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:3.1.26.9 (ribonuclease)
6,589 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A standardized bioassay for transfer of Fv-1 gene-specific resistance to N-tropic and B-tropic murine retroviruses was developed using X plaque reduction in SC-1 (Fv-1-) cells inoculated with virus. Testing of subcellular fractions of restrictive cells showed that the resistance transfer activity was present in the cytoplasmic (microsomal and cytosol) fractions. The activity of the cytoplasmic extract was destroyed by treatment with ribonuclease, but not with deoxyribonuclease or proteases. RNA prepared by phenol-chloroform extraction of mouse tissues, including embryos and livers of weanling mice, transferred Fv-1 locus-specific resistance into DEAE-dextran-treated SC-1 cells. The activity of isolated RNA preparations against virus of the appropriate host-range type has been demonstrated to correspond to the Fv-1 genotypes of the cell sources. The specific transfer of resistance with cellular RNA was effective within a 5- to 6-h period from 2 h before to 4 to 5 after virus infection. Sucrose gradient centrifugation of the RNA showed that the activity sedimented as a broad peak, with an apparent maximum in the 22S region. Affinity chromatography of whole-cell RNA on polyuridylic acid-Sepharose tended to separate more activity into the polyadenylic acid RNA fraction than the non-polyadenylic acid RNA fraction. Except for the reciprocal inhibitory activity for the two host-range virus types, the RNAs of Fv-1n and Fv-1b specificities showed similar properties in all aspects studied.
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PMID:Transfer of Fv-1 locus-specific resistance to murine N-tropic and B-tropic retroviruses by cytoplasmic RNA. 21 Dec 61

Undegraded rat liver polysomes were obtained after homogenizing the tissue in a medium containing NH4Cl, heparine, and yeast tRNA. Purification of poly(A)-containing RNA from polysomal RNA was accomplished by affinity chromatography on oligo(dT)-cellulose columns. Poly(A)-containing RNA molecules were monitored by the formation of ribonuclease-resistant hybrids with [3H]poly(U). To improve the separation of messenger RNA and ribosomal RNA by oligo(dT)-cellulose it was found essential to dissociate the aggregates formed between both molecular species by heat treatment in the presence of dimethylsulfoxide (Me2SO) prior to chromatography. Sucrose gradient analysis under denaturing conditions showed that the preparations obtained were virtually free of ribosomal RNA. Poly(A)-containing RNA constituted approx. 2.2% of the total polysomal RNA and the number average size was 1500--1800 nucleotides, as judged by sedimentation analysis on sucrose density gradients containing Me2SO. Approximately 8.2% of the purified preparation obtained was able to anneal with [3H]poly(U); the number average nucleotide length of the poly(A) segment of the RNA population was calculated to be 133 adenylate residues. Based on these values, our preparations appear to be greater than 90% pure. The RNA fractions obtained after oligo(dT)-cellulose chromatography were used to direct the synthesis of liver polypeptides in a heterologous cell-free system derived from wheat-germ. The system was optimized with respect to monovalent and divalent cations, and presence of polyamines (spermine). More than 65% of the translational activity present in the unfractionated polysomal RNA was recovered in the final poly(A)-containing RNA fraction. However, about 25% of the activity was found to be associated with the unbound fraction which was essentially free of poly(A)-containing RNA. Immunoprecipitation analysis with a specific antiserum to rat serum albumin demonstrated that about 6--8% of the labeled synthetic products translated from the poly(A)-containing RNA sample corresponded to serum albumin. Analysis of the translation products by sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed a heterogeneous distribution of molecular sizes ranging from 15 000 to greater than 70 000 daltons. Spermine not only increased the overall yield and extent of protein synthesis, but also resulted in higher yields of large protein products. Under optimal translation conditions a discrete peak representing about 7% of the total radioactivity was observed to migrate with rat serum albumin.
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PMID:Isolation and characterization of poly(adenylic acid)-containing messenger ribonucleic acid from rat liver polysomes. 66 61

