Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.27.5 (RNase)
 17,967 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The secondary and tertiary structures of the 35S RNA of Rous Sarcoma virus have been investigated. T1 RNase partial digests have been first resolved into their components by gel electrophoresis under non denaturing conditions and then each component analyzed further by various techniques. More than one hundred structured fragments have thus been isolated and shown to consist of several individual nucleotide sequences located far apart on the genome. On the basis of the results, a cloverleaf model for the structure of RSV 35S RNA is proposed that has implications for the various biological functions of this RNA.
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PMID:Analysis of the secondary and tertiary structures of Rous sarcoma virus RNA. 625 13

The src genes of different Rous sarcoma virus (RSV) strains have been reported to be highly conserved by some investigators using RNA-cDNA hybridization, whereas others using oligonucleotide, peptide, and serological analyses have judged src genes to be variable in 30 to 50% of the respective markers. Moreover, distinctive src oligonucleotides and peptides of so-called recovered RSVs (rRSV's) whose src genes were reported to be experimentally transduced from the cell are thought to represent specific markers of host-derived src sequences. By contrast, we have pointed out previously that these markers may represent point mutations of parental equivalents. Here we have compared the src-specific sequences of eight RSV strains and of two rRSV's to each other and to a molecular clone of the src-related chicken locus. Our comparisons are based on RNase T(1)-resistant oligonucleotides of RNA hybridized to src-specific cDNA, which was prepared by hybridizing RSV cDNA with RNA of isogenic src deletion mutants, or to a cloned cellular src-related DNA. All of the approximately 20 src-oligonucleotides of a given RSV strain were recovered by src-specific cDNA's of all other RSV strains or by cellular src-related DNA. The number of oligonucleotides varied slightly with the length of the src deletion used to prepare src-specific cDNA, thus providing a measure for src deletion mutants. Our data indicate that the src genes of all RSV strains tested, including the two reportedly transduced from the cell, are about 98% conserved and completely allelic with only scattered single nucleotide differences in certain variable regions which are subject to point mutations. Hence, based on the src oligonucleotide markers analyzed by us and others, we cannot distinguish between a cellular and viral origin of rRSV's. However, the following are not compatible with a cellular origin of rRSV's. (i) The only putative oligonucleotide marker which is exclusively shared by the two rRSV's studied and which differs from a parental counterpart in a single base was not detectable in cellular src-related DNA. (ii) The number of different allelic src markers observed by us and others in rRSV's was too large to derive from one or two known cellular src-related loci. (iii) The known absence of linkage of the cellular src-related locus with other virion sequences was extended to all non-src oligonucleotides, including some mapping directly adjacent to src. This is difficult to reconcile with the claim that transformation-defective, partial src deletion mutants of RSV which contain both, one, or, as we show here, possibly no src termini nevertheless transduce at the same frequencies, even though homologous, single or double illegitimate recombinations would be involved. Given (i) our evidence that src genes are subject to point mutation under selective conditions similar to those prevailing when rRSV's were generated and (ii) the lack of absolute evidence for the clonal purity of the transformation-defective, partial src deletion mutants of RSV used to generate rRSV's, we submit that the src genes of rRSV's could have been generated by cross-reactivation of nonoverlapping src deletions or mutation of src variants possibly present in transformation-defective, partial src deletion mutants of RSV. To prove experimental transduction, unambiguous markers need to be identified, or it would be necessary to generate rRSV's with molecularly cloned transformation-defective, partial src deletion mutants of RSV. Although our evidence casts doubt on the idea that specific src sequences of rRSV's originated by transduction, the close relationship between viral src and cellular src-related sequences argues that src genes originated at one time in evolution from the cell by events that involved illegitimate recombination and deletion of non-src sequences that interrupt the cellular src locus.
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PMID:src Genes of ten Rous sarcoma virus strains, including two reportedly transduced from the cell, are completely allelic; putative markers of transduction are not detected. 627 Mar 50

We have recently shown that a newly isolated avian sarcoma virus, UR2, is defective in replication and contains no sequences homologous to the src gene of Rous sarcoma virus. In this study, we analyzed the genetic structure and transforming sequence of UR2 by oligonucleotide fingerprinting. The sizes of the genomic RNAs of UR2 and its associated helper virus, UR2AV, were determined to be 24S and 35S, respectively, by sucrose gradient sedimentation. The molecular weight of the 24S UR2 genomic RNA was estimated to be 1.1 x 10(6), corresponding to 3,300 nucleotides, by gel electrophoresis under the native and denatured conditions. RNase T1 oligonucleotide mapping indicated that UR2 RNA contains seven unique oligonucleotides in the middle of the genome and shares eight 5'- and six 3'-terminal oligonucleotides with UR2AV RNA. From these data, we estimated that UR2 RNA contains a unique sequence of about 12 kilobases in the middle of the genome, and contains 1.4 and 0.7 kilobases of sequences shared with UR2AV RNA at the 5' and 3' ends, respectively. Partial sequence analysis of the UR2-specific oligonucleotides by RNase A digestion revealed that there are no homologous counterparts to these oligonucleotides in the RNAs of other avian sarcoma and acute leukemia viruses studied to date. UR2-transformed non-virus-producing cells contain a single 24S viral RNA which is most likely the message coding for the transforming protein of UR2. On the basis of the uniqueness of the transforming sequence, we concluded that UR2 is a new member of the defective avian sarcoma viruses.
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PMID:Genetic structure and transforming sequence of avian sarcoma virus UR2. 628 74

