Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P00750 (PLA)
 16,800 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Human fibrosarcoma (HT-1080) cells, in contrast to normal fibroblasts, rapidly hydrolyze the glycoprotein, collagen, and elastin extracellular matrix (ECM) synthesized by cultured rat aortic smooth muscle cells. This degradation occurs at a rapid rate in the presence of serum, indicating that the cellular proteases responsible are relatively insensitive to serum proteinase inhibitors. Here it is shown that protease nexin I (PNI), a fibroblast-secreted inhibitor of urokinase, plasmin, and certain other serine proteinases, effectively inhibited the HT-1080 cell-mediated degradation of this ECM. PNI at 2.0 nM significantly inhibited matrix destruction for 1-2 days and at 0.2 microM caused a virtually complete inhibition that persisted for the entire 10-day period of observation. Inhibition of ECM destruction was accompanied by a transient arrest of HT-1080 cell proliferation that took place during the first 3 days after PNI addition. PNI did not inhibit the growth of normal fibroblasts and also did not inhibit the growth of HT-1080 cells that were seeded onto plastic dishes rather than onto ECM. Like many types of malignant cells, HT-1080 cells release large amounts of urokinase. Antibody against this plasminogen activator partially protected ECM from HT-1080 cell-mediated hydrolysis, indicating that it may have been a target of PNI. One potential physiological function of PNI could be to help maintain the integrity of connective tissue matrices, protection that malignant cells could overcome by secreting proteinases in excessive amounts.
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PMID:Inhibition of tumor-cell-mediated extracellular matrix destruction by a fibroblast proteinase inhibitor, protease nexin I. 351 69

The ability of B16-F10 mouse melanoma cells to cross an amnion basement membrane was determined in the presence of strong inhibitors of both serine and cysteine proteases. The concentrations of inhibitors were at orders of magnitude higher than their Ki values to serine and cysteine proteases implicated in metastasis, thus ensuring a complete inhibition for tumor secreted proteases such as cathepsin B-like proteases, plasminogen activators, and plasmin. Under these conditions of high serine and cysteine protease inhibitor concentrations, no significant decrease in B16-F10 melanoma cell invasion through the amnion was observed. Separate experiments showed that the inhibitors were neither toxic to the cells nor degraded. The results show that neither tumor cell secreted cathepsin B-like proteases nor plasminogen activator have a controlling role in basement membrane crossing in this metastatic model. A possible role for tumor cell membrane proteases in basement membrane invasion, in which the substrates of the protease bind to receptor sites near a membrane associated proteolytic activity, is not eliminated.
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PMID:Inhibition of proteolytic enzymes in the in vitro amnion model for basement membrane invasion. 352 1

We have purified and characterized the major N-benzoyl-L-arginine ethyl ester hydrolase from the venom of Heloderma horridum horridum. The enzyme belongs to the serine proteinase family, and its activity vs. peptide amide substrates and human high-molecular-weight kininogen suggests a similarity to the family of kallikreins. This interpretation is corroborated by its reactivity with the natural inhibitors soybean trypsin inhibitor and Kunitz-type bovine pancreatic trypsin inhibitor (aprotinin). Injection of the enzyme (2-16 micrograms/kg) into anesthetized rabbits leads to a rapid dose-dependent transient decrease of the arterial blood pressure. Like glandular kallikrein it specifically converts single-chain tissue type plasminogen activator into its double chain form. In contrast to other kallikrein-like enzymes from snake venoms it shows no thrombin-like or plasminogen activator activity. The enzyme is a single-chain glycoprotein (Mr 63,000). The N-terminal sequence revealed significant homology to pig pancreatic kallikrein and to kallikrein like enzymes from Crotalus atrox and Crotalus adamanteus venom. This enzyme, which we name Helodermatine, is the first purified from Sauria with kallikrein-like properties.
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PMID:Helodermatine, a kallikrein-like, hypotensive enzyme from the venom of Heloderma horridum horridum (Mexican beaded lizard). 353 91

