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)

Recently, it has been shown that the N-terminal peptide from a new type of thrombin receptor exhibits thrombin receptor agonist activity. We examined the effects of this synthetic thrombin receptor against peptide (SFLLRNPNDKYEPF, TRAP) on human umbilical vein endothelial cells (HUVECs). TRAP induced rapid morphological changes in HUVECs, with marked increase in the release of prostacyclin, endothelin, platelet activating factor, tissue type plasminogen activator, and plasminogen activator inhibitor-1. Incubation of cells with TRAP also induced a rapid decrease in cell-surface thrombomodulin. Thus, activation of the newly described thrombin receptor may alter their role in the hemostatic pathway.
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PMID:Thrombin receptor agonist peptide decreases thrombomodulin activity in cultured human umbilical vein endothelial cells. 814 69

Seven peptides were synthesized to analyze the mechanism of the intramolecular binding of the N-terminal peptide of Glu-plasminogen (Glu-plg) to its kringles. They were Ala44-Lys50, Ala44-Glu51, Ala44-Ser49, Val17-Gly23, Lys19-Gly23, Lys19-Gln21 and Lys19-Lys20. Ala44-Lys50, Ala44-Glu51 and Lys19-Lys20.enhanced the activation of Glu-plg by tissue plasminogen activator (t-PA) or urinary plasminogen activator (u-PA). The activation of Lys-plg, however, was not influenced by these peptides. Therefore, it is suggested that these three peptides worked on Glu-plg in a similar manner as lysine analogue by making the conformation of Glu-plg looser. These peptides did not have any direct effects on u-PA and t-PA. Concerning the effect on fibrinolysis Ala44-Lys50 and Lys19-Lys20 prolonged euglobulin clot lysis time. These results indicate that Ala44-Glu51 may be a responsible binding site in the N-terminal portion of Glu-plg, and LBS of kringle 1 or 4 is the binding site of N-terminal portion of Glu-plg.
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PMID:Conformational change of plasminogen: effects of N-terminal peptides of Glu-plasminogen. 839 30

Streptokinase, an extracellular protein produced by Streptococci, is capable of activating the human fibrinolytic zymogen plasminogen. The rate of amidolytic activity of the plasminogen-streptokinase complex is greatly diminished by micromolar concentrations of ATP and heparin oligosaccharides. In addition, the plasminogen activator activity of the plasminogen-streptokinase complex is also inhibited by these effectors. ATP and heparin oligosaccharides show structural similarity, suggesting that the inhibition is caused by binding of these molecules to a common newly formed binding pocket in streptokinase, which appears after interaction with plasminogen. Addition of the bivalent cations Ca2+ and Mg2+ reverses the inhibition caused by ATP and heparin. In the presence of ATP and bivalent cations, the complex between plasminogen and streptokinase develops an autophosphorylating activity whose target is the sequence LTSRPAHG in the 4.5 kDa streptokinase N-terminal peptide, which is an early autolysis peptide. This streptokinase N-terminal peptide, which is essential for streptokinase activating activity, may serve, once phosphorylated, in mechanisms related to the pathogenicity of Streptococci. These studies suggest a critical role for plasminogen in regulating the activity of the streptokinase molecule.
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PMID:ATP-regulated activity of the plasmin-streptokinase complex: a novel mechanism involving phosphorylation of streptokinase. 854 80

Streptokinase(SK), a plasminogen activator, is known to have multi-domain structure. The function of the C-terminal region of streptokinase was investigated with SK mutants constructed by truncating 26, 33, 37, 40, 41, 46, 47, 70 or 97 amino acid residues from the C-terminus. The truncated SKs were expressed in E. coli and purified. The 41 residue deletion (SKP373) from the C-terminus had not effect on the plasminogen activation activity. However, the deletion of 46 amino acid residues (SKP368) resulted in the dramatic reduction of the plasminogen activation efficiency. The result suggests that the C-terminal peptide from Met369 to Pro373 of SK may play an important role on the plasminogen activation.
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PMID:C-terminal peptide of streptokinase, Met369-Pro373, is important in plasminogen activation. 895 83

beta2-Glycoprotein I (beta2GPI) is a highly glycosylated plasma protein with the ability to bind negatively charged substances such as DNA, heparin, dextran sulfate, and negatively charged phospholipids. The most relevant physiological role of beta2GPI is supposed to be the regulation of the function of anionic phospholipids like cardiolipin (CL). beta2GPI consists of a single polypeptide chain (326 amino acid residues) with a molecular mass of about 50 kD and with five tandem repeated domains (I, II, III, IV, and V). In the previous study, we found that factor Xa can produce the nicked form by cleaving Lys 317-Thr 318, using recombinant human domain V (r-Domain V). However, the reaction was extremely slow. In the present paper, we found that plasmin can produce the nicked form of domain V, using recombinant domain V (r-Domain V) and beta2GPI from human plasma. On sodium dodecyl sulfate-polyacrylamide gel electrophoresis, r-Domain V was rapidly cleaved into a nicked form by plasmin, very slowly by factor Xa, but not by thrombin, tissue-type plasminogen activator, urokinase, and tissue factor/factor VIIa. The cleavage site of r-Domain V and beta2GPI by plasmin was proved to be Lys 317-Thr 318 by amino acid sequence analysis of the digest and of the C-terminal peptide isolated by high-performance liquid chromatography. The cleavage was completely inhibited by plasmin inhibitor (alpha2PI). The nicked form was demonstrated to show reduced affinity for CL with a dissociation constant of one order of magnitude larger than that of the intact beta2GPI. To determine whether the specific cleavage of beta2GPI by plasmin can occur also in plasma, human plasma was first acid-treated to inactivate alpha2PI and then incubated with urokinase. About 12% of beta2GPI in plasma was nicked when alpha2PI activity decreased to 80%. The nicked form was not generated in plasminogen-depleted plasma. These results suggest that plasmin can produce the nicked form of beta2GPI with the reduced ability to bind phospholipids in vivo.
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PMID:Plasmin can reduce the function of human beta2 glycoprotein I by cleaving domain V into a nicked form. 959 64

