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 sedimentation of radiolabelled 22 nm hepatitis B surface antigen particles was unaffected by treatment with either trypsin or SDS alone, but combined treatment disrupted the particulate nature of the radiolabelled material. Considerable antibody binding activity by the group-specific determinant (a) was preserved after combined SDS and trypsin treatment but was released from the bulk of the radiolabelled protein; gel filtration indicated an approximate mol. wt. of 5000 to 15000 for the released antibody binding material. This material was precipitated by concanavalin A, suggesting the presence of carbohydrate. Its serological activity was remarkably resistant to boiling and to proteolytic digestion, but was partially sensitive to treatment with 0-01 M-periodate or with mixed carbohydrases and neuraminidase, and was greatly reduced by treatment with reducing agent. These data suggest that the stability of the a determinant is due to the structure of the antibody binding site itself, rather than to involvement in the quaternary structure of the particle, and that intact disulphide bonds and carbohydrate, closely related to the antibody binding site, are necessary for the full expression of serological acitivity.
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PMID:Tryptic cleavage of antibody binding sites from hepatitis B surface antigen particles. 6 23

It was previously shown that the fibroblast surface antigen (SF antigen, SFA) is composed of polypeptides of high molecular weight 210,000 (SF210) and 145,000 (SF145) and that both of these decrease in quantity after transformation of the fibroblasts by Rous sarcoma virus (RSV). The present experiments show that SF210 is a glycoprotein. It is accessible to surface labelling by lactoperoxidase catalyzed iodination. The SF210 molecule is highly susceptible to trypsin on cell surface. Anti-SFA antibodies specifically precipitated the surface labelled polypeptide. The lactoperoxidase iodinated SF210 polypeptide was greatly reduced in cells transformed by RSV. It is concluded from these studies that the large external transformation sensitive (LETS) protein detected by other workers is the same molecule as SF210. Part of the label of surface iodinated fibroblasts did not enter the polyacrylamide gels. This high molecular weight material is also susceptible to trypsin treatment and decreases in quantity after transformation by RSV. The data suggest that it may be antigenically related to SF protein. Treatment of surface of 35S-methionine-labelled cultures with trypsin in concentrations able to initiate proliferation of density-inhibited cells rapidly released SF210 from fibroblast surface. A single high molecular weight polypeptide (mol. wt about 200,000, SF200) was detected in the culture medium. SF210 may thus be a major target molecule of trypsin action. Treatment of cultures with insulin that also stimulated the fibroblasts to initiate proliferation did not result in any detectable alteration in the external glycoprotein SF210. It is concluded that although release of SF210 may be a sufficient trigger to stimulate proliferation in stationary cells, this molecule appears not to be directly involved in initiation of fibroblast proliferation from the G1 (or G0) phase of the cell cycle.
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PMID:Fibroblast surface antigen (SF): the external glycoprotein lost in proteolytic stimulation and maligant transfromation. 17 31

Primary cell cultures of mammary tumors from Rill, GR, DD, BALB/cfC3H, and BALB/c mice were prepared by trypsin-EDTA dissociation of tumors. Cultures from these strains contained predominantly cells of epithelial morphology which formed three-dimensional domelike structures. Cultures from Rill, GR, DD, and BALB/cfC3H tumors produced extra-cellular type-B mouse mammary tumor virus(es) (MuMTV), either in the absence of detectable type-C virus or with less than 1% contamination with type-C virus. This was determined by radioimmunoassays for MuMTV and murine leukemia virus (MuLV) antigens. Only BALB/c cultures produced MuMTV with as much as 3% contaminating MuLV. High levels of MuMTV surface antigen were also found in soluble form in culture supernatants. Virus polypeptide analyses by electrophoresis on polyacrylamide gels showed that the Rill BALB/cfC3H, DD, and BALB/c viruses all contained polypeptides characteristic of MuMTV. Primary cultures of mammary tumor cells make available a source of purified MuMTV antigens, structural proteins, and nucleic acids for comparative studies of MuMTV from various mouse strains.
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PMID:Characterization of mouse mammary tumor viruses from primary tumor cell cultures.I. Immunologic and structural studies. 17 73

