Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.21.4 (trypsin)
 42,187 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This study investigated the synthesis of membrane antigen (MA) as well as virus capsid antigen (VCA) and early antigen (EA) in Daudi cells which had been superinfected with the P3HR-1 strain of Epstein-Barr virus (EBV) and then treated with trypsin to remove initially absorbed MA-positive material from the cell surface. Synthesis of MA, VCA and EA was completely inhibited by puromycin. A marked reduction in the frequency of MA positive cells was observed in superinfected cells cultured in the presence of either cytosine arabinoside (Ara-C) or phosphonoacetate (PA); however, a small fraction of MA synthesis occurred, suggesting an inhibitor insensitive component in MA, A differential absorption of EBV antibody-positive human serum with the Ara-C treated or untreated infected cells detected two antigenically different components in MA: early (Ara-C insensitive) and late (Ara-C sensitive) MA.
 ...
PMID:Appearance of early and late components of Epstein-Barr virus-associated membrane antigen in Daudi cells superinfected with P3HR-1 virus. 20 65

Investigations were carried out on newly synthesized MA, VCA and EA in Daudi cells superinfected with the P3HR-1 strain of EBV and treated with trypsin to remove previously adsorbed MA-positive material from the cell surface. Synthesis of MA, VCA and EA was completely blocked by puromycin. A marked reduction in the frequency of MA-positive cells was observed in the infected cell cultures in the presence of either Ara-C or PA, but a fraction of the MA-positive cells was insensitive to the inhibitors. Differential absorption of an EBV antibody-positive human serum with Ara-C-treated or -untreated infected cells revealed two antigenically different components of MA: early (Ara-C-insensitive) and late (Ara-C-sensitive) MA. Three of five sera from patients with NPC, but none of five sera from normal adults, showed an apparent 'prozone' phenomenon in their reactivity against late but not early MA.
 ...
PMID:Early and late components of Epstein-Barr virus-associated membrane antigen in superinfected Daudi cells and their reactivity with sera from nasopharyngeal carcinoma patients. 21 21

The binding of human IgE myeloma proteins to 16 human cultured lymphoblastoid cell lines was studied by measuring specific uptake of radiolabeled deaggregated IgE myeloma proteins and/or E-IgE rosette formation. Eight lines, RPMI-8866, Wil-2WT, RPMI-6410, RPMI-1788, RPMI-4265, Clowers, COLO-59 and Victor, bound IgE as shown by at least one of these methods. The lines, RPMI-4098, SCRF-5004, NC-37, Daudi, Raji, P3JHR-1, RPMI-1301 and Molt-4 did not bind IgE. Of the positive cell lines, 58 to 98% of the cells formed E-IgE rosetts. The binding of IgE was Fc fragment specific. It could only be inhibited by human IgE and its Fc fragment but not by IgE Fab fragments and Ig of other classes. The binding of IgE also appeared to be species specific, since a rat IgE myeloma protein did neither bind to the cells nor inhibit the binding of human IgE. The binding of IgE was relatively temperature independent and was abolished by trypsin and pronase pretreatment of the cells. Most of the cell lines binding IgE did not bind IgG but had surface immunoglobulin and did not form spontaneous E rosettes. These data suggest that certain lymphoblastoid cells may have receptors for IgE.
 ...
PMID:Binding of IgE myeloma proteins to human cultured lymphoblastoid cells. 79 32

Different leukocytes (Raji, Daudi, Rael lymphoid cells; human peripheral blood lymphocytes, and guinea pig granulocytes), which had been coated with C3 by incubation of 37 degrees C for 20 min in a C3 solution, were demonstrated to form rosettes with erythrocytes coated with complement components (EAC142). The percentage of rosettes was dependent of the amount of C3 present on the cells. Loading of the lymphoid cells with C3 was a time- and temperature-dependent process. C3b was unable to serve the same purposes, although C3 and C3b occupied the C3 receptors on the lymphoid cells to a comparable degree. C3 functions in a similar manner. The C42 enzyme can be replaced by trypsin, so that bridging units may consist of C3 + C42, C5 + C42 OR C3 + trypsin, and C5 + trypsin. Bridging units can be constructed also from C4 + C1. It is suggested that enzymes on one cell liberate labile binding groups of complement components on adjacent cells, thus inducing coupling of the two cells. The possibility is raised that this type of cell interlinkage may play a role in vivo, since there is accumulating evidence that complement components are expressed in the plasma membrane of different cells.
 ...
PMID:Complement bridges between cells analysis of a possible cell-cell interaction mechanism. 92 10