Nuclei of GH3 cells, isolated by detergent lysis, synthesized RNA for an extended period at 29 degrees C in the presence of rat liver ribonuclease inhibitor (RI). Extended RNA synthesis was dependent upon the presence of RI. Sucrose gradient sedimentation analysis of the cell-free reaction products showed that RNAs ranging from 4 S to greater than 28 S were synthesized. Further characterization of the RNA products was made by examining the sensitivity of synthesis to alpha-amanitin and actinomycin D as well as by oligo(dT)-cellulose binding properties. Evidence was obtained that RNA polymerases I, II, and III were functioning in isolated GH3 nuclei. Newly synthesized RNAs were found in both the nuclear pellet and postnuclear supernatant fractions. RNA polymerase I products remained associated with the nuclear pellet throughout a 60-min incubation period whereas RNAs synthesized by RNA polymerase III emerged rapidly into the supernatant fraction. RNA polymerase II products were distributed in both fractions and were found to contain poly(A). De novo poly(A) synthesis was demonstrated and found to be inhibited by cordvcepin triphosphate (3'-dATP). Supernatant RNAs synthesized by polymerase II contained a poly(A) segment of about 150 adenine residues; these transcripts sedimented heterogeneously with an apparent size distribution (under denaturing conditions) which was smaller than that of nuclear RNA polymerase II products and which resembled that of cellular mRNA. Qualitative differences in the nuclear and supernatant RNAs, the kinetics of appearance of the latter, and the differential effect of 3'-dATP on the extranuclear appearance of supernatant RNAs suggest that a process resembling nuclear-cytoplasmic RNA transport occurred in this cell-free nuclear system.
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PMID:Extended RNA synthesis in isolated nuclei from rat pituitary tumor cells. 98 56

The administration of ethionine to female rats causes breakdown of hepatic polysomes. The state of mRNA and monomeric ribosomes after the polysome dissociation was studied. The mRNA was selectively labeled with [14C] orotate after a low dose of actinomycin D. Sucrose density gradient centrifugation of Triton X-100-treated cytoplasm revealed an accumulation of heterodisperse radioactive material with very large S values. This material was converted to smaller S values with deoxycholate treatment and was extremely sensitive to mild ribonuclease treatment. Since this material was banded at around 1.43 g/cm3 in CsCl gradient centrifugation and contained RNA with a distribution of S values characteristic of polysomal mRNA, this material was identified as mRNA-containing ribonucleoprotein particles. The monomeric ribosomes were shown to be dissociated into subunits in the presence of 0.5 M KCl, indicating that these lacked nascent polypeptide chains. When the animals were recovered from the ethionine treatment by subsequent administration of adenine and methionine, the heterodisperse ribonucleoprotein particles and monomeric ribosomes appeared to be utilized for the reformation of polysomes.
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PMID:The state of messenger ribonucleic acid and ribosomes in the cytoplasm of ethionine-treated rat liver. 111 2

An inhibitor of ribonucleic acid polymerases has been obtained from the mycelial phase of Histoplasma capsulatum and partially characterized. The inhibitor, called histin, was purified 200-fold by heat treatment at 100 C and electrophoresis on polyacrylamide gels. Histin moved in electrophoresis as if negatively charged; it was insensitive to treatment with ribonuclease of deoxyribonuclease but was completely digested by Pronase. Sucrose gradient centrifugation suggests a molecular weight of 24,000. The possibility of a regulatory role for histin in the life cycle of H. capsulatum is discussed.
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PMID:Characterization of an inhibitor of ribonucleic acid polymerase from the mycelial phase of Histoplasma capsulatum. 112 17

We have investigated the ability of dehydroepiandrosterone (DHEA) to alter the production of interleukin-2 (IL-2) and to bind to a specific binding complex in antiCD3 epsilon activated T cells. Binding activity correlated with the presence of a specific DHEA binding complex in the cytosol and nuclei of DHEA-responsive T-cell hybridomas, as well as in CD4+ and CD8+ cells isolated from peripheral lymph nodes of normal mice. Scatchard analysis determined that intact lymphocytes and cytosolic fractions contained high affinity binding for [3H]DHEA (approx. 2.6 nM) with 1000-7000 binding sites existing per cell. Five of the T-cell hybridomas tested both responded to DHEA treatment with increased production of IL-2 and also contained specific high affinity [3H]DHEA binding. Four additional T-cell hybridomas were found to contain no specific [3H]DHEA binding and were also unresponsive to DHEA influences on IL-2 production. Sucrose density gradients demonstrated a 3-4s [3H]DHEA binding complex in high salt and a 7-8s binding complex in low salt. Specific binding was inhibited by preincubation of the cytosol fractions with either trypsin or chymotrypsin, or by heating to 60 degrees C for 1 h (less than 15% of control). [3H]DHEA binding was unaffected by preincubation of the cytosol fractions with ribonuclease, deoxyribonuclease, or phospholipase A. The DHEA-protein complexes bound to DNA-cellulose with the amount of binding being slightly increased by preincubation at 25 degrees C as compared to 4 degrees C. As expected, [3H]DHEA binding was inhibited by the addition of unlabeled DHEA, but was also modestly inhibited by dihydrotestosterone and cortisol. Binding of DHEA was unaffected by progesterone, dexamethasone, estradiol, androsterone, DHEAS, and beta-etiocholanolone at all concentrations tested. DHEA was incapable of inhibiting the binding of [3H]DHT to the androgen receptor or [3H]dexamethasone to the glucocorticoid receptor. Collectively, these findings suggest that murine T cells contain a specific DHEA receptor. We believe that DHEA is a steroid hormone that is directly involved in the regulation of IL-2 production by both normal and some T-cell hybridomas.
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PMID:The presence of a dehydroepiandrosterone-specific receptor binding complex in murine T cells. 135 1

