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:3.1.27.1 (RNase)
16,360 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Low ionic strength (50 to 100 mM NaCl) and pH 6.0 were found to be optimal conditions for in vitro conversion of Epstein-Barr virus (EBV)-determined nuclear antigen (EBNA)-negative nuclei to EBNA-positive nuclei by addition of the complement-fixing (CF) antigen extracted from Raji cells. In vitro conversion of nuclei to EBNA-positively was sensitive to DNase but not to RNase treatment. This suggests that nuclear DNA is a specific target substance to which EBV-CF antigen binds. If nuclei were fixed with methanol/acetic acid and subsequently treated with 0.6 M NaCl, EBNA could be eluted from in vitro-converted Ramos nuclei with 0.3 and 0.4 M NaCl. The same conditions were also found to be optimal for the adsorption and elution of EBV-CF antigen in DNA-cellulose chromatography. This indicates that the DNA-binding properties of EBNA antigen can be studied by "chromatography" on fixed nuclei followed by the ACIF test. The obvious advantages of this method over chromatography on DNA-cellulose are its simplicity, the possibility of testing many samples in one experiment and, especially, the use of minimal amounts of material. Significant differences in elution patterns for EBNA were found when nuclei derived from different cell lines (Ramos, Raji, and P3HR-1) were converted in vitro to EBNA-positivity. EBNA is eluted from in vitro-converted nuclei of EBV genome-positive P3HR-1 cells at an almost 0.1 M higher concentration of NaCl than is necesssary for a similar degree of elution from nuclei of EBV genome-negative Ramos cells.
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PMID:Study of Epstein-Barr virus-determined nuclear antigen (EBNA) by chromatography on fixed cell nuclei. 8 40

Primary human amnion cell monolayers which had been treated with DEAE-dextran, washed, and then inoculated with sonicated cells of the EB3 line of Burkitt's lymphoma cells developed foci of transformed amnion cells 7 to 14 days later. When either the DEAE-dextran or the sonicate was omitted, no significant transformation was found. The foci consisted of enlarging mounds of rapidly dividing cells, which upon subculturing continued their high miotic activity; and strains or lines of the transformed amnion cells were thus readily established. The modal number of chromosomes in such lines was 65 instead of the normal 46. Not all human amnions yielded cells transformable by EB3 cell sonicate, as determined by direct comparisions using the same cultural conditions and testing with the same fresh sonicate preparation in the same experiment. Overall, it appeared that only about 40 to 50% of the amnions yielded transformable cell monolayers; the rest gave monolayers apprently completely refractory to the transformation. The transformed amnion cells contained nuclear and cytoplasmic Epstein-Barr virus (EBV) antigen(s), as revealed by indirect immunofluorescence tests. EB3 cell sonicate also caused the appearance of rapidly growing transformed cell foci on secondary rat embryo cell monolayers which had been sensitized with DEAE-dextran. Calcium in the cell maintenance medium decreased the number of transformed foci found, both on the human and on the rat cell monlayers. Sonicates of cultured normal human leucocytes had no such transforming activity for either the human or the rat cells. The transforming agent in EB3 cell sonicate was completely destructible by either deoxyribonuclease or trypsin, but not by ribonuclease, and was not neutralizable by anti-EBV serum. The simplest interpretation of these results is that the transforming agent is part of all of the EBV DNA plus some necessary protein, with both the DNA and the protein accessible to hydrolytic enzyme action.
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PMID:Use of a transfection method to demonstrate a monolayer cell transforming agent from the EB3 line of Burkitt's lymphoma cells. 18 Feb 48

The Epstein-Barr virus (EBV)-associated nuclear antigen (EBNA) was purified 85-fold from a nuclear pellet derived from an EBV-transformed B lyphoblastoid cell line by a five-step procedure consisting of preparation of extract, heating at 80 degrees C in phosphate buffer, ammonium sulfate precipitation, preparative ultracentrifugation, and affinity chromatography on double-stranded DNA-cellulose. The purified complement fixing antigen specifically blocked the anticomplement immunofluorescence assay for EBNA. Several properties indicate a close association of EBNA with chromatin, viz. 1) precipitation of antigenic activity by phosphate buffer and subsequent thermal fractionation; 2) partial sensitivity of antigenic activity to DNase (but not to RNase) and restoration of activity by addition of calf thymus DNA; and 3) specific binding of EBNA to double-stranded DNA-cellulose. Other properties of EBNA, including its unusual heat stability, are described.
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PMID:Partial purification and properties of the Epstein-Barr virus-associated nuclear antigen. 20 60

