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)

Pulmonary hypertension may be associated with multiple thrombi in the pulmonary arteries or with diffuse microembolization from a cryptic source. A 27-year-old man without any of the recognized clinical risk factors for venous thrombo-embolic disease presented with repeated attacks of chest pain and dyspnoea. Haemodynamic studies were compatible with the diagnosis of primary pulmonary hypertension. Despite intensive study there was no evidence of peripheral venous thrombosis. A survey of the plasma fibrinolytic profile showed unequivocal evidence of low spontaneous plasma fibrinolytic activity. The plasminogen activator activity of the venous wall was also markedly reduced. From these findings it would seem that a defective fibrinolytic defence mechanism may be an important predisposing factor in the pathogenesis of 'primary' pulmonary hypertension.
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PMID:A possible causal relationship between defective fibrinolysis and pulmonary hypertension. 42 66

Apart from tissue-type plasminogen activator (t-PA) and urokinase-type plasminogen activator (u-PA), a third PA appears to occur in human plasma. Its activity is initiated when appropriate triggers of the contact system are added, and the activation depends on the presence of factor XII and prekallikrein in plasma. The activity of this, so-called, contact-system dependent PA accounts for 30% of the PA activity in the dextran sulphate euglobulin fraction of plasma and was shown not to be an intrinsic property of one of the contact-system components, nor could it be inhibited by inhibitory antibodies against t-PA or u-PA. We have succeeded in identifying this third PA in dextran sulphate euglobulin fractions of human plasma. Its smallest unit (SDS-PAGE) is an inactive 110 kDa single-chain polypeptide which upon activation of the contact system is converted to a cleaved, disulphide-bridged molecule with PA activity. The native form, presumably, is an oligomer, since the apparent Mr on gel-chromatography is 600,000. The IEP is 4.8, much lower than that of t-PA and u-PA. Although the active 110 kDa polypeptide cannot be inhibited by anti-u-PA, it yet comprises a 37 kDa piece with some u-PA related antigenic determinants. However, these determinants are in a latent or cryptic form, only detectable after denaturation by SDS. The 110 kDa polypeptide is evidently not a dimer of 55 kDa u-PA or a complex of u-PA with an inhibitor.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The contact-system dependent plasminogen activator from human plasma: identification and characterization. 212 68

Plasminogen activator inhibitor 1 (PAI-1) is the primary inhibitor of tissue-type plasminogen activator and thus performs an essential role in the regulation of the fibrinolytic process. It is a member of a large family of serine protease inhibitors (serpins). We determined the structure of the PAI-1 gene in order to more completely investigate the relationship of PAI-1 to other serpins and, at the same time, to begin to delineate structure-function relations in PAI-1 itself. A human genomic cosmid DNA library was screened and found to contain two independent clones, each harboring the entire PAI-1 gene. Restriction site mapping, electron microscopic inspection of heteroduplexes, and nucleotide sequence analysis all demonstrate that the PAI-1 gene is approximately 12.2 kilobase pairs in length and consists of nine exons and eight introns. All intron-exon boundaries are in accord with the "GT-AG" rule, including a cryptic acceptor splice site found in intron 7. The intron-exon pattern of the PAI-1 gene is distinct from that of most other serpins except that intron 3 of PAI-1 occupies an identical position as intron E of ovalbumin. Comparison of our data with the proposed subdomain structure of serpins suggests that seven of the eight introns may occupy a nonrandom position in the gene. These introns either delineate boundaries of individual structural subdomains or are located in random coil regions of the protein. Transcription of the PAI-1 gene in cultured vascular endothelial cells results in two distinct mRNA species. Our data suggest that these two transcripts arise by alternative polyadenylation.
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PMID:Structure of the human plasminogen activator inhibitor 1 gene: nonrandom distribution of introns. 282 Apr 74

Human foreskin cells possess sites on their surfaces that specifically bind both active and diisopropylphosphofluoridate-inactivated 2 chain 54 K Da [125I]-urokinase, but do not bind the 54 K Da single chain form of urokinase. 125I-urokinase bound to these sites is not internalized and is very slow to dissociate. There are about 40,000 available binding sites per cell. Brief incubation with pH 2.5 buffer at 5 degrees C unmasks another two to six fold more sites and also extracts plasminogen activator that, based on its accessibility to trypsin, appears to be at the cell surface. This suggests that the cryptic urokinase binding sites could be sites occupied with endogenous plasminogen activator.
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PMID:Cryptic urokinase binding sites on human foreskin fibroblasts. 300 45

