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)

Immunohistochemical studies with antiserum against the protamines of the toad, Bufo japonicus, revealed that the sperm nucleus loses protamines within 5 min after entry into the egg. Likewise, lysolecithin-permeabilized sperm incubated with the egg extract lose the protamines within 1 min, accompanied by nuclear decondensation. The activities that induce both protamine removal and decondensation in sperm nuclei were found in extracts from growing and mature oocytes and pregastrula embryos, but not in postneurula embryos or adult tissues. SDS-PAGE analyses revealed that the egg extract removed not only protamines from the Bufo sperm, but also selectively the sperm-specific basic proteins from sperm nuclei of Xenopus laevis. The protamine-removing activity (PRA) was partially purified from egg extracts as negatively charged macromolecules by anion-exchange chromatography and gel filtration. The PRA was heat-stable (100 degrees C, 10 min) and sensitive to proteinase K, but not to RNase A and DNase I. Immunoblot analysis of the supernatant after incubation of Bufo sperm in the fraction with the PRA revealed that protamines derived from sperm nuclei were associated with a major protein of the fraction. This protein exhibited mobilities of 140 and 36 kDa on native- and SDS-PAGE, respectively, with the isoelectric points in the range 4.2 to 4.5 and possessed an amino acid composition quite similar to that reported for Xenopus nucleoplasmin. We propose that in fertilized eggs the protamines are removed from sperm nuclei by nucleoplasmin by binding to but not by enzymatic degradation of the protamine.
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PMID:Characterization of the ooplasmic factor inducing decondensation of and protamine removal from toad sperm nuclei: involvement of nucleoplasmin. 193 66

In order to establish the presence of Z-DNA sequences in the normal crystalline lens and to define their structure-function relationship, fixed and unfixed calf lens tissue sections were examined immunohistochemically. Polyclonal and monoclonal anti-Z-DNA antibodies were developed as immunoprobes, using brominated (Br-) poly(dG-dC).poly(dG-dC) as an antigen. The structure of the Z-helix antigen was confirmed by circular dichroism (CD) and U.V. spectroscopy. Whole rabbit and goat anti-Z-DNA sera; rabbit and goat IgG polyclonal anti-Z-DNA antibodies; and anti-Z-DNA monoclonal IgG antibodies were utilized as Z-DNA immunoprobes to localize the Z-DNA in calf lens tissue sections. Immunohistochemical examination using the peroxidase-antiperoxidase (PAP) method indicated that the cortex region of the lens reacted strongly with the anti-Z-DNA antibodies, while no immunoreaction could be observed in the nucleus region. Similar immunoreactive patterns were obtained whether whole sera, affinity purified IgG polyclonal antibodies or monoclonal antibodies were utilized. Immunobinding of anti-Z-DNA antibodies was low, effectively background type binding, in unfixed lens tissue sections. Various fixatives were tested to explore the potential antibody-Z-DNA interaction in calf lens tissue. Nuclear fixatives enhanced Z-DNA antibody immunoreactivity, while formalin, microanatomic and cytoplasmic fixatives produced lesser results. Digestion of the lens tissue with DNase I eliminated Z-DNA immunoreactivity, while RNase A and RNase T1 treatment had no effect. Actinomycin D also prevented Z-DNA immunoreactivity.
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PMID:Fixation and immunolocalization of left-handed Z-DNA sequences in the calf lens. 195 42