We have used the method of chemical crosslinking in order to determine the spatial interactions between components of Rous sarcoma virus. A high molecular weight complex formed by crosslinking has been isolated by ultracentrifugation on sucrose density gradients containing 0.1% (w/v) sodium dodecyl sulphate. This complex is composed of the two viral glycoproteins gp85 and gp35, the gag protein p19, and the viral RNA. Two types of bonding are important for the formation and stability of the complex: first, native disulphide bonds between gp85 and gp35 and between individual p19 molecules; and second, hetero-crosslinking between gp35 and p19 as well as homo-crosslinking between p19. Although viral RNA is quantitatively present in the complex, experiments with RNase treatment show that it is not essential for its formation or stability. A small amount of lipid is present in the complex and appears to be crosslinked to p19. In vitro-labelling of purified virus with the lipophilic photoactivatable reagent [125I] iodonaphthylazide resulted in the labelling of gp35 and p19/23. In vivo-labelling of virus with [3H]palmitate resulted in only gp35 becoming labelled. These results substantiate the membrane association of these proteins. The significance of the interactions in the high molecular weight complex for the stability of the virus and, by implication, the role which they may play in viral assembly are discussed.
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PMID:Rous sarcoma virus p19 and gp35 can be chemically crosslinked to high molecular weight complexes. An insight into virus assembly. 632 11

We have re-examined whether pp60c-src, the normal cellular homologue of the transforming protein of Rous sarcoma virus, is present in human T cells. By in vitro immune-complex kinase assay or Western blotting with the anti-pp60c-src mAbs 327 or GD11, pp60c-src was found to be present in lysates of T cell lines, including the Jurkat T cell line. The 327 and GD11 mAbs have been reported to be specific for pp60c-src and not to cross-react with other src family members or other kinases. Furthermore, the size of the pp60c-src bands present on Western blotting and in vitro kinase assay were clearly different from those of p56lck or p59fyn. In addition, pp60c-src is detected in the HTLV-I-derived T cell lines S1T and C8, which lack expression of p56lck and p59fyn. RNase protection assays confirmed that pp60c-src mRNA is present in Jurkat T cells. We also found pp60c-src protein to be constitutively present in freshly isolated thymocytes. In contrast, pp60c-src was absent, or present at extremely low levels, in normal, resting peripheral blood T lymphocytes, which is in agreement with previous findings. However, after stimulation of resting T cells with the mitogenic lectin PHA or with Ab to the TCR complex, pp60c-src expression is induced in both CD4+ and CD8+ T cell subsets, with peak expression detectable 12 to 24 h after T cell activation. The levels of pp60c-src are low in all T cells except Jurkat, where levels of pp60c-src are comparable to levels found in a glioblastoma cell line (T98G). Nevertheless, significant levels of pp60c-src kinase activity are readily detectable in thymocytes and activated normal T cells as well as in T cell lines. The finding that pp60c-src is inducible following activation through the TCR suggests that pp60c-src may play a specific role in the normal T cell activation pathway.
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PMID:pp60c-src expression is induced by activation of normal human T lymphocytes. 753 11

The internal structural proteins of retroviruses are proteolytically processed from the Gag polyprotein, which alone is able to assemble into virus-like particles when expressed in cells. All Gag proteins contain domains corresponding to the three structural proteins MA, CA, and NC. We have expressed the CA and NC domains together as a unit in Escherichia coli, both for Rous sarcoma virus (RSV) and for human immunodeficiency virus type 1 (HIV-1). We also expressed a similar HIV-1 protein carrying the C-terminal p6 domain. RSV CA-NC, HIV-1 CA-NC, and HIV-1 CA-NC-p6 were purified in native form by classic methods. After adjustment of the pH and salt concentration, each of these proteins was found to assemble at a low level of efficiency into structures that resembled circular sheets and roughly spherical particles. The presence of RNA dramatically increased the efficiency of assembly, and in this case all three proteins formed hollow, cylindrical particles whose lengths were determined by the size of the RNA. The optimal pH at which assembly occurred was 5.5 for the RSV protein and 8.0 for the HIV-1 proteins. The treatment of the RSV CA-NC cylindrical particles with nonionic detergent, with ribonuclease, or with viral protease caused disassembly. These results suggest that RNA plays an important structural role in the virion and that it may initiate and organize the assembly process. The in vitro system described should facilitate the dissection of assembly pathways in retroviruses.
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PMID:Self-assembly in vitro of purified CA-NC proteins from Rous sarcoma virus and human immunodeficiency virus type 1. 766 50