Lung microvascular injury induced in sheep by intravenous infusion of Escherichia coli endotoxin, oleic acid, or air emboli caused the appearance in lung lymph of high levels of a protease with trypsin-like activity. The enzyme was isolated as an apparently homogeneous protein from pooled samples of active lung lymph, after an almost 9000-fold purification by affinity chromatography on columns of Reactive Blue 2-agarose, aprotinin-agarose, and p-aminobenzamidine-agarose, and chromatography on a column of Sephadex G-100. A molecular weight of about 70,000 to 75,000 was determined from mobility in polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. The pH optimum was between 7.3 and 7.6. The isolated enzyme was quite labile, rapidly losing activity at both 37 and 25 degrees C. Addition of albumin to enzyme solutions protected against inactivation. Inhibition by diisopropylfluorophosphate and phenylmethanesulfonyl fluoride indicated that the enzyme belongs to the class of serine proteases. The enzyme cleaved peptide bonds on the carboxyl side of arginine residues and showed a relatively high affinity toward peptides containing several basic amino acid residues. Bonds involving the carboxyl group of lysine were cleaved at a much slower rate. The enzyme showed no plasminogen activator activity and its substrate specificity was quite different from that of several proteases of the clotting cascade. Its appearance in lymph was not influenced by lymph clotting and the isolated enzyme was not capable of correcting the clotting defect of plasmas deficient in factors XII, XI, IX, VII, and X.
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PMID:Isolation and properties of a capillary injury-related protease from lung lymph. 355 41

A human liver cDNA library was screened by colony hybridization with two mixtures of synthetic oligodeoxyribonucleotides as probes. These oligonucleotides encoded regions of beta-factor XIIa as predicted from the amino acid sequence. Four positive clones were isolated that contained DNA coding for most of factor XII mRNA. DNA sequence analysis of these overlapping clones showed that they contained DNA coding for part of an amino-terminal extension, the complete amino acid sequence of plasma factor XII, a TGA stop codon, a 3' untranslated region of 150 nucleotides, and a poly(A)+ tail. The cDNA sequence predicts that plasma factor XII consists of 596 amino acid residues. Within the predicted amino acid sequence of factor XII, we have identified three peptide bonds that are cleaved by kallikrein during the formation of beta-factor XIIa. Comparison of the structure of factor XII with other proteins revealed extensive sequence identity with regions of tissue-type plasminogen activator (the epidermal growth factor-like region and the kringle region) and fibronectin (type I and type II homologies). As the type II region of fibronectin contains a collagen-binding site, the homologous region in factor XII may be responsible for the binding of factor XII to collagen. The carboxyl-terminal region of factor XII shares considerable amino acid sequence homology with other serine proteases including trypsin and many clotting factors. A preliminary structural model of beta-factor XIIa is proposed based on the known high resolution x-ray diffraction structures of trypsin, chymotrypsin, and elastase.
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PMID:Characterization of human blood coagulation factor XII cDNA. Prediction of the primary structure of factor XII and the tertiary structure of beta-factor XIIa. 387 53

Production of plasminogen activator (PA) by granulosa cells (GC) and its stimulation by gonadotropins led to the suggestion that PA is involved in ovulation. However, whereas only LH may be regarded as the ovulation-inducing hormone in the rat, FSH was found to be much more potent than LH in enhancing PA production by GC. Assuming that the entire follicular wall, rather than isolated GC, is involved in follicular rupture, we have examined activity of PA in intact follicles. LH (NIH-LH-S23) was 5-fold more potent than FSH (NIH-FSH-S14), and purified ovine LH and FSH were equally potent in enhancing follicular PA activity. Furthermore, injection into the ovarian bursa of proestrous rats of epsilon-amino-caproic acid and benzamidine (0.05-0.25 mmol), inhibitors of serine proteases, including PA and plasmin, resulted in a dose-dependent inhibition of ovulation without causing changes discernible by histological examinations of the ovaries. Whereas steroids did not change basal follicular PA production in culture, addition of estradiol-17 beta [(E2) 1 microgram/ml] but not progesterone or testosterone, further enhanced LH-stimulated PA. Aminoglutethimide phosphate (10(-3) M) and 17 beta-formamidoandrost-4-en-3-one inhibited LH-induced increase in follicular PA and this inhibition was reversed by addition of E2. Intrabursal injection of indomethacin, an inhibitor of cyclooxygenase, and of nordihydroguaiaretic acid, an inhibitor of lipoxygenase pathway of arachidonic acid metabolism at doses which effectively blocked ovulation (0.3 mg/bursa) had no effect on PA content of the follicles. Likewise, indomethacin (10 microM) and nordihydroguaiaretic acid (100 microM) did not affect LH-stimulated PA in vitro. In conclusion, LH, the physiological trigger of ovulation is, at least, as potent as FSH in stimulating follicular PA activity. The role of serine proteases, most probably of PA and plasmin, in ovulation is further corroborated by a pharmacological approach. LH stimulation of follicular PA appears to be enhanced by E2 but is not mediated by arachidonic acid metabolites.
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PMID:Follicular plasminogen activator: involvement in ovulation. 391 2