We have studied the influence of Gly-Ala-Arg peptide at the N-terminus and the oligosaccharide at Asn184 on the clearance of tissue plasminogen activator (t-PA). In order to intensify the influence of these structural features, Gln117 t-PA, which is a mutant tissue plasminogen activator (mt-PA) expressed in mouse C127 cells, was used for the investigation. It is altered to remove a high mannose type oligosaccharide by the mutation of an amino acid from Asn117 to Gln. We isolated 4 variants of Gln117 t-PA by cation-exchange chromatography, which are abbreviated as S-I, S-II, L-I and L-II. These variants originated from the heterogeneity of the peptide chains (S-chain, 527 amino acids, L-chain, 530 amino acids) and oligosaccharide (Type I, 2 oligosaccharides, Type II, 1 oligosaccharide). Pharmacokinetics of these variants were investigated after single intravenous administration to male rats at a dose of 250 microg/kg. Significant differences in pharmacokinetic parameters were observed among these variants, but there was no considerable difference in fibrin clot lysis time (FCLT) activity. Gly-Ala-Arg peptide at the N-terminus increased the CLt, whereas the oligosaccharide at Asn184 decreased the CLt. Moreover, the effects of the N-terminal peptide and the oligosaccharide on the CLt were independent of each other. Our study with Gln117 t-PA revealed the role of the N-terminal peptide found in the L-chain produced during the processing of t-PA precursor.
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PMID:Influence of N-terminal peptide and oligosaccharide on the clearance of t-PA. 1078 31

Previously, we obtained a protein that has considerable amino acid sequence homology with secretory phospholipase A(2) (PLA(2)) from a bullfrog pituitary fraction obtained during the purification of thyrotropin (TSH). Subsequently, partial amino acid sequence (N-terminal 45 amino acid residues) analysis revealed this protein to be identical to the N-terminal amino acid sequence of otoconin-22, the major protein of aragonitic otoconia in the Xenopus saccule. In this study we developed an antibody against the N-terminal peptide of the bullfrog protein and applied it for immunocytochemical study of the pituitary and its surrounding tissue. Western blotting analysis showed that this antibody recognizes a 20.4-kD protein that has a molecular mass close to that of otoconin-22. Immunohistochemical reaction with the antibody was not found in any anterior pituitary cells but was intense in the monolayer epithelial cells of the endolymphatic sac surrounding the pituitary gland, which is a major storage site of calcium carbonate in amphibians. An electron microscopic study revealed that the cuboidal cells in the endolymphatic sac contained large, polymorphic secretory granules in their apical cytoplasm. Immunogold particles indicating the presence of a PLA(2)-like protein were observed predominately in these secretory granules. These findings support the view that this PLA(2)-like protein obtained during purification of TSH was derived from the endolymphatic sac adhering to the pituitary and that this protein is a bullfrog otoconin. (J Histochem Cytochem 49:631-637, 2001)
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PMID:Immunocytochemical localization of secretory phospholipase A(2)-like protein in the pituitary gland and surrounding tissue of the bullfrog, Rana catesbeiana. 1130 1

Many bacterial pathogens secrete proteins that activate host trypsinogen-like enzyme precursors, most notably the proenzymes of the blood coagulation and fibrinolysis systems. Staphylococcus aureus, an important human pathogen implicated in sepsis and endocarditis, secretes the cofactor staphylocoagulase, which activates prothrombin, without the usual proteolytic cleavages, to directly initiate blood clotting. Here we present the 2.2 A crystal structures of human alpha-thrombin and prethrombin-2 bound to a fully active staphylocoagulase variant. The cofactor consists of two domains, each with three-helix bundles; this is a novel fold that is distinct from known serine proteinase activators, particularly the streptococcal plasminogen activator streptokinase. The staphylocoagulase fold is conserved in other bacterial plasma-protein-binding factors and extracellular-matrix-binding factors. Kinetic studies confirm the importance of isoleucine 1 and valine 2 at the amino terminus of staphylocoagulase for zymogen activation. In addition to making contacts with the 148 loop and (pro)exosite I of prethrombin-2, staphylocoagulase inserts its N-terminal peptide into the activation pocket of bound prethrombin-2, allosterically inducing functional catalytic machinery. These investigations demonstrate unambiguously the validity of the zymogen-activation mechanism known as 'molecular sexuality'.
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PMID:Staphylocoagulase is a prototype for the mechanism of cofactor-induced zymogen activation. 1452 51