The carbamoylphosphate synthetase-aspartate transcarbamylase-dihydroorotase (CAD) gene encodes a tri-functional protein catalyzing the first three steps in de novo pyrimidine biosynthesis. Studies correlating CAD gene expression with cellular proliferation indicate the importance of understanding the regulation of the CAD gene. As a first step, the structure of the promoter region of the Syrian hamster CAD gene has been determined. Sequence analysis of 1671 base pairs of DNA revealed that the CAD promoter region is very GC rich. Primer extension analysis indicated that the transcription initiation site of the CAD gene is downstream from two GC boxes (consensus binding sites for the transcription factor Sp1). There is no TATA box appropriately spaced upstream from the transcription initiation site. Using RNase protection mapping, S1 nuclease analysis, and comparison to consensus splice donor/acceptor sites, the 5' end of the CAD gene has been determined to consist of a 241-base pair first exon, a 187-base pair first intron, a 140-base pair second exon, and a second intron that extends at least three kilobase pairs. Using conditions optimized for this GC-rich promoter, accurate transcription can be achieved in vitro. Analysis of CAD promoter deletions indicated that sequences extending only 114 base pairs upstream and 225 base pairs downstream from the transcription initiation site are sufficient for accurate and efficient transcription in vitro. DNase I footprinting reactions using this promoter fragment have identified three regions that bind proteins in a HeLa nuclear extract.
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PMID:Characterization of the 5' end of the growth-regulated Syrian hamster CAD gene. 198 61

The 5' flanking region of the mouse N-ras gene was investigated to determine the elements governing transcriptional activity of the gene. The promoter did not contain typical TATA or CCAAT boxes, and according to primer extension and RNase protection analyses, transcription started at several sites. These assays also confirmed the short nucleotide distance interposed between the N-ras transcription unit and the previously described upstream unr gene. Chromatin studies performed by digestion of nuclei with DNase I revealed the presence of four hypersensitive sites: a, b, c, and d. Deletion mutagenesis of the 5' flanking region revealed sequences responsible for both promotion and inhibition of transcription. These sequences resided within 230 bp upstream of the transcription initiation site. Hypersensitive site b colocalized with the 76-bp segment with promoter activity. The negative regulatory element at position -180 colocalized with hypersensitive site a, was active on the N-ras promoter in stable as well as transient assays, and down-regulated the heterologous herpes simplex virus thymidine kinase promoter. Footprint analysis and in vivo transfection-competition experiments indicated that a trans-acting factor is responsible for the negative effect on transcription. The interaction between the cis-acting negative regulatory element and the promoter region may play a role in the tissue- and developmental-stage-specific patterns of expression of the N-ras gene.
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PMID:Dissection of the mouse N-ras gene upstream regulatory sequences and identification of the promoter and a negative regulatory element. 199 95

We have partially purified a nuclear protein (PPT) from Physarum polycephalum that binds to the extrachromosomal ribosomal DNA telomeres of this acellular slime mold. Binding is specific for the (T2AG3)n telomere repeats, as evidenced by nitrocellulose filter binding assays, by gel mobility shift assays with both DNA fragments and double-stranded oligonucleotides, and by DNase I footprinting. PPT is remarkably heat stable, showing undiminished binding activity after incubation at 90 degrees C. It sediments at 1.2S, corresponding to a molecular weight of about 10,000 (for a globular protein), and its binding activity is undiminished by incubation with RNase, suggesting that it is not a ribonucleoprotein. We hypothesize that PPT plays a structural role in telomeres, perhaps preventing nucleolytic degradation or promoting telomere extension by a telomere-specific terminal transferase.
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PMID:Characterization of a telomere-binding protein from Physarum polycephalum. 200 10

Polyacrylamide gel electrophoresis of nucleic acids extracted from porcine faecal samples revealed in several samples the presence of two discrete bands. The bands were resistant to digestion with of DNase I and RNase T1, but not with RNase A in low salt conditions, indicating that they consisted of double stranded (ds) RNA. The two bands from different samples varied in sizes, in a range between 2.4-2.6 kbp and 1.7-1.9 kbp for the slow and fast moving band respectively. The bands cosedimented in CsCl gradients at an average density of 1.415 g/ml with icosahedral virus particles of a diameter of 34 nm and a triangulation number equal to 3. Aggregates of virus, which appeared to be immunocomplexes, were seen in one sample. From 244 faecal samples collected in one farm, 27 (11.1%) were found to contain the characteristic dsRNA pattern, with a higher prevalence in samples from animals 15 to 35 days old. The agent was equally distributed among samples from diarrhoeic or non-diarrhoeic animals. These results confirm the circulation among pigs of a novel virus, possibly of vertebrates, with a bisegmented double stranded RNA genome, similar to viruses previously described in humans, wild rats, guinea pigs, pigs, and chickens, for which the name "picobirnavirus" has been proposed.
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PMID:Identification in porcine faeces of a novel virus with a bisegmented double stranded RNA genome. 200 3