A two-site immunoradiometric assay for tissue plasminogen activator (tPA) antigen has been developed using immunoaffinity purified antibody. Various treatments enhanced the detection of tPA antigen in the plasma samples. Maximum detection was obtained by acidification of plasma to pH 4.8 to 6.5 or addition of 0.5 mol/L of L-lysine or L-arginine. Acidification or addition of lysine to plasma is also required for maximum immunoadsorption of plasma tPA antigen on anti-tPA-Ig-sepharose. These results indicate that plasma tPA antigen is partially cryptic to antibody in untreated plasma. The plasma tPA antigen isolated by immunoadsorption of either untreated plasma or acidified plasma on anti-tPA-Ig-sepharose consists mainly of a 100-kd plasminogen activator species as determined by fibrin-agar zymography. The 100-kd activity is possibly a tPA:inhibitor complex. A standardized sample preparation method was conveniently adopted by mixing 3 vol of plasma and 1 vol of 2 mol/L of L-lysine for the assay. Reconstitution and recovery studies showed that the method is specific and permits full detection of both free tPA and tPA:inhibitor complex. The validity of the assay is further supported by the finding that the spontaneous plasma fibrinolysis previously demonstrated to be dependent on plasma tPA antigen is correlated with tPA antigen content. Using the standardized assay, we found that tPA antigen concentrations in 16 blood bank plasmas are equivalent to 3.7 to 20 ng of 60 kd tPA/mL. In all the plasma tested, more than half of the antigen is undetected unless the plasma is treated as described above.
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PMID:Immunoradiometric quantitation of tissue plasminogen activator-related antigen in human plasma: crypticity phenomenon and relationship to plasma fibrinolysis. 310 18

Line 10 guinea pig carcinoma cells cultured in serum-free medium for 4 hr elaborate plasminogen activator (PA) activity that remained in the supernatant after ultracentrifugation (100,000 X g, 90 min). PA activity in line 10 conditioned medium occurred in both active and cryptic forms. The vast majority of active PA adsorbed to lysine-Sepharose and could be eluted at low pH as several activities that electrophoresed in the Mr 50,000 to 80,000 range on nonreduced sodium dodecyl sulfate-polyacrylamide gel electrophoresis. A small amount of active PA, running in the Mr 50,000 to 60,000 region, and cryptic PA did not adhere to lysine-Sepharose. Treatment of lysine-Sepharose-nonadherent fractions with catalytic amounts of plasmin or trypsin induced substantial new PA activity that adsorbed to lysine-Sepharose, bound [3H]diisopropylfluorophosphate, and that electrophoresed as several bands of activity with molecular weights from 50,000 to greater than 100,000 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Of additional interest, the amount of active PA measured in conditioned medium was substantially increased when certain protease inhibitors, tranexamic acid, epsilon-aminocaproic acid, or Trasylol, were included during culture.
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PMID:Cryptic and active plasminogen activators secreted by line 10 tumor cells in culture. 668 8

Yersinia pestis, the etiologic agent of plague, carries three prototypic plasmids with sizes of 110 kb (pFra, pTox), 70 kb (pLcr, pVW, pCad), and 9.5 kb (pPla, pPst). Studies suggest that geographic isolates of Y. pestis may be differentiated by plasmid profiles. Yersinia pestis isolated from the western United States harbor an additional plasmid, estimated to be approximately 19 kb in size. This cryptic plasmid was characterized by restriction endonuclease digestion, amplification and sequencing of the plasminogen activator gene segment, Southern blotting, and visualized by electron microscopy. Results revealed that this cryptic plasmid is a supercoiled DNA plasmid, 18.85+/-0.59 (mean+/-SD) kb in length, and is a dimer of the 9.5-kb plasmid. The genetic reason for the appearance of this form of the 9.5-kb plasmid in Y. pestis from Arizona, California, Colorado, New Mexico, and Texas is under study.
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PMID:A cryptic 19-kilobase plasmid associated with U.S. isolates of Yersinia pestis: a dimer of the 9.5-kilobase plasmid. 984 May 81