Chimeric proteins composed of ricin toxin A chain (RTA) and staphylococcal protein A (PA) have been produced in E. coli. Constructs consisting of N-terminal RTA and C-terminal PA (RTA-PA) or N-terminal PA and C-terminal (PA-RTA) were capable of binding to immunoglobulin G (via PA) and of specifically depurinating 28 S ribosomal RNA (via RTA). However, neither fusion protein was cytotoxic to antigen-bearing target cells in the presence of an appropriate monoclonal antibody presumably because the RTA could not be released from the PA within the cytosol where the ribosomal substrate of RTA is located. The overcome this, a short amino acid sequence from diphtheria toxin was engineered between the RTA and PA to produce a disulfide-linked loop containing a trypsin sensitive cleavage site. Cleavage of this fusion protein with trypsin converted the RTA-DT-PA to the two chain form consisting of RTA linked by a disulfide bond to PA. The cleaved fusion protein was highly toxic to Daudi cells coated with anti-immunoglobulin antibody suggesting that the RTA could be released from the PA by reduction within the cytosol.
 ...
PMID:Cytotoxicity of a recombinant ricin-A-chain fusion protein containing a proteolytically-cleavable spacer sequence. 212 40

Treatment of monocytes or K562 cells with proteolytic enzymes like pronase or trypsin, increases both the affinity of the type II Fc receptor for IgG and the signaling via this receptor. In the present study we evaluated whether other proteases could similarly enhance Fc gamma RII affinity. We furthermore assessed whether all cell types expressing Fc gamma RII display this effect. Therefore, proteins from the coagulation system and PMN-derived enzymes were tested for effects on Fc gamma RII-mediated ligand binding. Enzymes of the coagulation system were tested both in fibrinogen-depleted plasma, as well as in purified form. No effects were found on Fc gamma RII-mediated rosette formation for both situations. In contrast, supernatant of stimulated granulocytes as well as leucocyte elastase were observed to be active in augmenting EA-hIgG rosette formation of thrombocytes and myeloid cell lines K562 and U937. The B cell lines Raji and Daudi, did not show enhanced rosette formation after enzyme treatment. The active component from granulocyte supernatant was partially characterized as a serine esterase with an apparent Mw of 30 kD. We tested whether the isotype specificity of Fc gamma RII on K562 cells changes upon enzyme treatment. It was found that all three tested murine subclasses gamma 1, gamma 2a, gamma 2b, bound equally well to this receptor, and interaction with all isotypes was enhanced to the same extent.
 ...
PMID:PMN-derived proteases enhance the affinity of Fc gamma receptor II on myeloid cells, but not on B cells. 214 7

In this report, we use 8 different mouse monoclonal antibodies to define 3 immunodominant determinants of the human leukocyte common (LC) antigen, and by defining the relative location and the stability to proteolytic enzymes of these determinants we make some structural predictions about the LC family of molecules. One lineage-restricted determinant is expressed predominantly on B lymphocytes and is located on the two higher (210 and 195) kDa bands of LC, with possibly some expression on the 180-kDa band. The two other determinants, one of which is a complex of 3 partially overlapping sites, are expressed on all leukocytes and found on all four (210, 195, 180, 160 kDa) LC bands. Pronase and trypsin treatment of peripheral blood lymphocytes and of Daudi cells gave complete cleavage of the lineage-restricted determinant from the cells, but the two common determinants were, surprisingly, left intact on the cell surface. By contrast, pronase and trypsin treatment of pure, detergent-solubilized LC resulted in rapid degradation of the common determinants, while the restricted determinant was sensitive to pronase but not to trypsin. Purification of the LC molecule from pronase-treated Daudi cells yielded a 130-kDa lentil lectin-binding protein, while undegraded LC from Daudi cells has a molecular mass of 210 kDa. Our results demonstrate that both common and restricted determinants are at least partly protein in nature and that the restricted determinant is external to and therefore on the presumed amino terminal side of the common determinants. Moreover, because LC has been reported to have a large (approximately 100 kDa) intracellular component, our data suggest the presence of a relatively small (approximately 25 kDa) membrane proximal domain containing both of the common LC determinants and at least one N-linked oligosaccharide chain. This domain is potentially susceptible to proteolytic cleavage, but it is interesting that on the intact cell it is both protected from proteolytic degradation and unable to be cleaved from the cell surface.
 ...
PMID:Structural implications of the location and stability to proteolytic enzymes of immunodominant determinants of the human leukocyte common molecule. 242 43

