Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.23 (beta-galactosidase)
 14,648 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The BMLF1 region of the Epstein-Barr virus (EBV) genome and the immediate-early (IE) region of human cytomegalovirus (HCMV) both encode proteins which can trans-activate heterologous promoter/chloramphenicol acetyl transferase (CAT) constructs, including a human immunodeficiency virus type-1 promoter/CAT construct. We demonstrate here that this trans-activation by the EBV BMLF1 gene product, which we have previously shown to be largely post-transcriptional, is reporter gene dependent. In contrast, trans-activation by the HCMV-IE gene product(s), previously shown to be mediated at the RNA level, is seen regardless of whether CAT, human growth hormone, or beta-galactosidase is used as the reporter gene. Mutational analysis revealed no specific cis-acting sequences within the HIV-1 promoter which were required for trans-activation by the HCMV-IE gene product(s).
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PMID:Disparate effects of two herpesvirus [corrected] immediate-early gene trans-activators on the HIV-1 LTR. 255 54

Stable human antigen-specific monoclonal B cell lines were established without prior in vivo immunization. This was accomplished by expanding the anti-trinitrophenyl (TNP) B cells in vitro with the antigen TNP-Brucella abortus and then immortalizing them with Epstein-Barr virus. Five anti-TNP clones were selected by sequential limiting dilution. All five anti-TNP clones secreted IgM kappa antibodies. When tested against a panel of self and environmental antigens, all five anti-TNP clones exhibited cross-reactivity with an Escherichia coli-derived beta-galactosidase. To determine whether this was a more general phenomenon, a panel of murine monoclonals were tested and found to bind to beta-galactosidase. It is therefore possible that human and murine anti-TNP beta cell responses reflect reactivity against an environmental antigen, namely an epitope present on E. coli-derived beta-galactosidase. This approach of expanding human antigen-specific B cells by antigen stimulation in vitro, with a T-independent hapten-carrier conjugate before Epstein-Barr virus transformation, may prove useful in the development of human monoclonals for therapeutic purposes.
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PMID:In vitro generated human monoclonal trinitrophenyl-specific B cell lines. Evidence that human and murine anti-trinitrophenyl monoclonal antibodies cross-react with Escherichia coli beta-galactosidase. 282 79

A double-stranded synthetic oligonucleotide that codes for an amino acid sequence specifically recognized and cleaved by the endopeptidase, renin, was inserted into a plasmid expression vector. The double-stranded oligonucleotide was placed at the junction between the sequences coding for two distinct domains of a fusion protein. The vector used for this analysis expressed a 190-kD Epstein-Barr virus membrane antigen (EBV-MA)-beta-galactosidase (beta-gal) fusion protein (Beisel et al., 1985). The resultant novel protein product expressed by the new construction can be cleaved specifically by renin to yield two distinct polypeptides, EBV-MA and beta-gal, corresponding to the two domains of the original fusion protein product.
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PMID:Site-specific cleavage of a fusion protein by renin. 282 77

The protein sequence predicted by the Epstein Barr virus (EBV) BERF4 open reading frame includes a tetrapeptide, Lys-Arg-Pro-Arg (KRPR), shown for other proteins to be a component of a signal for rapid nuclear localization. A subgenomic fragment of EBV DNA containing BERF4 has been incorporated into an expression vector, transfected onto primate cells and the nuclear distribution of the resulting protein established by immunofluorescence using EBV positive human sera. These sera contained high titres of antibodies to a fusion protein, produced in E. coli, consisting of beta-galactosidase and the C-terminal 167 amino acids of BERF4. Immunoaffinity purified antibodies reactive with the EBV component of the fusion show the molecular weight of this antigen in EBV immortalized B-cell lines to be about 160 kD. The demonstration that BERF4 contains an exon encoding a nuclear protein identifies a new EBNA gene (EBNA-6) and suggests that KRPR is a signal sequence common to a number of viral and cellular nuclear polypeptides which bind to nucleic acids and may therefore be of predictive value in identifying karyophilic proteins.
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PMID:Prediction and demonstration of a novel Epstein-Barr virus nuclear antigen. 283 32

Two established cell lines of human B-cell lymphomas derived from Burkitt lymphomas and their Epstein-Barr virus-transformed counterparts were analyzed with respect to their ability to bind the beta-galactoside-specific lectin Ricinus communis agglutinin (RCA). Native and sialidase- as well as sialidase-beta-galactosidase-treated cells were compared. The method for the quantitative determination of average numbers of binding sites and of apparent affinity constants was flow cytometry with fluorescence-labeled lectin. Although with native cells there was no significant deviation of the values for virus-transformed cells from those for the parent cells, some differences could be detected after glycosidase treatment. The general procedure of the combined application of specific glycosidases and the quantitation of sugar-specific lectin binding is recommended as a general strategy for the differentiation of cells with known or putative differences in biological functions.
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PMID:A comparison of established human lymphoma lines by flow cytometry: quantitation of Ricinus communis agglutinin binding and the effect of specific glycosidases. 299 42

The BamHI Nhet fragment of the B958 strain of Epstein-Barr virus (EBV) encodes a membrane protein (BNLF-1) that is present in cells transformed by EBV. We made a hybrid protein in which a polypeptide sequence from the carboxyl-terminal part of BNLF-1 is fused to Escherichia coli beta-galactosidase. This hybrid protein was used to immunize rabbits, and the resulting antiserum was purified by immunoaffinity chromatography. The antiserum was able to immunoprecipitate BNLF-1 from cell lysates. We found that BNLF-1 is phosphorylated at serines in EBV genome-positive B-cell lines. Pulse-chase analyses with [35S]methionine indicated that BNLF-1 is turned over in lymphoblasts with a half-life of approximately 5 h. Protein immunoblots of EBV genome-positive B-cell lines revealed both a 62,000-molecular-mass band corresponding to BNLF-1 and a myriad of lower-molecular-mass bands. We postulate that these lower-molecular-mass bands are degradation products resulting from the turnover of BNLF-1 in cells. The BNLF-1 gene was expressed in COS cells, and the protein was both phosphorylated and turned over in these cells.
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PMID:Posttranslational processing of an Epstein-Barr virus-encoded membrane protein expressed in cells transformed by Epstein-Barr virus. 302 13

