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)

A cell-free system was developed and characterized, which supported RNA release from isolated rat liver cell nuclei. The RNA release in the system seemed to be dependent on the presence of ATP as an evergy source and of dialized cytosol as far as on the temperature level in the incubation mixture. In vitro effects of a number of RNase affectors from cytoplasm and of related exogenous compounds on the RNA release were studied. It was shown that RNase inhibitors such as heparin, PVS and rat liver cytoplasmic RNA were capable to stimulate the RNA release, while the natural inhibitor from liver cytosol failed to influence the RNA relase. Spermidine and PCMB lowered the rate of RNA release from nuclei. The results are discussed in connection with possible role of nuclear RNases and cytoplasmic factors in nucleocytoplasmic transport of RNA.
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PMID:[RNA transport from rat liver cell nuclei in vitro. Release of rapidly labeled RNA from isolated nuclei in a cell-free system in the presence of RNAse affectors]. 74 5

Serum contains a sugar transferase which is able to catalyse the glycosylation in vitro of the asparagine residue present in the sequence Asn.Leu.Thr in bovine pancreatic ribonuclease. UDP-2-Acetamido-2-deoxy-D-glucose (UDP-N-acetyl-D-glucosamine) acts as a donor, although the mechanism of the transfer is unexplored. Spermidine and Mn2+, as well as CDP-choline, can act as activators for the reaction. Monoglycosylated ribonuclease (ribonuclease-GlcNAc) has been separated (23% yield) from unreacted ribonuclease A by affinity chromatography on a column of wheat-germ agglutinin bound to Sepharose, and characterised. A possible reason for the presence of the enzyme in serum is suggested.
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PMID:UDP-N-acetyl-D-glucosamine-asparagine sequon N-acetyl-beta-D-glucosaminyl-transferase-activity in human serum. 98 74

Estrogenic regulation of gene expression involves interaction of the hormone with its receptors, which undergo structural and conformational changes to interact with specific DNA sequences. Putrescine, spermidine, and spermine, are ubiquitous cellular components. We studied the effects of these polyamines on rabbit uterine estrogen receptors by sucrose gradient centrifugation and ligand dissociation kinetics. The native 7S receptor converted to a 9S-10S form in the presence of 100 microM spermidine or spermine. Higher concentrations caused precipitation of the receptor. This precipitation was reduced by RNase treatment of the receptor. RNase-treated receptors sedimented at 4S and 7S regions of sucrose gradient. The dissociation rate constant (k) of the 4S receptor is 2.8 X 10(-3) min-1 in the presence of 1 mM spermidine, compared to a control value of 7.7 X 10(-3) min-1. Similar effects were observed with putrescine and spermine. The dissociation of the RNase-treated 7S receptor was biphasic, with about 50% of the receptors dissociating at a faster rate (k1 = 40 X 10(-3) min-1) than the other half (k2 = 7.4 X 10(-3) min-1). Spermidine (1 mM) caused a 2-fold reduction in k2, whereas k1 was not affected. This study shows that polyamines affect the structural organization and ligand dissociation kinetics of estrogen-receptor complexes.
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PMID:Structural alterations and stabilization of rabbit uterine estrogen receptors by natural polyamines. 381 74

1. Ribosomes isolated from the cortex tissue of goat brain contain very small amounts of spermidine and spermine. Ribosomes isolated from spermidine-treated slices have a higher spermidine content. 2. The polyamines partially prevent the temperature-dependent breakdown of ribosomes into acid-soluble nucleotides. 3. The ;melting' temperature of ribosomes rises slightly when the ribosomes are heated slowly in the presence of polyamines. 4. The pH-dependent breakdown of ribosomes into protein, RNA and acid-soluble nucleotide is markedly decreased by polyamines present in media in which ribosomes are suspended. 5. The breakdown of ribosomes in the presence of high concentrations of salts and EDTA is partially checked by the concurrent presence of polyamines. 6. Spermidine and spermine make ribosomes less susceptible to enzymic digestion by crystalline trypsin and ribonuclease.
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PMID:Effect of polyamines on the stability of brain-cortex ribosomes. 498 Oct 36

1. The effect of spermidine on the mescaline-induced changes of brain-cortex ribosomes was studied by adding spermidine during the treatment of goat brain-cortex slices with mescaline. 2. Mescaline treatment of brain-cortex slices removed a portion of the endogenous spermidine from ribosomes and this removal was significantly prevented when spermidine was present during mescaline treatment. 3. Spermidine present during mescaline treatment of brain-cortex slices counteracted, to some extent, the destabilizing effect of mescaline on ribosomes with respect to heat denaturation. 4. Mescaline treatment of brain-cortex slices made ribosomes more susceptible to breakdown, releasing protein and RNA, and resulting in loss of ribosomal enzymic activities. However, spermidine present during mescaline treatment counteracted moderately the mescaline-induced ribosomal susceptibility to breakdown and ribosomal loss of enzymic activities. 5. Ribosomes of mescaline-treated cortex slices were rapidly degraded by ribonuclease and trypsin. However, if spermidine was present during mescaline treatment of brain-cortex slices the rates of degradation diminished.
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PMID:Mescaline-induced changes of brain-cortex ribosomes. Role of sperimidine in counteracting the destabilizing effect of mescaline of brain-cortex ribosomes. 515 7