Several virion and nonvirion DNAs were tested for the ability to activate endogenous type C virus in BALB/c-derived mouse cells using the calcium precipitation technique. The DNAs from all herpesviruses tested activated xenotropic type C virus synthesis. These included DNAs from herpes simplex virus types 1 and 2, Epstein-Barr virus, human cytomegalovirus, SA8 virus, infectious bovine rhinotracheitis virus, pseudorabies virus, and herpes saimiri virus (M-DNA). In contrast, DNAs from vaccinia virus, simian virus 40, primate cells, bacteria, mycoplasma, and salmon sperm showed no ability to activate type C virus when tested under the same conditions. Several herpesviruses and vaccinia virus, which were highly infectious for the BALB/c cells used, were tested for their ability to activate type C virus after UV irradiation. All herpesviruses tested were positive, while vaccinia virus was negative. Unirradiated simian virus 40 also showed no ability to activate type C virus. Activation of type C virus by DNA from herpes simplex virus was observed after shearing or sonication of the DNA to an average size of 3 x 10(6) daltons, but was not observed with DNA sonicated to an average size of 1 x 10(6) daltons. Alkali denaturation of DNA from herpes simplex virus or treatment with DNase, but not RNase, destroyed its ability to activate type C virus, as did crosslinking of the DNA with 4,5',8-trimethylpsoralen (psoralen) and light.
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PMID:Activation of endogenous type C virus in BALB/c mouse cells by herpesvirus DNA. 21 61

The modulation of nuclear antigen expression from the Epstein-Barr virus (EBV) genome in virus-infected cells is crucial to the establishment and maintenance of the immortalized state. The EBV nuclear antigen (EBNA) genes are all transcribed from either of two promoters whose alternate usage is not understood. We have studied the EBNA transcriptional domain by using various promoter constructs to transfect a variety of EBV positive cell lines and then measured promoter activity by RNase protection analysis and nuclear run-on transcription assay. These experiments have shown that at least two distinct and novel DNA sequence elements are located in the intronic region situated between both promoters and that their presence results in a 100-fold stimulation of transcription initiated from the upstream promoter. One of these elements is shown to bind nuclear proteins from an EBV-positive cell line. In addition, an important sequence homology is noted between this element and the core sequences of a number of well known viral enhancers. Taken together, the results show that EBNA transcription is controlled by upstream and intronic elements in a regulatory domain that is at least 7 kb long.
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PMID:Novel downstream elements upregulate transcription initiated from an Epstein-Barr virus latent promoter. 184 96

We have reported previously the detection of two stable immediate-early (IE) transcripts that accumulate in cycloheximide-treated cells infected with herpesvirus saimiri (HVS). These are the 1.6-kb mRNA from the 52-kDa gene (which is homologous to the BSLF2-BMLF1 gene of Epstein-Barr virus) and the 1.3-kb mRNA from the HindIII-G fragment of virus DNA. In order to study the roles of the HVS IE gene products in the progression of a lytic infection, the promoter region of the delayed-early 110-kDa gene of HVS was sequenced, the transcription initiation site was mapped by RNase protection, and the promoter sequences were cloned upstream of the chloramphenicol acetyltransferase (CAT) gene. Sequences between -447 and +37 (relative to the 110-kDa transcription initiation site) were sufficient for response to HVS superinfection of transfected cells, but the 110-kDa promoter was activated only poorly by the 52-kDa and HindIII-G IE (IE-G) proteins in cotransfection experiments. However, a distinct region of the genome, EcoRI-D (15 kbp), was able to activate 110-kDa-CAT expression relatively efficiently in similar experiments. A 4.7-kbp PstI fragment encoding this function was isolated and sequenced, and further subcloning identified the gene encoding the EcoRI-D trans activator. This gene, which we now designate HVS.R, is homologous to the BRLF1-encoded transcriptional effector of Epstein-Barr virus.
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PMID:Regulation of the herpesvirus saimiri (HVS) delayed-early 110-kilodalton promoter by HVS immediate-early gene products and a homolog of the Epstein-Barr virus R trans activator. 185 23

Recombinant plasmids containing sequences from the BamHI-E rightward reading frames 2a and 2b (BERF2a and 2b) of the Epstein-Barr virus (EBV) genome were isolated from a library of cDNA clones which had been previously made from the EBV B95-8 lymphoblastoid cell line (M. Bodescot, O. Brison, and M. Perricaudet, Nucleic Acids Res. 14:7103-7114, 1986). The characterization of these clones in combination with RNase mapping experiments led to the identification of one leftward and several rightward transcripts traversing the EBV-determined nuclear antigen EBNA3B coding region. One cDNA (T7) contains a continuous open reading frame generated by the splicing together of BERF2a and BERF2b. The T7 clone was used to reconstruct a complete fused BERF2a/2b open reading frame in an adenovirus-based expression vector. Western immunoblotting and immunofluorescence experiments using human 293 cells showed that the recombinant plasmid is capable of expressing a protein with a size, immunological characteristics, and a subcellular localization indistinguishable from those of native B95-8 EBNA3B.
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PMID:cDNA cloning and transient expression of the Epstein-Barr virus-determined nuclear antigen EBNA3B in human cells and identification of novel transcripts from its coding region. 215 61

