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)

We studied the mechanisms of platelet activation by sublines exhibiting different metastatic potential of two murine experimental tumors: sublines M4 and M9 of the benzopyrene-induced mFS6 sarcoma and sublines B77-AA6 and B77-3T3 of RSV-transformed BALB/c 3T3 fibroblasts. The neoplastic cells of both models induced platelet aggregation, secretion and prostaglandin biosynthesis. In the first model but not in the second, all these processes correlated with the in vivo malignancy of cells. Pretreatment of B77-AA6 and B77-3T3 cells with apyrase significantly decreased platelet aggregation, while pretreatment of M4 cells was ineffective. However, pretreatment with trypsin or neuraminidase was effective in reducing platelet aggregation induced by M4 cells, but not that induced by any of the others; furthermore, phospholipase A2 reduced the platelet response by all sublines. Finally, platelet-activating activity was also found in the pellets obtained following centrifugation of culture media. These results suggest that platelets are stimulated by cancer cells through different mechanisms; platelet activation by a sialo-lipo-protein complex of the cellular membrane was found to be characteristic of the model in which the platelet-aggregating activity of neoplastic cells correlated with their in vivo metastatic behavior.
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PMID:Characterization of the platelet-aggregating activity of cancer cells with different metastatic potential. 373 62

Glycopeptides were removed by trypsin digestion from the surface of control cells and cells transformed by Rous sarcoma virus, murine sarcoma virus, or polyoma virus. After digestion with pronase, the glycopeptides were analyzed by gel filtration. The elution profiles suggest that there are differences in the glycopeptides from the surface of control cells and those from transformed cells.
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PMID:Glycopeptides from the surface of control and virus-transformed cells. 432 50

Chick embryo fibroblast cultures develop fibrinolytic activity after transformation by Rous sarcoma virus (RSV). This fibrinolytic activity is not present in normal cultures, and it does not appear after infection with either nontransforming strains of avian leukosis viruses or cytocidal RNA and DNA viruses. In cultures infected with a temperature sensitive mutant of RSV the onset of fibrinolysis appears after exposure to permissive temperatures and precedes by a short interval the appearance of morphological evidence of transformation. See PDF for Structure The rate of fibrinolysis in transformed cultures depends on the nature of the serum that is present in the growth medium: some sera (e.g., monkey or chicken serum) promote high enzymatic activity, while others (calf, fetal bovine) do not. Some sera contain inhibitors of the fibrinolysin. Based on the effect of a small number of known inhibitors, at least one step of the fibrinolytic process shows specificity resembling that of trypsin. The sera of sarcoma-bearing chickens contain an inhibitor of the fibrinolysin, whereas normal chicken sera do not. For general discussion, conclusions, and summary see the accompanying paper, part II, (J. Exp. Med. 137:112).
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PMID:An enzymatic function associated with transformation of fibroblasts by oncogenic viruses. I. Chick embryo fibroblast cultures transformed by avian RNA tumor viruses. 434 90

By treating populations of simian virus 40 (SV40)-transformed 3T3 cells with concanavalin A, variants have been isolated which are resistant to the killing action of the lectin. The variants (i) resemble 3T3 cells morphologically and in some of their growth characteristics; (ii) are not agglutinated by high concentrations of concanavalin A or wheat germ agglutinin, but can be rendered agglutinable by treatment with low concentrations of trypsin; (iii) bind the same number of concanavalin A molecules as 3T3 or SV3T3 cells; (iv) cannot be transformed by SV40 and are resistant to focus formation after infection with murine sarcoma virus; (v) contain SV40-specific T antigen and RNA and; (vi) yield wild-type SV40 virus after heterokaryon formation with BS-C-1 cells.
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PMID:Variants of simian virus 40-transformed 3T3 cells that are resistant to concanavalin A. 435 2

