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:3.1.27.5 (RNase)
17,967 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The binding sites for influenza viral RNA polymerase on genome RNA segments were investigated. Ribonucleoprotein (RNP) cores containing the RNA polymerase were isolated from detergent-treated virions by glycerol gradient centrifugation. On ApG-primed in vitro transcription by the isolated RNP cores, different levels of RNA transcripts were synthesized for the eight RNP cores, suggesting an uneven distribution of the RNA polymerase. 3'-Terminal labeling of the RNP cores with the use of [32P]pCp and T4-RNA ligase indicated a reciprocal correlation between the levels of the RNA-3' label and RNA synthesis. Centrifugation of detergent-treated virions in a double gradient of cesium trifluoroacetate (or cesium chloride) and glycerol yielded RNA polymerase-RNA complexes devoid of NP, the major RNA-bound protein, but the pattern of RNA-3' labeling remained virtually unaffected. All these observations together indicated that the RNA polymerase is associated near the 3' termini of some viral RNA segments, thereby preventing the in vitro labeling of the RNA-3' ends. The results of foot-printing experiments using RNase V1 and RNase T2 were in agreement with this model.
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PMID:Identification of the RNA polymerase-binding site on genome RNA of influenza virus. 343 66

The small nuclear RNAs U1, U2, U4, and U5 are cofactors in mRNA splicing and, like the pre-mRNAs with which they interact, are transcribed by RNA polymerase II. Also like mRNAs, mature U1 and U2 RNAs are generated by 3' processing of their primary transcripts. In this study we have investigated the in vitro processing of an SP6-transcribed human U2 RNA precursor, the 3' end of which matches that of authentic human U2 RNA precursor molecules. Although the SP6-U2 RNA precursor was efficiently processed in an ammonium sulfate-fractionated HeLa cytoplasmic S100 extract, the product RNA was unstable. Further purification of the processing activity on glycerol gradients resolved a 7S activity that nonspecifically cleaved all RNAs tested and a 15S activity that efficiently processed the 3' end of pre-U2 RNA. The 15S activity did not process the 3' end of a tRNA precursor molecule. As demonstrated by RNase protection, the processed 3' end of the SP6-U2 RNA maps to the same nucleotides as does mature HeLa U2 RNA.
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PMID:Accurate and efficient 3' processing of U2 small nuclear RNA precursor in a fractionated cytoplasmic extract. 367 Mar 7

A ribonuclease that hydrolyzes either linear duplex or single-stranded RNA in an exonucleolytic manner has been partially purified from Ehrlich ascites tumor cell nucleoli and is free from other ribonucleases. The enzyme will also degrade the RNA complement of an RNA X DNA duplex; however, no nuclease activity is observed on linear duplex or single-stranded DNA. The exonuclease acts on RNA nonprocessively from the 3' end releasing 5'-mononucleotides. The enzyme has a broad pH optimum around pH 8.0, requires Mg2+ or Mn2+ (0.06 mM) for optimum activity, and is sensitive to ethylenediaminetetraacetic acid and N-ethylmaleimide inhibition. Monovalent cations including K+, Na+, and NH4+ are inhibitory. Gel filtration studies of this enzyme gave a Stokes radius of 40 A. Sedimentation velocity measurements in glycerol gradients yield a S20,W of 6.0 S. From these values a native molecular weight of 100 000 was calculated. Copurification of the single- and double-stranded activities, identical reaction requirements, and identical heat-inactivation curves strongly suggest that both activities reside with the same enzyme.
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PMID:Purification and properties of a novel nucleolar exoribonuclease capable of degrading both single-stranded and double-stranded RNA. 399 80

Intracisternal A particles, known primarily for their association with various tumors, have been shown to contain high-molecular-weight (HMW) ribonucleic acid (RNA) by velocity centrifugation, using linear glycerol gradients. This HMW RNA is sensitive to ribonuclease digestion and alkali treatment but is resistant to Pronase treatment. By a double-labeling experiment, HMW RNA was shown to be intrinsic to intracisternal A particles and not to have resulted from cytoplasmic polysomal RNA aggregation. By a reconstitution experiment, it was determined that the results were not due to C-type virus contamination. The synthesis of HMW RNA in intracisternal A particles is inhibited by actinomycin D and ethidium bromide. These observations emphasize that there are probably some taxonomic relationships between intracisternal A particles and oncogenic RNA viruses.
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PMID:Analysis of high-molecular-weight ribonucleic acid associated with intracisternal A particles. 468 4

The effect of concentrated glycerol on the thermal transitions of chymotrypsinogen and ribonuclease has been examined by differential spectrophotometry at 293 and 287 mm, respectively. It was found that for both proteins addition of glycerol raises the transition temperature, the increase in Tm being greater for ribonuclease than for chymotrypsinogen. This increase in the free energy of denaturation appears to reflect primarily a decrease in the entropy change. Analysis in terms of the Wyman linkage equation shows that, for both proteins, the exclusion of glycerol from the protein domain increases on denaturation i.e., the chemical potential of glycerol becomes even more positive when the protein unfolds relative to the native structure. This provides the thermodynamic stabilization free energy. Results of the kinetic examination of the slow unfolding reaction are consistent with the concept that the preferential exclusion of glycerol is related, at least in part, to enhanced solvent ordering.
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PMID:Thermodynamic and kinetic examination of protein stabilization by glycerol. 627 Nov 70

