thyroxine binding protein deficiency. The prevalence of heterozygous alpha 1-antichymotrypsin deficiency was significantly higher than expected (prevalence ratio 25.8 (95% confidence interval 6.0-112), p < 0.0001). This finding is in concert with previous studies that have shown lower mean levels of alpha 1-antichymotrypsin among patients with cold urticaria and suggests that heterozygous deficiency of this antiprotease, which controls neutrophil cathepsin G and mast cell chymase may predispose to cold urticaria. The present series is, however, small and the results need confirmation in larger materials.
 ...
PMID:Heterozygous alpha 1-antichymotrypsin deficiency may be associated with cold urticaria. 148 47

Plasminogen activator inhibitor-1 (PAI-1) is a specific inhibitor of the serine proteases tissue-type plasminogen activator (tPA) and urokinase-type plasminogen activator (uPA). To systematically investigate the roles of the reactive center P1 and P1' residues in PAI-1 function, saturation mutagenesis was utilized to construct a library of PAI-1 variants. Examination of 177 unique recombinant proteins indicated that a basic residue was required at P1 for significant inhibitory activity toward uPA, whereas all substitutions except proline were tolerated at P1'. P1Lys variants exhibited lower inhibition rate constants and greater sensitivity to P1' substitutions than P1Arg variants. Alterations at either P1 or P1' generally had a larger effect on the inhibition of tPA. A number of variants that were relatively specific for either uPA or tPA were identified. P1Lys-P1'Ala reacted 40-fold more rapidly with uPA than tPA, whereas P1Lys-P1'Trp showed a 6.5-fold preference for tPA. P1-P1' variants containing additional mutations near the reactive center demonstrated only minor changes in activity, suggesting that specific amino acids in this region do not contribute significantly to PAI-1 function. These findings have important implications for the role of reactive center residues in determining serine protease inhibitor (serpin) function and target specificity.
 ...
PMID:Saturation mutagenesis of the plasminogen activator inhibitor-1 reactive center. 155 96

The endothelial cells (ECs) are antithrombotic in the physiological states and maintains the integrity of blood circulation. However, ECs turn to be thrombotic upon being stimulated by various physiological mediators. These functions are mainly achieved by changing specific protein synthesis in ECs. Type 1 plasminogen activator inhibitor (PAI-1) is a serine protease inhibitor synthesized by ECs and thought to play a crucial role in the regulation of fibrinolysis. Basic research as well as clinical studies support this hypothesis. PAI-1 is a physiological inhibitor of both tissue-type plasminogen activator and urokinase-type plasminogen activator, key enzymes in the initiation of fibrinolysis. Thus PAI-1 regulates not only blood clot lysis but also a wide variety of biological reactions occurring in extracellular matrices such as tumor metastasis, neovascularization, inflammation, and cell migration. PAI-1 is a glycoprotein, of which molecular weight is approximately 50,000. Molecular biological analyses indicate that PAI-1 is synthesized as a single polypeptide composed of 402 amino acids containing a signal peptide. After post-translational modification, PAI-1 is secreted from ECs as a polypeptide composed of 379 amino acids and three N-linked carbohydrates. PAI-1 lacks Cys residues, indicating that PAI-1 may not be rigid and thus thermolabile. In fact, PAI-1 is unstable even at 37 degrees C decaying into an inactive form with a biological half life of 2-3 hours. PAI-1 binds to a cell adhesion molecule, vitronectin. The association of PAI-1 with vitronectin appears to stabilize PAI-1. PAI-1 in complex with vitronectin is still accessible to plasminogen activators.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:[Type 1 plasminogen activator inhibitor: its role in biological reactions]. 187 Feb 65

Fibrinolysis is regulated in part by the interaction between tissue-type plasminogen activator (t-PA) and plasminogen activator inhibitor 1 (PAI-1, a serine protease inhibitor of the serpin family). It is known from our earlier work that deletion of a loop of amino acids (residues 296-302) from the serine protease domain of t-PA suppresses the interaction between the two proteins without altering the reactivity of t-PA towards its substrate, plasminogen. To define more precisely the role of individual residues within this loop, we have used site-directed mutagenesis to replace Lys-296, Arg-298, and Arg-299 with negatively charged glutamic residues. Replacement of all three positively charged amino acids generates a variant of t-PA that associates inefficiently with PAI-1 and is highly resistant to inhibition by the serpin. Two t-PAs with point mutations (Arg-298----Glu and Arg-299----Glu) are partially resistant to inhibition by PAI-1 and associate with the serpin at intermediate rates. Other point mutations (Lys-296----Glu, His-297----Glu, and Pro-301----Gly) do not detectably affect the interaction of t-PA with PAI-1. None of these substitutions has a significant effect on the rate of catalysis by t-PA or on the affinity of the enzyme for its substrate, plasminogen. On the basis of these results, we propose a model in which positively charged residues located in a surface loop near the active site of t-PA form ionic bonds with complementary negatively charged residues C-terminal to the reactive center of PAI-1.
 ...
PMID:Amino acid residues that affect interaction of tissue-type plasminogen activator with plasminogen activator inhibitor 1. 211 Mar 66