Twelve amino acid sequences of kringle-forming polypeptides were compiled from the known sequences of urokinase A-chain (human), a tissue-type plasminogen activator (human), prothrombin (human and bovine), and plasminogen (human). Their sequence homologies with maximum match were examined by a computer program. A homology alignment and graphic matrix analyses did show that they had a great degree of homology. All the cysteine residues responsible for the kringle structures of urokinase and the tissue-type plasminogen activator were confidently preserved as well as other proteins. A phylogenetic tree was then reconstructed, and the A- and S-chain of bovine and human prothrombins were accounted for the measurement of the evolutionary time span. It was found that urokinase had a larger time span, as much as 60 million years (MY), than the tissue-type plasminogen activator. A common ancestral element of the kringle-related serine proteases was placed at around 500 MY ago, as old as the diversion of the alpha- and beta-chains of hemoglobin. Thus, the kringle-families have undergone a substantial evolutionary divergence. Moreover, they can be subgrouped into three subfamilies: plasminogen activators, plasminogen, and prothrombin A-chains, the last being the most distantly diverged prothrombin S-chains.
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PMID:Homology of kringle structures in urokinase and tissue-type plasminogen activator: the phylogeny with the related serine proteases. 393 78

A plasminogen activator secreted from human kidney cells was highly purified by affinity chromatography on an anti-urokinase IgG-Sepharose column. The purified plasminogen activator was inactive and had a single-chain structure and a Mr of 50,000. It not only did not incorporate diisopropyl fluorophosphate, which reacts with active site serine residue in urokinase, but also did not bind to p-aminobenzamidine-immobilized CH-Sepharose, to which urokinase bind via its side-chain binding pocket present in active center. The plasminogen activator was converted to the active two-chain form with the same Mr by catalytic amounts of plasmin. Its potential enzymatic activity was quenched completely by anti-urokinase IgG, but not by anti-tissue plasminogen activator Ig. These results indicate that the plasminogen activator is an inactive proenzyme form of human urokinase. Therefore, the plasminogen activator was termed single-chain pro-urokinase. The cleavage of single-chain pro-urokinase by plasmin induced conformational change which followed the generation of reactive serine residue at active site, the increase enzyme activity and the reduction of its high affinity for fibrin. These findings suggest that conformational change occurs in both regions responsible for enzyme activity and affinity for fibrin upon activation of single-chain pro-urokinase.
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PMID:Proteolytic cleavage of single-chain pro-urokinase induces conformational change which follows activation of the zymogen and reduction of its high affinity for fibrin. 393 Apr 94

Previously, we showed that the clotting factor thrombin binds to bovine corneal endothelial cells forming a covalent complex with a protein released by these cells into the culture media. We report that the plasminogen activator, urokinase, an enzyme involved in dissolution of blood clots, binds specifically to bovine corneal endothelial cells. [125I]-urokinase is rapidly bound by corneal endothelial cells. The serine active site of urokinase is required for binding since [125I]-urokinase inactivated with diisoprophylfluorophosphate does not bind to the cells. Pre-incubation of corneal cells with unlabeled urokinase for 20 hr results in increased release of binding sites for [125I]-urokinase into the culture media and at least a 3.5-fold increase in binding by the cells. [125I]-urokinase forms a 73 300 dalton sodium dodecyl sulfate complex with a corneal endothelial cell protein. Although thrombin competes with urokinase for binding to corneal endothelial cells, urokinase has at least a 10-fold higher affinity for binding to the cells. Furthermore, these cells make a plasminogen activator identical in molecular weight to urokinase. Thus, under physiological conditions, urokinase rather than thrombin binds to corneal endothelial cells. Binding may serve to regulate endogenous urokinase activity in the anterior chamber of the eye by limiting its extracellular proteolytic activity.
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PMID:Urokinase binding to bovine corneal endothelial cells. 406 54

A series of human cell lines has been examined for fibrinolysis in culture. The sera that are activating for fibrinolysis by human cells are mouse, monkey, human, horse, and bovine. Individual human sera show considerable variation in the ability to activate fibrinolysis. In common with other neoplastic or transformed mammalian and avian cell cultures, human cell lines of neoplastic origin produce substantial amounts of plasminogen activator. Several cultures of nonmalignant origin also produce plasminogen activator, whereas cultures obtained from trypsinized human embryos, or from human embryonic skin do not. The human melanoma plasminogen activators are of two kinds: a major component with a mol wt of 50,000, and a minor species with a mol wt of approximately 60,000. Both are DFP sensitive, serine proteases.
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PMID:Properties of plasminogen activators formed by neoplastic human cell cultures. 420 24


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