The nucleotide sequence of an Epstein-Barr virus gene expressed in latently infected growth-transformed cells is known to include a long open reading frame containing a 33-base-pair repeat element. A bacterial fusion protein constructed from a portion of the reading frame and Escherichia coli beta-galactosidase was used to produce sera in rabbits against the previously unidentified gene product. The viral protein detected with these sera in latently infected cells varies in size with the number of copies of the DNA repeat element. Translation of the RNA in vitro yields a protein of similar size. As expected from its primary sequence, the protein is a membrane protein. Immunofluorescence studies with the rabbit antisera suggest that the protein is in the plasma membrane. Thus, this protein could be the lymphocyte-determined membrane antigen (LYDMA) responsible for the generation of T-cell immunity to latently infected cells.
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PMID:A membrane protein encoded by Epstein-Barr virus in latent growth-transforming infection. 609 74

Assay conditions were studied for eight lysosomal enzymes in lymphoblastoid cell lines transformed by Epstein-Barr virus. The transformed lymphoblastoid cells retained all eight enzyme activities, though the levels sometimes differed from those in the peripheral lymphocytes or granulocytes. The levels of these eight lysosomal enzymes were measured in lymphoblastoid cells from 11 patients with hereditary lysosomal storage diseases--GMI-gangliosidosis, a variant of beta-galactosidase deficiency (sialidase deficiency with a partial beta-galactosidase deficiency), Tay-Sachs disease, Gaucher disease, Hurler syndrome, Scheie syndrome and I-cell disease--and from 20 of their obligate heterozygotes. No activity of enzymes that were deficient in the respective disease, except I-cell disease, was detected in the lymphoblastoid cells from the patient. In I-cell disease, the cells showed lower levels of some enzyme activities. beta-D-Galactosidase activity from heterozygotes of the patient with GMI-gangliosidosis and alpha-L-iduronidase activity from heterozygotes of the patient with Hurler syndrome were in carrier range. On sephadex G-150 gel filtration, beta-D-galactosidase in control material gave two peaks (I and II). In GMI-gangliosidosis, peak II was absent and peak I was markedly diminished. Peak II in the heterozygotes was smaller than that of control. On DEAE cellulose column chromatography of hexosaminidase, two major isoenzymes (hexosaminidase A and B) were detected in control. However, hexosaminidase A was not detected in Tay-Sachs disease, and the ratios of hexosaminidase (Hex) A/Hex B in the parents were lower than those in control.
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PMID:Lymphoblastoid cell lines, transformed by Epstein-Barr virus, in the enzymatic study of hereditary lysosomal storage diseases. 627 59

Epstein-Barr virus association in nonproducer human lymphoblastoid cell lines can be demonstrated by the presence of the virus genome (nucleic acid hybridization studies) or by the detection of the virus-coded complement-fixing antigen (complement fixation and/or anti-complement immunofluorescent test). This paper describes an enzyme immunoassay for the detection of Epstein-Barr virus complement-fixing antigen and its application to the demonstration of Epstein-Barr virus association in nonproducer lymphoblastoid cell lines. The assay is based on competition for complement between Epstein-Barr complement-fixing antigen and its specific antibody and a probe complex composed of Escherichia coli beta-galactosidase and specific anti-beta-galactosidase antibody. This competitive enzyme immunoassay is a specific and sensitive procedure for detecting Epstein-Barr virus association in nonproducer cell lines, allowing also quantitative estimation of the amount of antigen produced.
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PMID:New method for detecting Epstein-Barr virus association in nonproducer lymphoblastoid cell lines. 631 4

The present experiments were initiated to see if cells capable of binding antigens could make polyreactive antibodies. Fluorescein isothiocyanate-labeled self and non-self antigens were incubated with B cells from normal individuals. Antigen-binding cells were separated from non-antigen-binding cells by flow cytometry, immortalized with Epstein-Barr virus and analyzed at the clonal level for their capacity to make polyreactive antibodies. Four to six times more cells making polyreactive antibodies were found in the B cell subset that bound antigens than in the B cell subset that did not bind antigens. The majority of the polyreactive antibodies were of the immunoglobulin (Ig)M isotype. Immunoflow cytometry revealed that cell lines making polyreactive antibodies bound a variety of antigens (e.g., insulin, IgGFc and beta-galactosidase), whereas cell lines making monoreactive antibodies bound only a single antigen. The binding of antigens to B cell lines that made polyreactive antibodies could be inhibited (range, 28%-57%) by both homogeneous and heterogeneous antigens. Both CD5+ and CD5- antigen-binding B cells made polyreactive antibodies, but the frequency was slightly higher in the CD5+ antigen-binding (85%) as compared to the CD5- antigen-binding (50%) population. Comparison of CD5+ B cells that bound antigens with CD5+ B cells that did not bind antigens showed that approximately 86% of the former, but only 15% of the latter, made polyreactive antibodies. It is concluded that cells capable of binding a variety of different antigens can make polyreactive antibodies and that antigen binding is a good marker for identifying polyreactive antibody-producing cells.
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PMID:Antigen-binding B cells and polyreactive antibodies. 753 91


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