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Query: UNIPROT:P00750 (PLA)
 16,800 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Highly metastatic cell lines have been isolated from lung foci formed by the intravenous injection of large numbers (5 X 10(6)) of cells of a poorly metastatic rat mammary adenocarcinoma (DMBA-8). The metastatic variant lines were phenotypically different and, unlike the parent line, produced high levels of plasminogen activator (PA) separable into three major bands (MW 30,000, 48,000 and 83,000) on SDS-PAGE. It is suggested that PA may play a role in the enhanced metastatic ability of these cells. Using parallel DMBA-8 clones the rate of generation of the metastatic variant cells was estimated, by fluctuation analysis, to be approximately 1.85 X 10(-6) per cell generation.
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PMID:Enhanced plasminogen activator production by highly metastatic variant cell lines of a rat mammary adenocarcinoma. 373 65

Urine samples from 10 species of mammals were analyzed by SDS-PAGE followed by zymography for the presence of both plasminogen activators and plasminogen activator binding proteins. In contrast to results obtained with urine from humans (Homo sapiens), and to a lesser extent urine from baboons (Papio cynocephalous), urine from gorillas (Gorilla gorilla) and orangutans (Pongo pygmaeus) did not exhibit either very high molecular weight plasminogen activators or the presence of plasminogen activator binding proteins. Low levels of very high molecular weight plasminogen activators could be detected in concentrates of urine samples from rabbits (Oryctolagus cuniculus), dogs (Canis familiaris) and sheep (Ovis aries). Very high molecular weight plasminogen activators could be detected in unconcentrated guinea-pig (Cavia porcella) urine, concentrated urine samples from rats (Rattus norvegicus), but not in concentrated samples of urine from mice (Mus musculus). These results indicate that considerable variation between species exists at the level of the plasminogen activators present in urine, a finding that may relate to whether plasminogen activator binding proteins are also present in this fluid.
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PMID:Species differences in the detection of high molecular weight urinary plasminogen activators. 374 21

We have isolated a cDNA clone corresponding to a substantial portion of the human tissue-type plasminogen activator (t-PA) protein. It encodes almost all of the protein B chain and part of the 3' untranslated region. We have used this clone to screen bacteriophage lambda and cosmid libraries of human genomic DNA. Several related genomic clones were isolated. One of these, a cosmid clone, carried approx. 40 kb of human DNA. Mapping experiments indicate that the region containing the protein-coding exons is approx. 20 kb in length. The cosmid, containing the t-PA gene and the aminoglycosyl-3'-phosphotransferase dominant-selection marker, was introduced into mouse L cells. Approximately half of the transformants were shown to produce human t-PA. We demonstrated that the fibrinolytic t-PA activity could be specifically quenched by anti-t-PA antibody and that the recombinant t-PA was of similar size (by SDS-polyacrylamide gel electrophoresis) to the t-PA produced by the human Bowes melanoma cell line. Our results suggest that the cosmid clone carries the whole t-PA coding region together with the regulatory elements necessary for its expression.
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PMID:Isolation of a human tissue-type plasminogen-activator genomic DNA clone and its expression in mouse L cells. 383 98

A plasminogen activator inhibitor (PA-I) which inhibits primarily plasminogen activator of the urokinase type (u-PA) was isolated from the cytosol of human peripheral leukocytes. The inhibitor was isolated using ion exchange chromatography, gel filtration and FPLC. This inhibitor has an apparent molecular weight of 45 kDa, determined by SDS-PAGE, and a pI of 5.5-5.7. The inhibitor is a fast reacting inhibitor, is thermally unstable and is inactivated outside the pH range 7-9. Treatment of cytosol to pH 9 for 30 min at 37 degrees C resulted in a large increase in inhibitory activity. Antibodies against human placental UK-I completely quenched the inhibitory activity of human leucocyte UK-I.
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PMID:Human leucocyte urokinase inhibitor--purification, characterization and comparative studies against different plasminogen activators. 387 18

