Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.4.21.4 (trypsin)
42,187 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The extracellular matrix of cultured chicken embryo fibroblasts undergoes a number of modifications during the early stages of oncogenic transformation. One alteration is increased production of a small protein (Mr approximately 21,000) which is transiently deposited in the matrix by transforming cells infected with LA24, a temperature-sensitive mutant of Rous sarcoma virus (RSV) (Blenis, J., and Hawkes, S.P. (1983) Proc. Natl. Acad. Sci. U.S.A. 80, 770-774). This protein is a major component of substratum-associated material (material which remains attached to culture dishes after removal of cells with ethylene glycol bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid). Its synthesis is stimulated by transformation of cells with NY68, another ts mutant of RSV, and also by treatment of normal, uninfected cells with the tumor promoter, phorbol myristate acetate. Accessibility of the 21-kDa protein to lactoperoxidase-catalyzed iodination indicates an exposed location within the matrix. The protein binds strongly to the culture dish and/or other matrix components. This interaction can be disrupted by sodium dodecyl sulfate but not by several nonionic detergents, unless beta-mercaptoethanol or KCl (0.5 M) are also present. High concentrations of urea or guanidine hydrochloride also remove the protein from the matrix. The 21-kDa protein is resistant to trypsin, collagenase, and the hydrolytic enzymes associated with cells transformed by the wild-type Prague A RSV but not to Pronase or chymotrypsin. A 21-kDa protein with properties similar to those described above is also detected in the medium and binds to the matrix, suggesting that a potential route of deposition of the 21-kDa protein in the matrix may be via shedding and subsequent interaction with other matrix components.
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PMID:Characterization of a transformation-sensitive protein in the extracellular matrix of chicken embryo fibroblasts. 643 99

A protein antigen, I/II, was purified from cells and culture supernatants of Streptococcus mutans (serotype c) by solubilization in urea followed by ion exchange chromatography and gel filtration. Immunological activity was retained after further purification by preparative sodium dodecyl sulphate--polyacrylamide gel electrophoresis (SDS--PAGE). The sedimentation coefficient was estimated to be approximately 8.7S by sucrose gradient centrifugation. The use of staining procedures, as well as the linear migration of this protein through different concentrations of acrylamide during SDS--PAGE, indicated that the antigen is probably not a glycoprotein. A lower molecular weight protein containing the free antigen I determinant was shown to have extensive homology with intact antigen I/II which implied that the former was a degradation product of the intact 185 000 dalton antigen I/II. Antigen II, although previously defined by its resistance to proteases, could be further digested with trypsin after denaturation by SDS--PAGE. Antigen I/II could not be correlated with a group of glucosyltransferases isolated from whole cells and culture supernatants. The cell surface location of antigen I/II was established by the lactoperoxidase-catalysed iodination of intact cells followed by protein analysis using SDS--PAGE. Previously, the potential importance of antigen I/II has been established by its immunogenicity and capacity to induce a protective immune response against dental caries.
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PMID:Separation and characterization of a protein antigen from cells of Streptococcus mutans. 645 27

Whole cells of representative strains of oral streptococci (Streptococcus sanguis, S. mitis, and S. salivarius) were radiolabeled by the lactoperoxidase method of radioiodination. The labeled polypeptides obtained by extraction of whole cells with boiling sodium dodecyl sulfate were analyzed by polyacrylamide gel electrophoresis and autoradiography. Of the total radioactivity, ca. 70% was released by treating whole cells with trypsin, suggesting that the labeling was confined to proteins located on the cell surface. Most S. sanguis strains studied gave a characteristic banding pattern consisting of a high-molecular-weight (120,000 [120K] to 63K) group of six proteins. Three low-molecular-weight (12K, 16K, and 18K) proteins were also detected in many strains.
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PMID:Cell surface proteins of oral streptococci. 648 Jan 9

When their membrane proteins were labeled with 125I by lactoperoxidase, dividing hepatoma cells lost radioactivity to the medium in a biphasic manner (T1/2 = 16-26 h, greater than 40 h). Lysosomotropic weak bases, chloroquine, and NH4Cl inhibited the rapid phase by 59%. More than 50% of the radioactivity which accumulates in the media from dividing cells during the first 4 h after labeling was trichloroacetic acid-soluble, and was identified as iodotyrosine. Iodotyrosine release from labeled membrane proteins was 60-71% inhibited by lysosomotropic agents chloroquine and NH4Cl as well as the sodium-proton ionophore, monensin. The inhibitory effect of NH4Cl and monensin was reversible. Inhibitors of microtubule and microfilament function and transglutamination had no effect on release of iodotyrosine to the medium, but trypsin-like protease inhibitors, p-aminobenzamidine, tosyl-L-lysine/chloromethylketone, and phenylmethylsulfonyl fluoride, as well as the cathepsin B inhibitor, leupeptin, inhibited by 21-24%. Iodotyrosine release showed a biphasic Arrhenius plot with an activation energy of 17 kcal/mol above but 27 kcal/mol below 20 degrees C. These results indicate that cell membrane polypeptides require a temperature-limiting event as well as passage through an ion-sensitive compartment prior to their complete degradation to constituent amino acids. In contrast to other lysosomal-mediated events, however, iodinated membrane proteins of dividing cells are degraded in a manner insensitive to agents which disrupt the cytoskeleton.
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PMID:Degradation of surface-labeled hepatoma membrane polypeptides: effect of inhibitors. 648 99