Babesia bovis is an intraerythrocytic protozoan that causes bovine babesiosis. Agarose gel electrophoresis of nucleic acids extracted from two isolates of B. bovis reveals, besides bulk DNA, an ethidium bromide-stainable band at about 5.5 kb. Further characterization of the latter with DNase I, RNase and mung bean nuclease suggested it to be a double-stranded RNA. Sonicated parasites were fractionated in a CsCl buoyant density gradient. A sample containing the 5.5-kb RNA was analysed under an electron microscope and a virus-like particle was observed.
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PMID:A putative RNA virus in Babesia bovis. 205 34

The intranuclear localization of the Ki-67 reactive antigen was immunocytochemically investigated using flow cytometry. HeLa S3 cells were immunocytochemically stained with the monoclonal antibody, Ki-67, after in situ treatments with various kinds of compounds, namely: HCl; NaCl; RNase; S1 nuclease and DNase I. The only treatment that markedly diminished the immunofluorescence intensity of the cells was exposure to DNase I. Nuclear fluorescence was no longer observed in the cells digested with relatively high concentrations of DNase I. These results suggest that the antigen recognized by Ki-67 is closely associated with DNA, but is not directly associated with either the nuclear matrix or histones.
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PMID:Intranuclear localization of the Ki-67 reactive antigen in HeLa cells. Flow cytometric analysis. 219 67

In the sea urchin embryo, late histone genes are transcribed at low levels during cleavage and blastula formation and at substantially higher levels in later stages of embryogenesis. To investigate the molecular basis of the stage-specific expression of a late H2B histone gene, we injected mutant genes lacking portions of 5'- and 3'-flanking regions into Lytechinus pictus embryos and monitored their expression by RNase protection. A 200-bp region located 489 bp downstream of the mRNA 3' terminus was necessary for the increase in transcription of the late H2B gene at the mid-blastula stage of development. DNase I and methylation interference footprint analyses located only one factor-binding site in this region, and gel mobility shift experiments showed that the DNA-binding activity of this factor (designated H2B abp 1) paralleled the transcriptional activity of the L1 H2B gene. Additional mutagenesis and microinjection experiments located the activator element to a 32-bp DNA segment that includes the H2B abp 1-binding site. These experiments also showed that the 32-bp fragment functions independently of position and orientation and therefore has the hallmarks of an enhancer. That this fragment contains most or all of the L1 H2B gene transcription-stimulatory activity makes it unusual among enhancerlike elements, which generally consist of several clustered factor-binding sites that act additively or cooperatively to affect transcription. The nucleotide sequence of the L1 H2B enhancer element suggests that the trans-acting factor that interacts with it is a member of the antennapedia or engrailed class of homeodomain proteins.
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PMID:Activation of a late H2B histone gene in blastula-stage sea urchin embryos by an unusual enhancer element located 3' of the gene. 224 80

Monoclonal antibody 5E5 labeled the nuclear antigen of the neurons in the guinea pig and rat central nervous systems including the cerebrum, cerebellum, spinal cord and retina. This antibody could discriminate neurons even among the same cell class. In in vitro study, only 10% of dividing PC12 cells was labeled with this antibody. An electron microscopic immunohistochemical study also revealed that this antibody selectively labeled heterochromatins in the neurons. Although we could not obtain any positive result by an immunoblot study, the antigenicity was remarkably diminished by the DNase I or S1 nuclease treatment on the tissue sections whereas RNase and trypsin was ineffective. These results suggested that this antigen might be a single-stranded DNA-protein complex resistant to proteolytic procedures, and possibly related to cell function or state of differentiation.
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PMID:A monoclonal antibody 5E5 recognizes an intranuclear antigen selectively present in a subpopulation of the neurons. 230 33


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