Surface antigens of HeLaHVJ cells, a cell line persistently infected with HVJ, were studied by fluorescent antibody staining. After absorption with concentrated HVJ virions and HeLa cells, anti-HeLaHVJ antiserum was able to demonstrate specific surface fluorescence on HeLaHVJ cells, while this serum no longer reacted with original HeLa cells nor with HVJ virions. During cytolytic infection of HeLa cells with HVJ, this specific surface antigen appeared at an early stage of infection prior to the appearance of newly synthesized HVJ viral antigens and moreover appeared in spite of the inhibition of viral protein synthesis. This antigen was detected neither on HeLa cells infected with other myxoviruses except HVJ nor on various other kinds of cells infected with HVJ. The specific surface antigen was still found on the HeLaHVJ cell surface after incubation at 38 degrees C for two days, while HVJ structural antigens on the cell surface no longer could be detected. Mild short-term treatment of HeLa cells with trypsin, neuraminidase from vibrio cholerae, phospholipase-C and hyaluronidase failed to expose specific antigen. The antigen was distinguishable from the Forssman and human blood type antigens. The mechanism of appearance of a new antigen on the surface of HeLaHVJ cells remains unclear.
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PMID:Surface antigens on HeLa cells persistently infected with HVJ (Sendai virus). 18 62

Guinea pig macrophages can take up sufficient 2,4 dinitrophenyl guinea pig albumin during a brief in vitro exposure at 37 degrees C to trigger proliferation and lymphokine production with primed T lymphocytes on subsequent co-culture. Treatment of such antigen-bearing macrophages with trypsin, a procedure which removes surface antigen, does not alter the ability of such macrophage to initiate the release of migration inhibition factor from sensitized T lymphocytes. In addition, formation of antigen-specific rosettes between primed T cells and antigen-bearing macrophages is not blocked by high concentrations of antibody directed against the antigen mediating this interaction. Similarly, primed T lymphocyte DNA synthesis induced by antigen-bearing macrophages is not inhibited by specific antibody to that antigen. These data support the conclusion that the fraction of macrophage-associated antigen which is relevant to T lymphocyte activation does not reside on the macrophage surface but rather remains in a restricted compartment from which it is accessible to the T cell but unavailable to either blockade by specific antibody or removal by proteolytic enzymes.
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PMID:Antigen handling by guinea pig macrophages: further evidence for the sequestration of antigen relevant for activation of primed T lymphocytes. 32 35

Relative amount of surface antigen was compared on L 1210 leukaemia cells treated with soluble or insoluble derivatives of trypsin and papain. Trypsin or trypsin insoluble derivative do not change the amount of antigen significantly as compared with control. However, papain insoluble derivative decrease the relative amount of antigen within 45 min to the value of 0.43 or 0.55 respectively as compared with the control specimen.
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PMID:Changes in the relative amount of surface antigens on the living cells after treatment with insoluble protease derivatives. 70 May 4

Adherent, trypsin-resistant, peritoneal cells from mice with chronic schistosomiasis mansoni, and from control mice, were cultivated in vitro up to 20 days. Fibroblasts regularly appeared, about 6 days after seeding, in cultures of the manyfold more numerous cells from infected mice, concomitantly with a dramatic increase, detected by autoradiography, in the percentage of DNA-replicating cells of the monocyte-macrophage lineage. Peritoneal cells from healthy and from infected mice were fractionated on discontinuous Percoll gradients. Eight cell subsets were harvested in both cases, quantitated, and studied by electron microscopy. Two fractions (2 and 3: 1.041 < densities < 1.060 g/ml) from infected mice were greatly enriched in monoblasts and promonocytes. The cells of the different subsets were seeded separately, trypsin-treated and cultivated in vitro. Cultures of cell fractions 2 and 3 from infected mice contained the majority of the DNA-synthesizing cells and gave regularly rise to fibroblasts. Cultures of the different fractions were used for sequential morphological observations (2-11 days) at the electron microscope level. Early cultures were also used for the ultrastructural detection of the Mac-1 (CD 18/CD 11b) surface antigen by gold immunocytochemistry. A few fibroblasts were rarely observed in cultures of fractions 2 and 3 from control mice, while cells with ultrastructural features of myofibroblasts were regularly observed in cultures of the same fractions harvested from mice with chronic schistosomiasis. Fractions 2 and 3 from infected mice contained a large number of Mac-1 positive monoblasts. The correlations between the presence of monoblasts, DNA replication in cells of the monocyte-macrophage lineage and the appearance of myofibroblasts in cultures of the same fractions derived from infected mice are discussed.
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PMID:A study of peritoneal cells from healthy and Schistosoma mansoni-infected mice with special reference to myofibroblasts arising in culture. 145 34