We have defined the surface protein antigens on Plasmodium gallinaceum zygotes using radioiodination methods and rabbit anti-zygote serum which blocks transmission of the parasite to Aedes aegypti mosquitoes. Fifteen protein bands (1-15) in the molecular weight range of 40 000-240 000 and one band at the bromophenol blue dye marker were labelled by the lactoperoxidase and IODOGEN (1,3,4,6-tetrachloro-3 alpha,6 alpha-diphenylglycoluril) methods. The localization of these radioiodinated components on the cell surface was confirmed in two ways: (1) They were completely degraded by trypsin or Streptomyces griseus protease treatment of intact viable zygotes. (2) They were immunoprecipitated following incubation of intact zygotes with antibody prior to detergent solubilization. Reactivity with immune rabbit serum demonstrated that the major surface immunogens were components with Mr 240 000, 200 000, 180 000, 80 000, 55 000, 50 000 and the band at the dye marker. A band of Mr 180 000 was shown immunologically to be a host serum protein selectively adsorbed to the zygote surface. The identity of this protein and the significance of its adsorption to the surface of the zygote are unknown.
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PMID:Characterization of antigens on mosquito midgut stages of Plasmodium gallinaceum. I. Zygote surface antigens. 668 83

Mature asexual stages of the malaria parasite Plasmodium Knowlesi synthesize proteins of Mr 180 000-225 000 that are expressed on the outer membrane of infected erythrocytes and which vary antigenically such that different parasite clones are specifically agglutinated with homologous antibody. Other non-agglutinable clones have been prepared which fail to express variant antigen on infected cells. Two agglutinable clones of different variant antigen phenotypes and a non-agglutinable cone were examined to determine the proportion of total malarial proteins represented by variant antigens. Malarial proteins were labelled with various radioactive amino acids and the sodium dodecyl sulphate--polyacrylamide gel patterns for the three clones compared by fluorography. The patterns were indistinguishable, the variant antigens being undetectable in analyses of total malarial proteins. Furthermore, these antigens were not detected by Coomassie Blue-staining of total cellular proteins after electrophoresis. Sodium dodecyl sulphate and Triton X-100 extracts of labelled cells were immunoprecipitated using a panel of sera of defined agglutination specificity. The variant antigens could not be detected in the fluorographic patterns of total malarial antigens immunoprecipitated by these sera. In contrast, after lactoperoxidase catalysed radio-iodination of intact schizont-infected cells, the 125I-variant antigens on the cell surface were identified by demonstrating their accessibility both to antibody and to trypsin with intact cells. Thus, the variant antigens are quantitatively very minor malarial proteins that can only be detected by methods which selectively analyse the subset of proteins on the erythrocyte surface.
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PMID:Protein antigens of Plasmodium knowlesi clones of different variant antigen phenotype. 671 54

The outer membrane of Neisseria gonorrhoeae contains approximately 15 proteins, with 2 or 3 accounting for over 75% of the total protein mass. Samples of outer membrane from strain 2686 T4 analyzed by electrophoresis in 2% polyacrylamide gels revealed a band with an apparent molecular weight of 800,000. The band was protein material, as indicated by trypsin and pronase sensitivity and by L-[3H]proline incorporation. Peptidoglycan, nucleic acids, and carbohydrate were not detected in the band. Dye binding, L-[3H]proline incorporation, and labeling of solubilized outer-membrane proteins with 125I-labeled Bolton-Hunter reagent indicated that the band made up 10 to 13% of the total protein mass of isolated outer membranes. The material in the band was purified by gel filtration and, after reduction and alkylation, quantitatively recovered as subunits with an apparent molecular weight of 76,000. The protein in complex form was exposed at the cell surface, as evidenced by labeling whole cells with 125I by using a lactoperoxidase-catalyzed reaction and with CNBr-activated dextran. Rabbit serum raised against whole 2686 T4 gonococci contained antibody which reacted with the protein complex. The protein complex was detected in all gonococcal strains tested, but its presence could not be demonstrated in several other gram-negative species.
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PMID:High-molecular-weight antigenic protein complex in the outer membrane of Neisseria gonorrhoeae. 676 2