The low density lipoprotein receptor-related protein (LRP), a multi-functional endocytic receptor, mediates the cellular internalization of tissue-type (t-PA) and urokinase-type (u-PA) plasminogen activator and their complexes with plasminogen activator inhibitor type 1 (PAI-1). LRP preferentially binds the complexed forms, exemplified by equilibrium dissociation constants (KD) that are at least an order of magnitude lower than those of the free components. To understand the molecular interactions, underlying the preference of the receptor for complexes rather than for the free components, we have performed a detailed analysis of the affinity and kinetics of the binding of PAI-1 and t-PA:PAI-1 complexes to the receptor, using surface plasmon resonance. To assess the involvement of the heparin-binding domain of PAI-1 for the interaction with LRP, we determined the equilibrium dissociation constants for the binding to LRP of a panel of PAI-1 mutants with single- and multiple amino-acid substitutions of the basic residues that constitute the heparin binding site of PAI-1 (K65, K69, R76, K80 and K88). The binding of these PAI-1 mutants was partially reduced with a 2 to 4 fold increase in KD values for single (K80, K88) and combined (K80, 88) substitution mutant proteins respectively. LRP binding of complexes, composed of t-PA with either wild type PAI-1 or any one of the single PAI-1 mutants indicated a major role of lysine 69 (K69) for the binding of t-PA:PAI-1 complexes to LRP (KD values of 6.1, 3.7. 75.4, 5.4, 12.5 and 8.1 nM for wild type, K65A, K69A, R76A, K80A and K88A complexes, respectively). Since the KD for the binding of free t-PA to LRP is 158 nM, we conclude that the PAI-1 moiety harbors the major determinant for t-PA:PAI-1 complex binding to LRP. The in vitro binding studies were extended by binding and clearance studies with COS-1 cells. Degradation of both 125I-t-PA:PAI-1 K69A and 125I-t-PA:PAI-1 K69A K80A K88A complexes after 2 h of incubation was reduced compared to the degradation of 125I-t-PA:PAI-1 complexes. We conclude that PAI-1 contains a cryptic binding site (lysine 69) for LRP, that is specifically expressed upon t-PA:PAI-1 complex formation.
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PMID:Plasminogen activator inhibitor 1 contains a cryptic high affinity receptor binding site that is exposed upon complex formation with tissue-type plasminogen activator. 984 78

Neuroserpin, a recently identified inhibitor of tissue-type plasminogen activator (tPA), is primarily localized to neurons within the central nervous system, where it is thought to regulate tPA activity. In the present study neuroserpin expression and its potential therapeutic benefits were examined in a rat model of stroke. Neuroserpin expression increased in neurons surrounding the ischemic core (ischemic penumbra) within 6 hours of occlusion of the middle cerebral artery and remained elevated during the first week after the ischemic insult. Injection of neuroserpin directly into the brain immediately after infarct reduced stroke volume by 64% at 72 hours compared with control animals. In untreated animals both tPA and urokinase-type plasminogen activator (uPA) activity was significantly increased within the region of infarct by 6 hours after reperfusion. Activity of tPA then decreased to control levels by 72 hours, whereas uPA activity continued to rise and was dramatically increased by 72 hours. Both tPA and uPA activity were significantly reduced in neuroserpin-treated animals. Immunohistochemical staining of basement membrane laminin with a monoclonal antibody directed toward a cryptic epitope suggested that proteolysis of the basement membrane occurred as early as 10 minutes after reperfusion and that intracerebral administration of neuroserpin significantly reduced this proteolysis. Neuroserpin also decreased apoptotic cell counts in the ischemic penumbra by more than 50%. Thus, neuroserpin may be a naturally occurring neuroprotective proteinase inhibitor, whose therapeutic administration decreases stroke volume most likely by inhibiting proteinase activity and subsequent apoptosis associated with focal cerebral ischemia/reperfusion. (Blood. 2000;96:569-576)
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PMID:Neuroserpin reduces cerebral infarct volume and protects neurons from ischemia-induced apoptosis. 1088 20

Tissue-type plasminogen activator (t-PA) is a valuable thrombolytic agent because of its high affinity to fibrin. When produced in mammalian cell lines, it is glycosylated, a modification that is believed to promote its rapid clearance from the circulation. Bacteria such as Escherichia coli have been tested as alternative expression systems but were not able to express the cDNA of t-PA effectively. The coding sequence for t-PA revealed a significant proportion of AGA and AGG codons, which are rarely used in the coding sequences of E. coli. The argU and argW gene products of E. coli proved to be minor tRNA(arg) species, respectively decoding the very rare triplets AGA/AGG and AGG for arginine. Analysis of genomic fragments from E. coli for both tRNA(arg) genes revealed the presence of defective, cryptic prophages integrated within the impaired tRNA genes. Cloning and supplementation of the limiting tRNA genes argU and argW on helper plasmids improved the translation of the rare AGA and AGG codons. This augmentation improved bacterial growth and enhanced t-PA production in the form of inactive inclusion bodies. This dependence on augmentation of tRNA(arg4) or tRNA(arg5) for improved cell growth and expression was also observed for other genes with a high content of these rare arginine codons. Construction and production of nonglycosylated t-PA in inclusion bodies in E. coli along with improvement of the subsequent renaturation and purification procedures resulted in material comparable to that derived from CHO cells. Deletion of domain-encoding segments yielded various "muteins" of t-PA (e.g., reteplase [rPA]) that could be produced in and activated from the purified inclusion bodies analogously. Furthermore, it was shown that rPA has an extended half-life in the circulation because of its lack of glycosylation and impaired receptor binding capability. rPA was successfully used in various clinical studies. It is a new-generation thrombolytic agent with a longer half-life and can thus be administered more conveniently as a double bolus.
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PMID:The production of improved tissue-type plasminogen activator in Escherichia coli. 1154 55


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