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)

Vascular injury induced by angioplasty is often followed by smooth muscle cell (SMC) proliferation, migration, and accumulation of extracellular matrix. Since plasminogen activators and their receptors may be important both in cell migration and the clearance of plasminogen activators, we studied the binding, internalization, and degradation of radiolabeled tissue-type plasminogen activator (t-PA) by explant cultures of human vascular SMC. Binding of t-PA to SMC at 4 degrees C was rapid, specific, saturable, and inhibitable by antibodies to plasminogen activator inhibitor type 1 (PAI-1). At 37 degrees C, labeled t-PA was internalized and degraded by SMC but not by human umbilical vein endothelial cells. Internalization and degradation was mediated by the low density lipoprotein receptor related protein/alpha 2-macroglobulin receptor (LRP) in that these processes were inhibited by an anti-LRP antibody, recombinant LRP-associated protein, urokinase-type plasminogen activator-PAI-1 complexes, and lactoferrin. The portion of t-PA most important for internalization after complexing with PAI-1 is likely to be in the finger and/or epidermal growth factor domains or in the carbohydrate at amino acid 117, in that the internalization of preformed t-PA.PAI-1 complexes or complexes formed on the cell surface was inhibited by an excess of active site-blocked wild type t-PA, but not by an active site blocked t-PA variant missing these domains. These studies are consistent with a model in which t-PA binds initially to SMC-associated PAI-1 with subsequent t-PA.PAI-1 internalization via LRP. SMC may play an important role in clearing t-PA-PAI-1 complexes from within the vessel wall.
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PMID:Determinants of binding and internalization of tissue-type plasminogen activator by human vascular smooth muscle and endothelial cells. 768 59

The present study was undertaken in order to determine the recognition site for tissue-type plasminogen activator-plasminogen activator inhibitor type 1 [t-PA-PAI-1] complexes in rat liver in vivo and in vitro. After intravenous injection into rats t-PA-PAI-1 complexes were rapidly removed from the plasma and the liver took up 80% of the injected dose. Within the liver parenchymal and endothelial liver cells contributed mainly to the uptake of t-PA-PAI-1, and were responsible for 62% and 24% of the liver uptake, respectively. The interaction of t-PA-PAI-1 with isolated rat parenchymal liver cells was of high affinity (Kd 17 nM). A well-known antagonist of the alpha 2-macroglobulin receptor (alpha 2MR/low-density lipoprotein receptor-related protein (LRP), GST-39kDa protein (GST-39kDaP) efficiently inhibited the binding (IC50 0.7 nM) of t-PA-PAI-1 to rat parenchymal liver cells. The interaction of t-PA-PAI-1 with LRP on rat parenchymal liver cells was not Ca2(+)-dependent and is most probably mediated by a specific determinant on PAI-1, since an anti-PAI-1 monoclonal antibody inhibited the binding of t-PA-PAI-1, where as free t-PA did not. The binding of t-PA-PAI-1 to rat hepatocytes could not be inhibited by a complex of plasmin and alpha 2-antiplasmin nor by various other ligands of LRP like beta-VLDL and lactoferrin. Binding of t-PA-PAI-1 to rat parenchymal liver cells was followed by internalization and subsequent degradation in the lysosomal compartment. It is concluded that parenchymal and endothelial liver cells mediate the removal of t-PA-PAI-1 complexes from the circulation. LRP on rat parenchymal liver cells is responsible for the uptake and degradation of t-PA-PAI-1 and may therefore be important for the regulation of the t-PA levels in the circulation.
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PMID:Characterization of the interaction of a complex of tissue-type plasminogen activator and plasminogen activator inhibitor type 1 with rat liver cells. 860 13