Plasmodium knowlesi merozoites were prepared by the polycarbonate sieving method of Dennis, Mitchell, Butcher & Cohen (1975). Merozoite function was assayed by their attachment to and invasion of rhesus erythrocytes at 37 degrees C. The early merozoites from the culture chamber were the most invasive, although maximum numbers of merozoites appeared later. Merozoites were most stable when incubated at room temperature (23 degrees C). At 37 and 0 degrees C invasiveness rapidly declined to zero. Attachment was rapidly lost at 37 degrees C but was retained at 0 degrees C. Attachment was unchanged in the pH range 6.8--7.9 but invasion was reduced at pH 7.9. The presence of L-fucose, D-galactose, D-glucose, D-mannose, N-acetyl-D-galactosamine or N-acetyl-D-glucosamine did not reduce invasion. Attachment and invasion were greatly reduced or abolished by the presence of 2.5 mM EDTA or EGTA, by lactoperoxidase-catalysed iodination of the merozoites, or by treatment of the merozoites with trypsin at a concentration of 1 micrograms/ml or greater for 10 min at 23 degrees C.
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PMID:Factors affecting the ability of isolated Plasmodium knowlesi merozoites to attach to and invade erythrocytes. 677 38

The surface polypeptides of both cultured and blood forms of Trypanosoma cruzi were iodinated by the glucose oxidase-lactoperoxidase technique. Blood-form trypomastigotes (BFT) isolated form infected mice displayed a major 90,000-Mr component. In contrast, both epimastigotes and trypomastigotes obtained form acellular cultures expressed a smaller 75,000-Mr peptide. Both major surface components were presumably glycoproteins in terms of their binding to concanavalin A-Sepharose 4B. Within a 3-h period, both blood and culture forms synthesized their respective surface glycoproteins (90,000 Mr and 75,000 Mr, respectively in vitro. [35S]methionine-labeled surface peptides were immunoprecipitated with immune sera of both human and murine origin. A panel of sera form patients with chronic Chagas' disease and hyperimmunized mice recognized similar surface peptides. These immunogens were the same components as the major iodinated species. The major BFT surface peptide was readily removed by trypsin treatment of the parasites, although the procedure did not affect the 75,000-Mr peptide from the culture forms. Two-dimensional polyacrylamide gel electrophoresis revealed that the 90,000-Mr peptide found on BFT was an acidic protein of isoelectric point (pI) 5.0, whereas, the 75,000-Mr peptide form culture-form trypomastigotes has a pI of 7.2. The 90,000-Mr component is thought to be responsible for the anti-phagocytic properties of the BFT (1).
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PMID:Trypanosoma cruzi. Surface antigens of blood and culture forms. 678 79

GREGARINES, WHICH ARE PARASITIC PROTOZOA LIVING IN INVERTEBRATES, POSSESS A CORTICAL STRUCTURE SPECIFIC TO THEIR VEGETATIVE STAGE: namely two additional cytomembranes are lying just under the plasma membrane. This cortical complex has been isolated by centrifugation on discontinuous sucrose gradients and characterized chemically. Its integrity was tested by electron microscopy. Ghost proteins were resolved by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. About 30 polypeptides of mol.wt. 15000-300000 were present in this fraction and four glycoproteins were detected after periodate/Schiff staining. Ten major proteins were labelled after lactoperoxidase-catalysed iodination. The GP(2) glycoprotein (41000-49000 apparent mol.wt.) appears to be a major component of the cell surface. Effects of trypsin and Pronase digestion on ghosts and cells were monitored by gel electrophoresis and by electron microscopy. Ghosts treated with low trypsin or Pronase concentrations (10-25mug/ml) became drastically disorganized; many proteins were vigorously attacked in comparison with those of control ghosts. Variations in proteinase-sensitivity of proteins are pointed out. The GP(3) glycoprotein (130000-160000 apparent mol.wt.) seemed to be the only glycoprotein released from the cell surface by trypsin. Whole cells treated under the same conditions or with higher proteinase concentrations (up to 1mg/ml) do not exhibit morphological modifications of the cell surface; furthermore, no discernible cleavage of membrane proteins was indicated by electrophoretograms. It is postulated that cell-surface proteins are protected by the dense carbohydrate cell coat. By using various different methods (change of ionic strength, detergent, denaturing agent, labelling experiment) it was possible to localize several major proteins within the protozoon cortical membranes.
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PMID:The three cortical membranes of the gregarines (parasitic protozoa). Characterization of the membrane proteins of gregarina blaberae. 680 83


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