A specific 135-kDa protein was purified from porcine cauda epididymal fluid. Analysis of its N-terminal amino acid sequence revealed it to be a new protein. Stable clones of hybridomas that produced monoclonal antibodies against the purified 135-kDa protein were established. A clone, B-11, reacting both with epididymal fluid and with sperm plasma membranes was selected and used in this study. Immunoblotting analysis showed that B-11 reacted only with a 135-kDa protein among epididymal fluid proteins. In contrast, B-11 did not recognize a similar 135-kDa sperm protein but did strongly react with a 27-kDa protein among sperm membrane proteins, extracted by NP-40 in the presence of protease inhibitors. B-11 also reacted only with a 27-kDa protein fragment among trypsin digests of the 135-kDa epididymal protein. The 135-kDa protein was first detected, by ELISA or immunoblotting analysis, at the beginning of the corpus epididymis. Maximal levels were reached in the distal corpus and levels were slightly decreased in the cauda epididymis. On the other hand, the surface of caput sperm were found to contain small amounts of antigen(s), the concentration of which gradually increased during epididymal transit. In immunocytochemical studies, the antigen was detectable in the epithelial cells from the initial segment to the corpus of the epididymis but not in the caudal cells. In the lumen, the presence of the 135 kDa protein was apparent in the corpus (at a maximum in the middle and distal corpus) and to a lesser degree in the caudal lumen. The 27-kDa protein was distributed all over the equatorial region of the acrosome of less than 10% of caput epididymal sperm. As sperm passed through the corpus epididymis, the percentage of immunoreactive cells increased and the protein was restricted to specific domains of the sperm head. Thus, on the mature sperm, antigen was localized in a crescent-shaped area of the equatorial segment just behind the anterior part of the acrosome and on the apical rim of the sperm head. This is the first observation of a sperm surface antigen derived from an epididymal protein as a proteolytic fragment that interacts with specific regions of the sperm membrane during the process of spermatozoa maturation.
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PMID:Localization of a maturation-dependent epididymal sperm surface antigen recognized by a monoclonal antibody raised against a 135-kilodalton protein in porcine epididymal fluid. 149 68

Trypanosoma congolense bloodstream forms preincubated with a high titer of anti-variant surface antigen (VSG)-specific antibody, a low amount of anti-VSG plus complement-active mouse serum (MS), MS alone, and trypsin were cocultivated with mouse peritoneal macrophages in vitro. Immunofluorescence as well as transmission and scanning electron microscopy revealed that upon attachment to the macrophages' surface, trypanosomes opsonized with anti-VSG/MS formed opsonized filopodia, which were rapidly internalized by the phagocytes. Although these cells attached as frequently as anti-VSG or trypsin-pretreated parasites, the rate of phagocytosis of anti-VSG/MS pretreated trypanosomes was reduced significantly. Trypanosomes pretreated with high antibody titers alone were lysed on the surface of the macrophages before phagocytosis was completed. Parasites opsonized with complement alone adhered only occasionally and were rarely phagocytosed. Trypsin-treated trypanosomes, which served as positive control cells, rapidly attached and remained intact until ingulfment by the macrophages was completed. Untreated control parasites did not attach to the macrophages and were not phagocytosed. Cocultivation of macrophages with anti-VSG/MS-opsonized trypanosomes caused internalization of the flagellum by membrane fusion. Filopodia formation by T. congolense is thus correlated with a marked reduction in phagocytosis even in the presence of only a sublytic antibody titer.
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PMID:Cell surface interactions between Trypanosoma congolense and macrophages during phagocytosis in vitro. 156 Apr 18

Monoclonal antibodies against infective third-stage larvae (L3) of Brugia pahangi were generated from mice immunized with L3 antigens. The monoclonal antibodies were L3 stage-specific or stage-nonspecific. A BpG1 monoclonal antibody (IgG1 subclass) showing L3 stage-specificity was examined in detail. BpG1 recognized the surface of B. pahangi L3 and also reacted with the surface of Brugia malayi L3 but not with the surface of filarial worms of other genera, such as Acanthocheilonema viteae and Litomosoides carinii. BpG1 promoted cellular adhesion to the surface of B. pahangi L3. BpG1 bound on living L3 was shed but the shedding rate was relatively slow. The surface antigen recognized by BpG1 had a molecular weight of 58 kDa. It was stable to heat and periodate treatments but sensitive to trypsin digestion and was released from living L3 by SDS but not by Triton X-100 or CTAB. Preincubation of L3 with BpG1 significantly reduced the recovery rate of worms compared with the preincubation with a monoclonal antibody (IgG1 subclass) against the inner tissues of B. pahangi L3 or control supernatant of P3U1 myeloma cells. This result suggests that the antigen containing the BpG1 epitope may be one of the targets of a protective immune response against Brugia infection.
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PMID:Brugia pahangi: production of a monoclonal antibody reactive with the surface of infective larvae. 163 60


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