The concentrations of matrix metalloproteinase-1 (MMP-1), matrix metalloproteinase-8 (MMP-8), matrix metalloproteinase-9 (MMP-9), lactoferrin and urokinase plasminogen activator (uPA), tissue-type plasminogen activator (tPA) and the inhibitors, tissue inhibitor of metalloproteinase-1 (TIMP-1), plasminogen activator inhibitor-1 (PAI-1), plasminogen activator inhibitor (PAI-2), and alpha2-macroglobulin in the synovial fluids of patients with rheumatoid arthritis was determined before and during chemical synoviorthesis with a sodium salt of the fatty acids from cod-liver oil (Varicocid). Synovial fluids were obtained before treatment from 37 patients with rheumatoid arthritis and, in most cases, at 8 and 24 h after injection of the agent. Well-established ELISAs were used to determine the amounts of all proteins. All patients with rheumatoid arthritis revealed very high levels of metalloproteinases (about 1-15 mu g/ml) in their synovial fluids. During the inflammation inducing treatment the granulocyte enzymes increased. In contrast to this, the level of MMP-1 decreased. All granulocyte-derived enzymes were strongly correlated with each other, whereas their dependence on the granulocyte count was only weak. uPA and PAI-2 showed good correlations with the granulocytes-derived enzymes, but were also only weakly correlating with the cell counts. t-PA was not detected by the ELISA used. The proteases, MMP-8, MMP-9 and uPA were increased 8 h after the treatment, whereas the specific inhibitors TIMP-1, PAI-1 and PAI-2 showed significant changes only 24 h after the injection. Matrix metalloproteinases are important factors in the pathogenesis of rheumatoid arthritis. The inflammatory activity in the joint could be better correlated to the granulocyte enzymes than to the granulocyte counts. The levels of uPA and PAI-2 are also parallel to the granulocyte enzyme levels and might underly the same regulatory mechanism.
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PMID:Determination of metalloproteinases, plasminogen-activators and their inhibitors in the synovial fluids of patients with rheumatoid arthritis during chemical synoviorthesis. 891 99

To determine the role of tumor necrosis factor (TNF) in lipopolysaccharide (LPS)-induced inflammation, 12 healthy subjects received an intravenous injection with LPS (2 ng/kg) preceded by infusion of either a recombinant human dimeric TNF receptor type II-IgG fusion protein (TNFR:Fc; 6 mg/m2; n = 6) or vehicle (n = 6) from -30 minutes to directly before LPS injection. LPS elicited a transient increase in plasma TNF activity, peaking after 1.5 hours (219 +/- 42 pg/mL; P < .05). Infusion of TNFR:Fc completely neutralized endogenous TNF activity. LPS administration was associated with an early activation of fibrinolysis (plasma concentrations of tissue-type plasminogen activator, plasminogen activator activity, and plasmin-alpha2-antiplasmin complexes), followed by inhibition (plasma plasminogen activator inhibitor type I), changes that were completely prevented by TNFR:Fc. By contrast, TNFR:Fc did not influence LPS-induced activation of coagulation (plasma levels of prothrombin fragment F1 + 2 and thrombin-antithrombin III complexes). TNFR:Fc strongly inhibited endothelial cell activation (plasma levels of soluble E-selectin), modestly reduced neutrophil responses (neutrophilia and plasma concentrations of elastase-alpha1-antitrypsin complexes and lactoferrin), but did not affect the release of secretory phospholipase A2 or lipopolysaccharide-binding protein (P > .05). Infusion of TNFR:Fc only (without LPS) in another 6 normal subjects did not induce any inflammatory response. These data indicate that TNF is involved in only some inflammatory responses to intravenous LPS in humans.
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PMID:Effect of a recombinant dimeric tumor necrosis factor receptor on inflammatory responses to intravenous endotoxin in normal humans. 916 Jun 78

The role of proteolytic hydrolysis of milk proteins in the mammary gland during involution is unknown. The objectives of this study were to determine the activities of plasmin, plasminogen, and plasminogen activator in mammary gland secretions collected during involution and to identify peptides generated by proteolysis of casein and lactoferrin in those secretions. Mammary secretions were collected from Holstein cows on d 7, 14, and 21 of involution and on d 7 postcalving. Activities of plasmin, plasminogen, and plasminogen activator were determined on the defatted, filtered aqueous phase of mammary secretions. Activities of plasmin, plasminogen, and plasminogen activator were significantly higher on d 7, 14, and 21 of involution than were those on d 7 postcalving. Protein fragments resulting from hydrolysis were detected by SDS-PAGE in samples collected on d 7, 14, and 21 of involution, but few protein fragments were observed in samples collected on d 7 postcalving when plasmin activity was low. Immunoblot analysis showed that a number of peptides observed during involution were generated from alpha s-casein (CN), beta-CN, kappa-CN, or lactoferrin. The appearance of peptides from proteins of mammary secretions during early involution was generally correlated with increased plasmin activity. Elevated plasmin activity during mammary involution may be primarily responsible for the observed concurrent hydrolysis of milk proteins in mammary secretions.
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PMID:Proteolysis of milk proteins during involution of the bovine mammary gland. 931 41