In this report we describe the production and characterization of a monoclonal antibody to the human promyelocytic leukemia cell line HL-60. The antibody, NC-2, is of the IgG1 subclass and precipitates a 50-Kd protein from 125I-labeled HL-60 cells. The antigen is insensitive to treatment with trypsin, papain, or neuraminidase. NC-2 did not react with a number of established human cell lines, including Daudi, Molt-4, K562, U937, KG-1, CEM, Raji, and Gash-P. Neutrophils and monocytelike cells derived from HL-60 cells that were induced to differentiate continued to express the antigen. NC-2 reacted with all peripheral-blood cells except erythrocytes from eight (5%) of 150 normal individuals tested. Bone marrow samples from patients with myelogenous leukemias were more frequently reactive with NC-2 than were those from normal individuals (12/33 v 1/10). Family studies indicated that the antigen was inherited in an autosomal-dominant manner. These findings suggest that the expression of the above alloantigen is associated with an increased incidence of leukemia.
 ...
PMID:Identification of a leukocyte alloantigen with a high-frequency expression in leukemia patients. 291 90

A recently recognized unique cytotoxic substance, CTS-51, was tested for the hear or acid stability, trypsin digestion and dialysis. Moreover, influences of elevated incubation temperatures or serum concentrations of medium on the cytotoxic activity of CTS-51, and the combination effects of CTS-51 and human leucocyte interferon (HuIFN-alpha (Le)) were investigated. The cytotoxic activity of CTS-51, which is promoted by a small molecule easily passable the dialysis membrane, was found to be very stable to heat (even at 100 degrees C for 30 min) or acid (pH 2.0 for 24 hr at 4 degrees C) treatments. The treatment with 0.75% trypsin for 1 hr did not diminish the CTS-51 activity. The susceptibility of Daudi lymphoma cells to the antiproliferative action of HuIFN-alpha (Le) was further potentiated by treating the cells with CTS-51 for 16 hr. On the other hand, the CTS-51 activity which was revealed to be prescribed by its concentration in the medium, was not potentiated at 39 degrees C when compared to that at 37 degrees C in contrast to HuIFN-alpha (Le) action, and was reduced according to the increase of the fetal calf serum concentration in the medium.
 ...
PMID:A cytotoxic substance (CTS-51) produced by human buffy coat cultures stimulated by staphylococcal enterotoxin B: further characterizations and combined action with interferon. 351 51

The binding of [3H]leucine-labelled pure human interferon alpha from Namalwa cells to human FL and Daudi cells was studied, and evidence obtained to indicate receptor-mediated internalization of interferon. Cell surface-bound and internalized interferons were quantified separately as trypsin-released and unreleased radioactivities, respectively. At 37 degrees C, surface-bound interferon reached a maximum after 1 h and then decreased, while internalized interferon reached a maximum after 2 h. At 21 degrees C, in contrast, surface-bound interferon reached a maximum after 2 h and did not decrease thereafter; no internalization was observed. The same was true at 37 degrees C in the presence of NaF, indicating dependence of internalization on temperature and energy. In control cultures at 37 degrees C, internalized interferon, after reaching a maximum, decreased after prolonged incubation, and concomitantly acid-soluble radioactivity appeared in the culture medium. The decrease in internalized interferon and the emergence of degraded interferon were inhibited by the lysosomotropic agents, ammonium chloride and chloroquine. The fate of labelled interferon, bound to the cell surface of FL cells at 21 degrees C was studied at 37 degrees C, and the results indicated that trypsin-unreleased interferon was derived from the surface-bound interferon, and was secreted in part into the culture fluid in a degraded form upon prolonged incubation. The relation of internalization of interferon to its biological activity was studied in three ways. In FL cells, the antiviral activity was not induced when internalization of interferon was entirely blocked (at 21 degrees C or in the presence of NaF at 37 degrees C). In Daudi cells, both 2'-5'-oligoadenylate (2-5A) synthetase induction by interferon and internalization of interferon were inhibited completely by diethyldithiocarbamate (DDC), whereas in the case of FL cells, DDC inhibited neither 2-5A synthetase induction nor internalization of interferon. Raji cells, which have an interferon-specific binding site on the cell surface but are insensitive to interferon, were found not to internalize interferon, whereas other Burkitt's lymphoma cells, Daudi and Namalwa, which are sensitive to interferon, did internalize it. These findings suggest (but do not prove) that internalization is required for the establishment of interferon activity.
 ...
PMID:Cell surface receptor-mediated internalization of interferon: its relation to the antiviral activity of interferon. 619 40


1 2 Next >>