Murine sarcoma 37 ascites cells were treated with the proteolytic enzymes, trypsin and chymotrypsin, after which cellular deformability and electrophoretic mobility were measured. It was shown that incubation with trypsin increased the ease with which the cells could be deformed without changing electrophoretic mobility, and that diisopropylfluorophosphate (DFP)-trypsin was inactive, a fact which suggests that trypsin-sensitive peptide linkages help to maintain the "tension" at the cell periphery. On the other hand, chymotrypsin reduced cellular electrophoretic mobility without appreciably altering deformability. This suggests that, although chymotrypsin-sensitive bonds do not contribute to "tension," they are in some way associated with charged groups at the cell periphery.
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PMID:Studies on cell deformability. II. Effects of some proteolytic enzymes. 596 77

Gazdar-murine sarcoma virus (Gz-MSV) particles, obtained from tissue culture fluids of chronically infected HTG-2 hamster cells are immature in morphology and contain uncleaved Pr65gag as the predominant protein (greater than 95% Coomassie blue stain) (A. Pinter and E. deHarven, 1979, Virology 99, 103-110; Y. Yoshinaka and R. B. Luftig, 1982, Virology 118, 380-388). When Gz-MSV particles are disrupted in 1% sodium dodecyl sulfate (SDS) and then analyzed by SDS-polyacrylamide gel electrophoresis (PAGE) in the absence of reducing agents, such as beta-mercaptoethanol (beta-MSH) almost half of the Pr65gag Coomassie blue-stained band is detected as a band at a Mr of 130K. Electrophoretic blotting studies with monospecific antisera against MuLV p30, p15, p12, and p10 showed that the 130K band cross-reacted with all four antigens suggesting that it was a dimer of Pr65gag. Two-dimensional (2D) SDS-PAGE where the first dimension was run under nonreducing conditions and the second with beta-MSH, supported the contention that the 130K band was a dimeric complex of Pr65gag. One also saw minor amounts of a 260K and higher polymeric forms of Pr65gag on the SDS gels, suggesting that polymeric forms may exist as well. When 32P-labeled Gz-MSV particles obtained by in vivo labeling of infected HTG-2 cells with [32P]PPi were electrophoresed on SDS-PAGE, only 10% of the 32P label was detected at the 130K position. In contrast, 30% of the Coomassie blue-stained Pr65gag material was found at 130K on the 2D gels. This suggests that unphosphorylated Pr65gag is more likely to participate in dimer formation than phosphorylated Pr65gag. Pr65gag of Moloney murine leukemia virus (M-MuLV), which is present as a minor (5% of stain) protein band on SDS-PAGE also showed 130K dimers. Further, in beta-MSH-deficient SDS preparations of Gz-MSV, electrophoresed after trypsin treatment, a 32K band that stained with p15, but not p10, p12, nor p30, antisera was observed. If beta-MSH was added, this band was no longer present. Thus Pr65gag dimerization in immature MuLV particles appears to at least involve the p15 region of the polyprotein. Since p15 is an extremely hydrophobic protein, formation of Pr65gag dimers may occur when virion precursor proteins are brought to the cell membrane during virus assembly.
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PMID:Murine retrovirus Pr65gag forms a 130K dimer in the absence of disulfide reducing agents. 608 46

In the present work we show that sarcoma and normal hamster tissues contain a protein which agglutinates normal and transformed cells. The inhibition of agglutination by galacturonic acid and occasionally by fucose suggests a resemblance of this protein with vegetal lectins. When added 5 h after interferon, the crude semipurified and electrophoretically homogeneous preparations reduce within 20 h the antiviral state pre-established by interferon. These two biological tests have enabled us to monitor the subsequent purification steps. The isolation of the biologically active protein is greatly facilitated by its resistance to pepsin and nucleases, whereas its sensitivity to trypsin and Pronase suggests its proteinaceous character. Furthermore, the molecule is stable when heated 1-2 min at 100 degrees C in the presence or absence of sodium dodecyl sulfate. After pepsin treatment, Sephacryl G-200 gel filtration, and ion exchange chromatography on DEAE-cellulose, 25-40-fold purification can be obtained. When controlled by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, a double band (DEAE-cellulose sample) or single band (octyl-agarose sample) is detected in the 65,000-dalton region and no other contaminator is present. The eluted protein retains full biological activity when assayed by the degradation of the interferon-induced antiviral protection in the cell or titrated by cell agglutination.
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PMID:Sarcolectin: an interferon antagonist extracted from hamster sarcomas and normal muscles. Isolation, characterization, and purification. 619 52