A low molecular weight serine protease inhibitor (TAP) was purified from extracts of the soft tick, Ornithodoros moubata. The peptide is a slow, tight-binding inhibitor, specific for factor Xa (Ki = 0.588 +/- 0.054 nM). The inhibitor also acts as an anticoagulant in several human plasma clotting assays in vitro. Its amino acid sequence (60 residues) has limited homology to the Kunitz-type inhibitors. However, unlike other inhibitors of this class, TAP inhibits only factor Xa. It had no effect at a 300-fold molar excess on factor VIIa, kallikrein, trypsin, chymotrypsin, thrombin, urokinase, plasmin, tissue plasminogen activator, elastase, or Staphylococcus aureus V8 protease. TAP's specificity and size suggest that it may have therapeutic value as an anticoagulant.
 ...
PMID:Tick anticoagulant peptide (TAP) is a novel inhibitor of blood coagulation factor Xa. 233 10

Plasminogen activator inhibitor-2 (PAI-2) can regulate the formation of plasmin by inhibiting urokinase and tissue plasminogen activator. PAI-2 is induced in monocytes and endothelium by inflammatory mediators, and it is made in the placenta during pregnancy. PAI-2 is a member of the serine protease inhibitor gene family, and it is particularly similar to chicken ovalbumin. Like ovalbumin, PAI-2 is secreted without cleavage of a signal peptide. To determine the structure of the PAI-2 gene, two bacteriophage lambda human genomic DNA libraries were screened with PAI-2 cDNA probes. Characterization of three positive clones shows that the human PAI-2 gene spans 16.5 kilobases and has eight exons. The 5'-untranslated sequence of the PAI-2 mRNA is 77 base pairs in length as suggested by primer extension and S1 nuclease mapping. The eukaryotic consensus sequence TATAAAA is found 22 base pairs 5' of the proposed cap site. The PAI-2 gene is on chromosome 18q21-23 as determined by hybridization to flow-sorted chromosomes and by in situ hybridization. There appear to be two common PAI-2 alleles that differ by six nucleotides in exons 1, 4, and 8. The structure of the PAI-2 gene is quite different from that of PAI-1 although these two inhibitors have common target protease specificity. In contrast, the structure of the PAI-2 gene is very similar to that of the chicken ovalbumin gene. When protein sequences are aligned to obtain maximal identity, six of the seven intron positions in the PAI-2 gene are identical to those in the chicken ovalbumin gene. We conclude that PAI-2 is the closest mammalian homologue of avian ovalbumin.
 ...
PMID:Structure of the gene for human plasminogen activator inhibitor-2. The nearest mammalian homologue of chicken ovalbumin. 249 65

The interaction between type 1 plasminogen activator inhibitor (PAI-1), a serine protease inhibitor, and the three serine proteases generated during contact activation of plasma was studied using functional and immunologic approaches. Incubation of Factor XIIa, Factor XIa, and plasma kallikrein with either purified PAI-1 or platelet-derived PAI-1 resulted in the formation of sodium dodecyl sulfate-stable complexes as revealed by immunoblotting techniques. Functional assays indicated that Factor XIa and, to a lesser extent, Factor XIIa and plasma kallikrein neutralized the ability of purified PAI-1 to bind to immobilized tissue-type plasminogen activator (t-PA). Immunoblotting demonstrated that these enzymes also neutralized the ability of PAI-1 to form complexes with fluid-phase t-PA. Clot lysis assays employing purified proteins and 125I-fibrinogen were used to investigate the profibrinolytic effect of these contact activation enzymes. At enzyme concentrations that did not result in direct activation of plasminogen, only Factor XIa was capable of stimulating the lysis of clots supplemented with both t-PA and PAI-1. As a consequence of their interactions with PAI-1, the amidolytic activity of Factor XIIa, Factor XIa, and plasma kallikrein was neutralized by this inhibitor in a time-dependent and concentration-dependent manner. Minimum values estimated for the apparent second-order rate constant of inhibition were 1.6 x 10(4), 2.1 x 10(5), and 6.0 x 10(4) M-1 s-1 for Factor XIIa, Factor XIa, and plasma kallikrein, respectively. These data define new reactions between coagulation and fibrinolysis proteins and suggest that a major mechanism for stimulation of the intrinsic fibrinolytic pathway may involve neutralization of PAI-1 by Factor XIa.
 ...
PMID:Interaction of type 1 plasminogen activator inhibitor with the enzymes of the contact activation system. 278 18