We immunocytochemically stained rat pituitary glands using antibodies against plasminogen activators of the tissue type (t-PA) and the urokinase type (u-PA). A large population of endocrine cells in the anterior lobe of the gland displayed intense cytoplasmic immunoreactivity with anti-t-PA. In some areas of the intermediate lobe we found a weak staining, and we observed weakly staining granular structures in the posterior lobe. Controls included absorption of the antibodies with highly purified t-PA. In addition, SDS PAGE followed by immunoblotting of pituitary gland extracts revealed only one band with an electrophoretic mobility similar to that of t-PA when stained with anti-t-PA IgG. No u-PA immunoreactivity was detected in the rat pituitary gland. Sequential staining experiments using antibodies against growth hormone and t-PA demonstrated that the t-PA-immunoreactive cells constitute a large subpopulation of the growth hormone-containing cells. These findings represent the first direct evidence for the presence of t-PA in cell types other than endothelial cells in the intact normal organism. In this article we discuss the implications of the results for a possible role of t-PA in the posttranslational processing of prohormones.
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PMID:Immunocytochemical demonstration of tissue-type plasminogen activator in endocrine cells of the rat pituitary gland. 389 62

Alveolar macrophages are intimately involved with fibrin during the course of acute and chronic inflammatory processes in the lung. In this study, the capability of macrophages to impede fibrinolysis was investigated. Human alveolar macrophages obtained by lavage from normal volunteers released a fibrinolytic inhibitor during the first 24 h of in vitro culture but only inconsistently and in some cases (7 of 15) not at all. Lysates of freshly lavaged cells had no activity. Endotoxin, 5 to 100 ng/ml, consistently induced intracellular accumulation and extracellular release of a fibrinolytic inhibitor by cultured macrophages. Induction required protein synthesis. The intracellular and secreted forms of the inhibitor were true plasminogen activator (PA) inhibitors, as judged by their ability to block urokinase-mediated conversion of 125I-plasminogen. On average, 10(7) endotoxin-stimulated macrophages secreted sufficient PA inhibitor during a 24-h culture in vitro to neutralize 2 picomoles urokinase (16 international units). Analysis of the interaction of the human macrophage PA inhibitor with 125I-urokinase (apparent size, 33 kilodaltons) by SDS-gel electrophoresis showed that the enzyme and inhibitor mostly dissociated in SDS, but a stable complex occurred at 60 to 65 kilodaltons and a broad band of enzyme or enzyme-inhibitor complexes between 33 and 40 kilodaltons. Either heat treatment of the inhibitor or active site inhibition of urokinase with p-nitrophenylguanidinobenzoate blocked both types of interaction. The pattern of interaction was virtually indistinguishable from that of a partially purified human placental urokinase inhibitor but different from that of serum protease inhibitors.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:A fibrinolytic inhibitor of human alveolar macrophages. Induction with endotoxin. 389 43

The plasminogen activator exists in the human placenta (PPA) as a reversible complex with its inhibitor (UKI). Plasminogen activating activity appeared resulting from the separation of UKI from PPA-UKI complex through UK-Sepharose or UK-Affi Gel 10 affinity chromatography. This crude PPA was purified through gel filtration on Sephadex G-150 and DEAE-Sephacel column chromatography. The purified PPA was obtained at a rate of 25 micrograms from one placenta, the specific PA activity of which was 21, 071 IU/mg-protein. The molecular weight of PPA was estimated at about 65,000 (unreduced) by SDS-polyacrylamide gel electrophoresis. PPA did not react to the anti-UK serum and UK did not react to the anti-PPA serum. It is revealed that PPA has a smaller influence on fibrinogenolysis than UK does. PPA is a new plasminogen activator in the human placenta, which has different properties from UK biologically and immunologically. It is speculated that in the near future PPA will be one of the tissue activators in thrombolytic therapy for thrombotic diseases including toxemia. We note that the measurement of the plasma PPA level is useful as one of the marker proteins of placental function and malignant tumors.
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PMID:Purification and characterization of placental plasminogen activator (PPA). 392 41