Following oral surgery, there are sometimes disturbances in wound healing. It was the aim of this investigation to look for relationships between the composition of saliva and disturbed wound healing. Resting as well as stimulated fasting whole saliva was collected from 96 patients (19 to 53 years of age) prior to oral surgery. Flow rate, pH, standard bicarbonate, total buffer bases, peroxidase, lysozyme, thiocyanate, secretory immunoglobulin A, lactoferrin, total protein, tissue type plasminogen activator, and plasminogen activator inhibitor were determined. The salivary data of eight patients who suffered from disturbed wound healing were compared to the data of 20 randomly selected patients with normal wound healing. Patients with disturbed wound healing revealed increased activities and secretion rates for peroxidase in resting saliva. In stimulated saliva, decreased secretion rates for thiocyanate and total protein were found. Not a single salivary factor was able to discriminate both groups of patients with sufficient accuracy, but with a combination of tissue type plasminogen activator, peroxidase, plus secretory immunoglobulin A measurements from resting whole saliva a clearly improved and acceptable discrimination of the two patient groups was possible. A discriminant function including six salivary factors could be used to completely separate both groups.
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PMID:[Components of antibacterial and fibrinolytic activity of human saliva in normal and disordered wound healing]. 1007 67

The low density lipoprotein receptor-related protein (LRP) is a multifunctional endocytic cell-surface receptor that binds and internalizes a diverse array of ligands. The receptor contains four putative ligand-binding domains, generally referred to as clusters I, II, III, and IV. In this study, soluble recombinant receptor fragments, representing each of the four individual clusters, were used to map the binding sites of a set of structurally and functionally distinct ligands. Using surface plasmon resonance, we studied the binding of these fragments to methylamine-activated alpha(2)-macroglobulin, pro-urokinase-type plasminogen activator, tissue-type plasminogen activator (t-PA), plasminogen activator inhibitor-1, t-PA.plasminogen activator inhibitor-1 complexes, lipoprotein lipase, apolipoprotein E, tissue factor pathway inhibitor, lactoferrin, the light chain of blood coagulation factor VIII, and the intracellular chaperone receptor-associated protein (RAP). No binding of the cluster I fragment to any of the tested ligands was observed. The cluster III fragment only bound to the anti-LRP monoclonal antibody alpha(2)MRalpha3 and weakly to RAP. Except for t-PA, we found that each of the ligands tested binds both to cluster II and to cluster IV. The affinity rate constants of ligand binding to clusters II and IV and to LRP were measured, showing that clusters II and IV display only minor differences in ligand-binding kinetics. Furthermore, we demonstrate that the subdomains C3-C7 of cluster II are essential for binding of ligands and that this segment partially overlaps with a RAP-binding site on cluster II. Finally, we show that one RAP molecule can bind to different clusters simultaneously, supporting a model in which RAP binding to LRP induces a conformational change in the receptor that is incompatible with ligand binding.
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PMID:The second and fourth cluster of class A cysteine-rich repeats of the low density lipoprotein receptor-related protein share ligand-binding properties. 1053 29

Aminoalkyl matrices are used in affinity chromatography of amine oxidases and other proteins with affinity for amino groups. Under appropriate circumstances chromatography on aminoalkyl matrices may yield purification factors around 100 to 1000, and they have been used in affinity purification of many members of the amine oxidase family. Other proteins with affinity for aminoalkyl matrices include thiol ester proteins, lactoferrin, and proteins with lysine-binding kringles (plasminogen, plasminogen activator, apolipoprotein A). The affinity of thiol ester proteins for aminoalkyl matrices is abolished after inactivation of the thiol ester group by reaction with low molecular weight amines including ammonia. Due to this, an ammonium sulphate precipitation step should be included in purification schemes for amine oxidases. The affinity of lactoferrin for aminoalkyl matrices stems from an affinity for the repeating amino groups in glycosaminoglycans, and this explains why lactoferrin requires diamines for efficient elution. The affinity of plasminogen for aminoalkyl groups is exploited in a one-step purification from plasma, and is also utilised in purification schemes for angiostatin, an angiogenesis-inhibiting fragment of plasminogen. Apolipoprotein A is homologous to plasminogen, and also has affinity for aminohexyl columns. The common binding motif for these proteins are lysine-binding kringles. Due to the properties of the amino group itself, aminoalkyl matrices will inevitably also function as anion exchangers, and this must be taken into consideration in the choice of conditions for sample loading, column washing and elution of bound proteins. Depending on the length of the alkyl chain, the matrices also have a potential for hydrophobic interactions. This property has been exploited in the purification of several proteins but must be minimized during affinity chromatography of amine oxidases. In conclusion, aminoalkyl matrices are valuable tools for affinity chromatography of several different proteins, and simple variations of sample pretreatment, sample loading, and column washing and elution conditions allow efficient selective purification of proteins with different affinities for the matrices.
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PMID:Aminoalkyl affinity matrices. 1169 80