Human purified urokinase-type plasminogen activator (u-PA) stimulates chemoattractant activity for human neutrophils using modified Boyden chambers. Checkerboard analysis performed by adding different concentrations of u-PA above and below the polycarbonate filters revealed maximum migration required a positive concentration gradient. These results suggest that uPA was in fact stimulating neutrophil chemotaxis. Incubation of u-PA with an anti-u-PA goat antibody completely abolished the chemotactic activity of u-PA while incubation with the serine protease inhibitor, diisopropyl fluorophosphate, did not reduce chemotactic activity. Purified human tissue-type plasminogen activator demonstrated no chemotactic activity for human neutrophils when tested at concentrations similar to u-PA. These results suggests that the expression of chemotactic activity of u-PA may serve to recruit circulating leukocytes to the inflammatory site.
 ...
PMID:Human urokinase-type plasminogen activator stimulates chemotaxis of human neutrophils. 311 59

Plasminogen activator inhibitor-2 (PAI-2) is a serine protease inhibitor that regulates plasmin generation by inhibiting urokinase and tissue plasminogen activator. The primary structure of PAI-2 suggests that it may be secreted without cleavage of a single peptide. To confirm this hypothesis we have studied the glycosylation and secretion of PAI-2 in human monocytic U-937 cells by metabolic labeling, immunoprecipitation, glycosidase digestion, and protein sequencing. PAI-2 is variably glycosylated on asparagine residues to yield intracellular intermediates with zero, one, two, or three high mannose-type oligosaccharide units. Secretion of the N-glycosylated species began by 1 h of chase and the secreted molecules contained both complex-type N-linked and O-linked oligosaccharides. Enzymatically deglycosylated PAI-2 had an electrophoretic mobility identical to that of the nonglycosylated precursor and also to that of PAI-2 synthesized in vitro in a rabbit reticulocyte lysate from synthetic mRNA derived from full length PAI-2 cDNA. The amino-terminal protein sequence of secreted PAI-2 began with the initiator methionine residue. These results indicate that PAI-2 is glycosylated and secreted efficiently without the cleavage of a signal peptide. PAI-2 shares this property with its nearest homologue in the serine protease inhibitor family, chicken ovalbumin, and appears to be the first well characterized example of this phenomenon among natural mammalian proteins.
 ...
PMID:Mammalian protein secretion without signal peptide removal. Biosynthesis of plasminogen activator inhibitor-2 in U-937 cells. 312 94

Recombinant tissue-type plasminogen activator (rt-PA) was administered intravenously to 93 patients with acute myocardial infarction and coronary thrombosis in doses of 30 to 150 mg over 1.5 to 6 hours. During this infusion plateau levels of rt-PA in plasma ranged between 0.4 and 2.2 micrograms/ml. Activation of the plasma fibrinolytic system and fibrinogen breakdown both in vivo and in vitro was observed with this therapy. In vitro fibrinogenolysis in plasma was more effectively prevented by collection of blood samples on aprotinin (200 kallikrein inhibitor units/ml blood), a conventional serine protease inhibitor, than on either of two monoclonal antibodies against t-PA (200 micrograms/ml plasma), or on D-phenylalanyl-prolyl-arginine-chloromethyl ketone (PPACK), a newly developed synthetic inhibitor of t-PA. Results of fibrinogen measurements during infusion of rt-PA were dependent on the method of assay. In a subgroup of 36 patients after completion of a thrombolytic infusion, fibrinogen decreased in vivo by 27% when measured as total coagulable protein and by 33% with a coagulation rate assay, but increased by 26% with an automated assay system. The extent of fibrinogenolysis was proportional to the plasma level of rt-PA but substantial intersubject variation was observed. Fibrinogenolysis in vivo was also associated with alpha 2-antiplasmin depletion and was more pronounced with a two-chain (G11021) than with a single-chain preparation (G11035) of rt-PA.
 ...
PMID:Laboratory monitoring of hemostasis during thrombolytic therapy with recombinant human tissue-type plasminogen activator. 313 34


1 2 3 4 5 6 7 Next >>