Dialyzable low molecular weight antibody-augmenting factors (LMAAF) were found in the culture supernatant of human tonsillar lymphocytes which were not stimulated by antigen and/or mitogen in vitro. Phagocyte-depleted nylon wool-adherent lymphocytes (M-Ny+ cells) were responsible for the release of the LMAAF. Marbrook's culture system was adopted to assay for the LMAAF. The M-Ny+ cells, which were cultured without antigen and/or without mitogen in the reservoir of Marbrook's diffusion culture vessel, released the LMAAF, which diffused across a dialysis membrane and significantly augmented the pokeweed mitogen (PWM)-induced plaque-forming cell (PFC) response of phagocyte-depleted lymphocytes (M-cells) cultured in the inner vessel. Phagocyte-depleted nylon wool-passed lymphocytes (M-Ny- cells) cultured in the reservoir could not augment the PWM-induced PFC response of the M- cells cultured in the inner vessel. The exuded fluid, which was the dialysate of the culture supernatant of the M-Ny+ cells ultrafiltrated with dialysis tubing, also enhanced the PFC response of M- cells cultured in 24-well multi plates. The exuded fluid also augmented the total IgM and IgG production of human tonsillar and peripheral blood lymphocytes measured by enzyme-linked immunosorbent assay (ELISA) systems. Gel filtration chromatography on Sephadex G-25 Superfine column showed that the LMAAF activity was demonstrated in the fractions corresponding to a molecular weight (m.w.) of 362 to 1,355 and a m.w. of 3,560 to 5,700, with a peak activity at about 4,500 dalton. The LMAAF were inactivated by treatment with proteinase K, but not by trypsin, alpha-chymotrypsin, RNase, and DNase, and were stable when treated at 56 C for 60 min. The dialysates of culture supernatants from two out of seven Epstein-Barr virus (EBV)-transformed M-Ny+ cell lines showed LMAAF-like activity. These results indicate that phagocyte-depleted nylon wool-adherent lymphocytes, possibly B cells, release low molecular weight factors displaying augmenting activity for human antibody production in vitro.
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PMID:Low molecular weight factors displaying augmenting activity for human antibody production in vitro. 283 11

An inhibitory factor, which has been shown to suppress the uptake of 125I-iododeoxyuridine by both lymphoid and nonlymphoid cells, was isolated from the supernatant of an Epstein-Barr virus- (EBV) transformed B cell line (1605L) established from a cotton-topped marmoset. Purification of the inhibitor, which was produced in serum-free medium by crowded cultures of the 1605L cells, was achieved by DEAE-cellulose chromatography followed by preparative polyacrylamide gel electrophoresis. The apparent m.w. of the 1605L factor was determined to be 65,000 to 70,000 by SDS-polyacrylamide gel electrophoresis. The inhibitor was sensitive to digestion by trypsin and chymotrypsin but not RNase or DNase, indicating that it was protein in nature. Exposure of the 1605L factor to 56 degrees C for 1/2 hr or pH 2 for 48 hr at 4 degrees C destroyed its inhibitory activity. The biochemical characteristics and activity of the 1605L inhibitor distinguish it from Type I interferon and several other soluble immunologic mediators known to be produced by lymphoid cell lines.
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PMID:Purification and biochemical characterization of an inhibitor of DNA synthesis produced by an Epstein-Barr virus-transformed B cell line. 624 72

With the improved rapid sequencing techniques, the earlier sequence of U2 RNA of Novikoff hepatoma (Shibata et al, J. Biol. Chem. 250, 3909-3920, 1975) was reanalyzed and modified. The improved sequence of U2 RNA is 188 (or 189) nucleotides long and is in register with a characterized U2 RNA pseudogene (Denison et al, PNAS 78, 810-814, 1981) except for an 11 nucleotide sequence (nucleotides 147-157) which is absent from the pseudogene. From these results, a secondary structure of U2 RNA is proposed which is supported by the preferred cleavage sites with T1-RNase, RNase A and S1 nuclease. Isolated U2 RNA was cleaved by T1-RNase preferentially at positions 64 and 164, whereas U2 RNA in U2-snRNP was cleaved only at position 64, indicating that position 164 is protected in U2-snRNP. As with U1 RNA (Epstein et al, PNAS 78, 1562-1566, 1981) the 5'-end of isolated U2 RNA was not preferentially cleaved by T1-RNase.
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PMID:Primary and secondary structure of U2 snRNA. 679 40


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