We report here the partial isolation of an RNase activity which copurifies with the nuclear residual structure prepared from both rat liver and Herpes-infected BHK cells. After the successive treatment of purified nuclei with DNase, low salt and high salt, the RNase activity is found both in the high salt soluble supernatant fraction and in the residual nuclear structure. Triton X-100 treatment of this structure solubilizes the RNase activity. From this we conclude that some of the RNase activity associated with the nuclear residual structure may be located in either the phospholipidic or protein moieties that were extracted with Triton X-100. This RNase cuts rRNA non-randomly into characteristic degradation products. Its molecular weight, on a glycerol gradient, was determined to be 25,000.
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PMID:Location of RNase activity in nuclear residual structures. 632 Sep 37

Mitotic apparatuses (MAs) isolated from sea urchin eggs contained clusters of granular material in their centrospheres. After cold treatment and mild agitation, the MA fraction formed asters when combined with tubulin. Many microtubules grew from isolated centrospheres most of which were covered with astral residues. Homogenization of the isolated MA fraction dispersed the centrospheres which broke into fragments or into aggregates of small granules that formed small asters when tubulin was added. Electron microscopy showed that more than ten microtubules were nucleated from a granular aggregate composed of several approximately 90-nm granules. The aster-forming activity was lost with time when the MAs were kept at 0 degree C. Only glycerol stabilized this activity. The aster-forming activity also was heat labile and trypsin sensitive, but it was resistant to RNase treatment. When the dispersed MAs were extracted with a buffer solution of high ionic strength, aster-forming activity was recovered only in the extract; that is, when the extract had been dialyzed against a solution of low ionic strength, the fine granules self assembled and retained their aster-forming ability.
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PMID:Aster formation in vitro is nucleated by granules isolated from the mitotic apparatus. 650 68

Mitotic centrosomes were prepared from Chinese hamster ovary cells and their capacity to nucleate microtubules in vitro was demonstrated by incubation with exogenous brain microtubule protein. The number of microtubules polymerized onto centrosomes was directly counted by electron microscopy of whole-mount preparations. This simple and accurate quantitative assay has permitted characterization of the microtubule nucleating activity of centrosomes in vitro. The number of microtubules polymerized onto centrosomes varied according to the structure of the centrosome. The activity was roughly proportional to the centriole number. The number and length of microtubules nucleated by centrosomes depended both on the concentration of tubulin and the incubation time with tubulin. Under saturating conditions, an average of 200-250 microtubules were initiated by single centrosomes. Centrosomal activity is unstable (t 1/2 = 8 h) and could easily be irreversibly disrupted by a medium of high ionic strength. The activity is stabilized by the addition of glycerol. Centrosomes can be stored at -80 degrees C. The optimum pH for microtubule nucleation is 6.8. Activity is sensitive to protease digestion, but neither DNase or RNase affected the nucleating activity of centrosomes. The activity is temperature-sensitive, but addition of phenylmethylsulphonyl fluoride (PMSF) induces thermal stability. At an optimal concentration of 0.5 mg/ml, this drug increased the half-life of the activity (t 1/2 = 95 h) and made it resistant to salt extraction. Protease inhibitors other than PMSF or dansyl fluoride did not have any stabilizing effect on the activity. The difference between the centrosomal structure of polymerized microtubules in vivo and in vitro is discussed.
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PMID:Activity and stability of centrosomes in Chinese hamster ovary cells in nucleation of microtubules in vitro. 654 Feb 69

Chromatin depleted nuclei ('nuclear matrix') of Ehrlich ascites cells were characterized and fragmented by glycerol shot technique (particle fragmentation). The preparations reveal that 'nuclear matrix' is entirely composed of granules and fibres. Prominent size classes of granules are 10 to 20 nm and 25 to 40 nm, respectively. Most of the granules remain attached to fibres during the fragmentation process. The diameter of the fibres corresponds with double-stranded DNA visualized under identical conditions. The RNP-like nature of the particles is shown by their proteinase K/RNase sensitivity. Since the 'nuclear matrix' architecture becomes instable in high salt buffer after pretreatment with RNase which changes the RNP-particle-like material it must be inferred that the RNP/DNA interaction is a prerequisite for the high salt stability of the 'nuclear matrix' complex.
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PMID:Fragmentation of 'nuclear matrix' on a mica target. 661 72

The binding of [6,7-3H]triamcinolone acetonide (TA) to intestinal mucosa of freshwater-adapted silver eels was studied. The cytoplasmic preparations bound the ligand with an equilibrium dissociation constant (KD) of 2.28 +/- 0.37 nM and the maximal number of binding sites (Nmax) was 960 +/- 55 fmol/mg of protein (+/- SE, n = 13). Scatchard analysis indicated the presence of a single species of binding sites. Binding was abolished following treatment of the cytosol with trypsin, N-ethylmaleimide, or Mersalyl, but DNase or RNase treatment had little effect. The competition hierarchy of radioinert steroids on the formation of the [3H]TA-receptor complex was TA greater than dexamethasone greater than cortisol greater than 11-deoxycortisol. Aldosterone, DOC, corticosterone, 11-dehydrocorticosterone, progesterone, testosterone, or estradiol-17 beta did not compete. Sedimentation of the [3H]TA-receptor complex on a linear sucrose gradient (10-30% + 10% v/v glycerol) yielded single peaks in the absence or presence of 0.4 M KCl in the gradient (6 S or 3.5 S respectively). Following heat activation the receptor-ligand complex was freely translocated to homologous nuclei in vitro, though the activated complex did not bind to DNA-cellulose. It was concluded that the eel intestinal mucosal cytosol contains a high-affinity-low capacity steroid receptor system. This is the first instance that such a system was demonstrated in fish tissue.
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PMID:Intestinal triamcinolone acetonide receptors of the eel (Anguilla rostrata). 661 55


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