Intermediate-sized filaments have been noted in epithelioid sarcoma by previous investigators, two of whom have reported that the filaments represent vimentin. We utilized polyclonal antibodies directed against keratin and immunoperoxidase techniques (PAP) to stain 32 of the more than 300 cases accumulated at the AFIP . All of our material was formalin-fixed, paraffin-embedded. Seventy-five percent of our cases (24/32) showed positive immunoreactivity, a feature that may be of diagnostic help in distinguishing epithelioid sarcoma from modular fasciitis, benign and malignant fibrous histiocytoma, malignant melanoma, and necrotizing granuloma. In these cases, the reaction was enhanced using predigestion with trypsin. The immunoreactivity varied from tumor to tumor, perhaps due to formalin fixation. Since synovial sarcoma and mesothelioma may also be cytokeratin-positive, our findings indicate that keratin immunoreactivity is not confined to epithelial tumors and may also occur in neoplasms traditionally regarded as mesenchymal.
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PMID:Keratin in epithelioid sarcoma. An immunohistochemical study. 620 17

Antibodies in human sera from healthy individuals were shown to be reactive with highly purified 70,000-dalton envelope glycoprotein (gp70) of the simian sarcoma virus-simian sarcoma-associated virus (SSV-SSAV) complex in radioimmunoprecipitation assays under certain conditions. The specificity of the reaction was analyzed in absorption tests with normal human serum proteins, assays of viral gp70 antigenicity after exposure to exo- and endoglycosidases or trypsin, and carbohydrate hapten inhibition studies. On the basis of the results obtained in these experiments we have concluded that immune recognition of SSV-SSAV gp70 can be mediated by naturally occurring heterophil antibodies in human sera that are reactive by virtue of binding to the carbohydrate moiety of the viral gp70 molecules. The results are consistent with the idea that the antibodies in question are elicited as a result of exposure to many natural substances possessing widely crossreacting antigens and are not a result of widespread infection of man with replication-competent oncoviruses.
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PMID:Specificity of human antibodies to oncovirus glycoproteins: recognition of antigen by natural antibodies directed against carbohydrate structures. 624 96

Polypeptides characterized by their ability to confer a transformed phenotype on an untransformed indicator cell have been isolated directly from tumor cells growing both in culture and in the animal, by using an acid/ethanol extraction procedure. Assay of these polypeptides is based on their ability to induce normal rat kidney fibroblasts to form colonies in soft agar. Peptides from murine sarcoma virus-transformed mouse 3T3 cells grown in culture had the highest specific activity in this assay; peptides from sarcomas produced from these cells or from chemically induced transplantable bladder carcinomas of mice were one-third as active; and peptides from a chemically induced rat tracheal carcinoma had only one-tenth the activity. Treatment with either trypsin or dithiothreitol destroyed the activity of all of these materials. The properties of these intracellular polypeptides from both virally and chemically transformed cells are similar to those described for the sarcoma growth factors (SGFs) previously isolated from the conditioned medium of sarcoma virus-transformed mouse 3T3 cells, suggesting the definition of a class of transforming growth factors common to tumor cells of different origins. The transforming peptides from the cultured sarcoma virus-infected cells were separately by gel filtration into two fractions of apparent molecular weight 7000 and 10,000. The major fraction at molecular weight 7000 represented approximately 0.1% of the original cell protein and had a specific activity 50 times that of the original acid/ethanol extract.
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PMID:Transforming growth factors: isolation of polypeptides from virally and chemically transformed cells by acid/ethanol extraction. 625 62


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