Different portions of the 5'-upstream region of the mouse proliferating cell-nuclear-antigen (PCNA) gene were combined with the bacterial chloramphenicol acetyltransferase (CAT) gene of a CAT vector. A transient expression assay of CAT activity in mouse neuroblastoma N18TG2 cells transfected with these recombinant plasmids and RNase protection analysis have revealed the existence of a negative regulatory region between nucleotides -1231 and -624 (+1 denotes the transcription initiation site). The CAT expression levels were gradually increased, depending on the extent of deletion from the 5'-terminus in this region, suggesting that the negative regulatory region consists of multiple elements with rather weak repressing activities. Significant sequence similarity was found between the negative regulatory region of the PCNA gene and those of the several reported genes. A 752-bp segment containing this negative regulatory region repressed the function of the PCNA gene promoter in an orientation-independent and position-independent manner. However, the negative regulatory region showed almost no repressing effect on the functions of the heterologous gene promoters such as the simian virus 40 enhancer promoter, the enhancer promoter in the Rous sarcoma virus long-terminal repeat and the mouse DNA polymerase beta gene promoter. These results suggest that the negative regulatory region of the mouse PCNA gene functions specifically to its own promoter. This unique property is discussed in comparison with that of the negative regulatory elements of the mouse DNA polymerase beta gene.
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PMID:Nucleotide sequence and promoter-specific effect of a negative regulatory region located upstream of the mouse proliferating cell nuclear antigen gene. 790 77

We have isolated a complementary DNA (cDNA) clone, termed N14, from a cDNA library derived from normal rat fibroblast 3Y1 cells using a differential screening procedure. N14 cDNA was 1115 nucleotides in length and contained an open reading frame of 172 amino acid residues. The expression of N14 gene was significantly increased in Rous sarcoma virus-transformed 3Y1 cells (SR-3Y1) compared with that in parental 3Y1 cells. The high level of N14 gene expression was reduced by treatment with herbimycin A, indicating that the expression was dependent upon the activity of pp60v-src tyrosine kinase. A homology search revealed that the nucleotide sequence of N14 cDNA was nearly identical to that of the rat nonsarcomeric myosin regulatory light chain cDNA (RLC-B), with the exception of a 250-nucleotide insertion which is present between C at position +483 and G at position +484 in the RLC-B cDNA. Southern blot analysis indicated that N14 gene was present as a single copy in the rat genome. Therefore, these two mRNAs might be generated through the alternative splicing mechanism. However, a RNase protection assay revealed that RLC-B mRNA was not expressed in SR-3Y1 cells. In addition, the amount of N14 mRNA was also increased in other types of transformed cells, including v-mos-, simian virus 40-, and v-Ha-ras-transformed 3Y1 cells.
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PMID:Molecular cloning of a unique complementary DNA of rat myosin regulatory light chain and its elevated expression in v-src-transformed rat culture cell lines. 829 99

RNA and ribonuclease-resistant RNA analogs that bound and neutralized Rous sarcoma virus (RSV) were isolated from a large pool of random sequences by multiple cycles of in vitro selection using infectious viral particles. The selected RNA pool of RSV-binding sequences at a concentration of 0.16 microM completely neutralized the virus. Of 19 sequences cloned from the selected pool, 5 inhibited RSV infection. The selected RNA and RNA analogs were shown to neutralize RSV by interacting with the virus, rather than by adversely affecting the host cells. The selection of the anti-RSV RNA and RNA analogs by intact virions immediately suggests the potential application of this approach to develop RNA and RNA analogs as inhibitors of other viruses such as human immunodeficiency virus.
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PMID:Isolation of virus-neutralizing RNAs from a large pool of random sequences. 852 93

The antiproliferative action of the guanine-specific ribonuclease secreted by Bacillus intermedius (binase) was studied in different chicken and mouse cell lines. The proliferation rate of chicken embryo fibroblasts, either normal or Rous sarcoma virus-transformed, was significantly reduced by binase treatment. Among mouse fibroblasts, v-ras-transformed NIH3T3 cells were sensitive to binase, whereas the growth of non-transformed, v-src-transformed or v-fms-transformed NIH3T3 cells was not affected. A 48 h treatment with binase inhibited the Ca2+-dependent K+ current of v-ras-transformed NIH3T3 cells but had no effect on this membrane current in non-transformed and in v-src- or v-fms-transformed NIH3T3 cells. Our results suggest that mammalian cells expressing the ras-oncogene are a potential target for the antiproliferative action of binase.
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PMID:Bacillus intermedius ribonuclease as inhibitor of cell proliferation and membrane current. 1116 12


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