Lanoteplase is a recombinant mutant of tissue-type plasminogen activator (t-PA) that was developed with an aim to overcome the drawback of rapid systemic elimination of t-PA. In this study, we examined the disposition profile of lanoteplase in vivo and the kinetics of receptor-mediated endocytosis (RME) of this recombinant t-PA in vitro to kinetically characterize the mechanism(s) underlying its tissue distribution and elimination. Integration plot analysis of the initial-phase tissue distribution in rats revealed a much lower uptake clearance (CL(uptake)) of lanoteplase in the liver than that of t-PA. Rate constants for cell surface binding, internalization, and degradation of lanoteplase were also lower than those for t-PA in primary cultured rat hepatocytes. These results suggest that the improved stability of lanoteplase in vivo could be accounted for by the delay in the RME of this recombinant protein. The CL(uptake) in the liver decreased with coadministration of lactoferrin, a ligand for the low-density lipoprotein receptor-related protein (LRP) and the asialoglycoprotein (ASGP) receptors in normal mice, and in lrpap1((-/-)) mice, which have a hereditary deficiency of LRP; In contrast, CL(uptake) was not affected by mannose, whereas that of t-PA decreased with both ligands and in the lrpap1((-/-)) mice. Thus, the hepatic disposition of lanoteplase seems to be mediated by common specific receptors for t-PA, including LRP and the ASGP receptors, whereas the mannose receptor seems to be only minimally involved in the disposition of lanoteplase.
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PMID:Characterization of the hepatic disposition of lanoteplase, a rationally designed variant of tissue plasminogen activator in rodents. 1717 68

Wall teichoic acids (WTAs) and membrane lipoteichoic acids (LTAs) are the major polyanionic polymers in the envelope of Staphylococcus aureus. WTAs in S. aureus play an important role in bacteriophage attachment and bacterial adherence to certain host cells, suggesting that WTAs are exposed on the cell surface and could also provide necessary binding sites for cationic antimicrobial peptides and proteins (CAMPs). Highly cationic mammalian group IIA phospholipase A(2) (gIIA PLA(2)) kills S. aureus at nanomolar concentrations by an action(s) that depends on initial electrostatic interactions, cell wall penetration, membrane phospholipid (PL) degradation, and activation of autolysins. A tagO mutant of S. aureus that lacks WTA is up to 100-fold more resistant to PL degradation and killing by gIIA PLA(2) and CAMP human beta-defensin 3 (HBD-3) but has the sensitivity of the wild type (wt) to other CAMPs, such as Magainin II amide, hNP1-3, LL-37, and lactoferrin. In contrast, there is little or no difference in either gIIA PLA(2) activity toward cell wall-depleted protoplasts of the wt and tagO strains of S. aureus or in binding of gIIA PLA(2) to wt and tagO strains. Scanning and transmission electron microscopy reveal increased surface protrusions in the S. aureus tagO mutant that might account for reduced activity of bound gIIA PLA(2) and HBD-3 toward the tagO mutant. In summary, the absence of WTA in S. aureus causes a selective increase in bacterial resistance to gIIA PLA(2) and HBD-3, the former apparently by reducing access and/or activity of bound antibacterial enzyme to the bacterial membrane.
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PMID:Wall teichoic acid deficiency in Staphylococcus aureus confers selective resistance to mammalian group IIA phospholipase A(2) and human beta-defensin 3. 1834 49


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