Pure cultures of bovine endothelial cells (EC) produce and secrete large amounts of plasminogen activators (PA). Cocultivation of EC with vascular smooth muscle cells (SMC) resulted in a significant decrease of PA activities secreted by the EC, whereas the cellular PA activities remained unaffected. Secreted PA activities were absent in the growth medium as long as the SMC to EC ratio was 2:1 or higher. The PA inhibitory activity of the SMC was rapid and cell-to-cell contact was not necessary. The PA inhibitory activity was present in homogenates of SMC as well as in the medium conditioned by them but not in the extracellular matrix elaborated by these cells. Serum free medium conditioned by SMC neutralized both tissue type (t-PA) and urokinase like (u-PA) plasminogen activators. Gel electrophoretic analysis of SMC conditioned medium followed by reverse fibrin autography demonstrated PA inhibitory activities in the molecular weight (Mr) range of 50,000 to 52,000 similar to those present in media conditioned by bovine endothelial cells or fibroblasts. Regular fibrin zymography of SMC conditioned medium incubated with u-PA or t-PA revealed the presence of a component with a calculated approximate Mr of 45,000 to 50,000 which formed SDS resistant complexes with both types of PA. These data demonstrate that vascular SMC produce and secrete (a) inhibitor(s) of PAs which may influence the fibrinolytic potential of EC.
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PMID:Vascular smooth muscle cells inhibit the plasminogen activators secreted by endothelial cells. 392 3

A plasminogen activator has been partially purified from benign serous cystadenomas by a combination of Sephadex G-200 gel filtration, CM-Sephadex ion exchange, Concanavalin A-Sepharose and arginine-Sepharose affinity chromatographies. Its apparent size was very large and could not penetrate Sepharose 6B or 5% SDS polyacrylamide gel. It hydrolyzed plasminogen in a manner similar to that of urokinase in terms of their apparent Michaelis constants, although a one-minute lag period had to be allowed for this activation before the hydrolysis of plasminogen. It was very sensitive to reducing agent such that 5 mM dithiothreitol could completely destroy its activity. The activator crossreacted with anti-uterine plasminogen activator IgG, but did not react with anti-urokinase at all. It also bound fibrin well. In the absence of plasminogen, the activator was devoid of amidolytic activity towards S-2251, S-2302 and S-2288 but had a small but measurable activity against S-2444.
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PMID:A plasminogen activator from benign ovarian cystadenoma: partial purification and characterization. 396 43

Human urine was found to contain multiple species of urokinase (UK)-like plasminogen activator (PA) activity when subjected to concentration and/or dialysis and analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and zymography. Untreated, freshly voided urine contained only Mr = 52,000 and 35,000 UK while dialyzed or undialyzed urine concentrates contained additional PA activity at Mr = 80,000 and 95,000. SDS-PAGE of incubation mixtures of radioiodinated UK (Mr = 52,000 or 35,000) and urine concentrates revealed the presence of radiolabeled complexes with Mrs of 80,000 and 95,000. The bond(s) involved in complex formation was also relatively resistant to heat and reduction. Treatment of radioiodinated UK with the serine proteinase inhibitor, p-nitrophenyl guanidinobenzoate, prior to incubation with dialyzed, concentrated urine prevented formation of the complexes. In addition, the enzymatic activity of the Mr = 80,000 and 95,000 species was unaffected by diisopropyl fluorophosphate. These results indicate that UK forms SDS-stable complexes with a urinary component that has a Mr of approximately 40,000. The results further suggest that these complexes express PA activity when analyzed by SDS-PAGE and zymography.
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PMID:Formation of stable complexes between urokinase and a human urinary component. 403 74


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