A nucleolar ribonuclease specific for single-stranded ribonucleic acid (RNA) has been isolated and extensively purified from Ehrlich ascites carcinoma cells. The enzyme is optimally active at neutral pH and degrades RNA via a 2',3'-cyclic intermediate leaving 3'- or 2',3'-cyclic terminated oligonucleotides. The ribonuclease has an apparent molecular weight of 38 500 as judged by sedimentation equilibrium and is a basic protein having an isoelectric point greater than 9.0. The enzyme preferentially cleaves poly(C) over poly (U), poly(A), or poly(C).poly(I). Limit digestion products of poly(C) degratation are on the average tri-, tetra-, and pentanucleotides. In the partial digestion of yeast 5.8S rRNA, the nucleolar ribonuclease cleaves only CpA phosphodiester bonds. Spermidine, spermine, and histone I inhibit the activity of nucleolar ribonuclease. Antibodies directed toward pancreatic RNase do not cross-react with the Ehrlich nucleolar ribonuclease.
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PMID:Properties of a purified nucleolar ribonuclease from Ehrlich ascites carcinoma cells. 739 14

We previously suggested that the degree of polyamine stimulation of oligopeptide-binding protein (OppA) synthesis is dependent on the secondary structure and position of the Shine-Dalgarno (SD) sequence of OppA mRNA. To study the structural change of OppA mRNA induced by polyamines and polyamine stimulation of initiation complex formation, four different 130-mer OppA mRNAs containing the initiation region were synthesized in vitro. The structural change of these mRNAs induced by polyamines was examined by measuring their sensitivity to RNase T(1), specific for single-stranded RNA, and RNase V(1), which recognizes double-stranded or stacked RNA. In parallel, the effect of spermidine on mRNA-dependent fMet-tRNA binding to ribosomes was examined. Our results indicate that the secondary structure of the SD sequence and initiation codon AUG is important for the efficiency of initiation complex formation and that spermidine relaxes the structure of the SD sequence and the initiation codon AUG. The existence of a GC-rich double-stranded region close to the SD sequence is important for spermidine stimulation of fMet-tRNA binding to ribosomes. Spermidine apparently binds to this GC-rich stem and causes a structural change of the SD sequence and the initiation codon, facilitating an interaction with 30 S ribosomal subunits.
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PMID:Polyamine stimulation of the synthesis of oligopeptide-binding protein (OppA). Involvement of a structural change of the Shine-Dalgarno sequence and the initiation codon aug in oppa mRNA. 1042 55

Surfactant protein D (SP-D) appears to play an important role in regulating local pulmonary inflammatory responses to pathogens. There is also in vitro evidence that SP-D may suppress local T cell responses. However, the role of SP-D in regulating T cell responses directly in the lung has not been previously evaluated in vivo. SP-D(-)(/-) mice demonstrate peribronchial and perivascular accumulations of lymphocytes. Therefore, we investigated the functional status and abundance of intrapulmonary lymphocytes in SP-D(-)(/-) mice. By morphometric analysis, SP-D(-)(/-) mice demonstrated increased numbers of airway- and vessel-associated lymphocytes without increases in interstitial lymphocytes. There was increased proliferative activity of lymphocytes isolated by enzymatic disassociation of minced lung. Flow cytometry was used to determine the number and functional activation status of intrapulmonary CD4(+) and CD8(+) T cells, as well as B cells and NK cells. Cytokine expression patterns in lung tissues were evaluated using RNase protection assays, reverse transcriptase/polymerase chain reaction, and enzyme-linked immunosorbent assay. There was marked T cell activation in the lungs of SP-D(-)(/-) mice, as reflected by an increased percentage of both CD4(+) and CD8(+) T cells expressing CD69 and CD25. BAL CD4 lymphocytes were increased and the fraction expressing CD69 was also increased. Although there were increases in BAL CD8 lymphocytes, apparent increases in CD69-positive CD8 lymphocytes did not reach statistical significance. In contrast, splenic T cells were not activated in SPD(-)(/-) mice. Of the proinflammatory cytokines evaluated, only interleukin (IL)-12 and IL-6 expression were consistently upregulated in the lungs of SPD(-)(/-) mice. Increased IL-2 expression was apparent but did not reach statistical significance. We conclude that the lack of local pulmonary production of SP-D leads to a state of persistent T cell activation, possibly in response to exogenous antigens. This study therefore provides further evidence of the important local immunoregulatory role of SP-D in vivo.
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PMID:Lymphocyte activation in the lungs of SP-D null mice. 1209 Dec 42