A method is described for separation of polyribosomes from as few as 25 isolated Islets of Langerhans, representing about 250 mug of pancreatic tissue. Islets are labeled with [(3)H]leucine and polysomes are isolated with liver polyribosomes, which serve as carrier and inhibitor of ribonuclease activity. Islets incubated at 37 degrees C for 45 min in 15.5 mM glucose, then pulsed with [(3)H]leucine, incorporated about 2-3 times more label into nascent peptides on islet polysomes than islets incubated in 2.8 mM glucose. Sucrose gradient analysis of the labeled polysomes indicated that raising the glucose concentration preferentially stimulated synthesis of peptides on trisomes and larger polyribosomes. Islets incubated with [(3)H]leucine for 15 min incorporated two-thirds of the label into proteins on membrane-bound polysomes. At least 85% of the proinsulin synthesis during this time occurs on membrane-bound polysomes.
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PMID:Insulin biosynthesis: studies of Islet polyribosomes (nascent peptides-sucrose gradient analysis-gel filtration). 455 Nov 47

A specific binding site for somatotropin was solubilized by 1% (v/v) Triton X-100 from a crude particulate membrane fraction of pregnant rabbit liver, partially purified and characterized. The solubilized binding site retained many of the characteristics observed in the original particulate fraction, indicating that extraction of the binding site with Triton X-100 does not cause any major changes in its properties. The binding of human 125I-labelled-somatotropin to the solubilized binding site is a saturable and reversible process, depending on temperature, incubation time, pH and ionic environment. Analysis of the kinetic data revealed a finite number of binding sites with an affinity constant of 0.32 x 10(10)M-1. The binding activity for human 125I-labelled-somatotropin was adsorbed to a concanavalin-A-Sepharose column and was dissociated from the column with alpha-methyl-D-glucoside, suggesting that the binding protein may be a glycoprotein. Using affinity chromatography on concanavalin-A-Sepharose, ion-exchange chromatography on DEAE-cellulose and gel filtration on Sepharose 6B, the binding protein was purified 1000-4000-fold from the original liver homogenate. When the partially purified preparation was chromatographed on Sepharose 6B, the binding protein eluted as a molecule with an apparent molecular weight of 200000, with a Stokes' radius of 4.9 nm. Sucrose-density-gradient centrifugation of the preparation showed that the sedimentation coefficient of the binding protein was 7.2S. Isoelectric focusing experiments revealed that a major part of the protein has an acidic pI (4.2-4.5). Exposure of the protein to trypsin decreased the binding activity for human 125I-labelled-somatotropin or bovine 125I-labelled-somatotropin, whereas ribonuclease, deoxyribonuclease, phospholipase C or neuraminidase had little or no effect.
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PMID:Characteristics of solubilized human-somatotropin-binding protein from the liver of pregnant rabbits. 624 70

A monoclonal antibody from clone T7 raised against total nuclear proteins from the Kc cell line of Drosophila melanogaster (Saumweber, H. Symmons. P. Kabisch, R. Will, H & Bonhoeffer, F, Chromosoma 80 (1980) 253) [1] showed positive immunofluorescent staining on interphase nuclei of HeLa and PTK2 cells. When this antibody was allowed to react with several nuclear protein fractions isolated from HeLa S3 cells, three polypeptides of molecular weights (MW) 44 000, 63 000 and 70 000 were identified as the corresponding antigens, all components of hnRNA containing ribonucleoprotein particles. Sucrose gradient fractionation of such particles after mild RNase treatment and subsequent analysis of the proteins by the immunoblotting method revealed that the 44 000 MW antigen was an integral part of the ribonuclease-resistant complex. The results support the view that hnRNA molecules are associated with certain proteins conserved during evolution which may play structural roles in the ribonucleoprotein organization.
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PMID:Cross-reaction of hnRNP-proteins of HeLa cells with nuclear proteins of Drosophila melanogaster demonstrated by a monoclonal antibody. 681 36

The interactions between proteins and solvent components have been investigated for the sucrose/water system. Thermodynamic and kinetic measurements of the thermal unfolding of alpha-chymotrypsin, chymotrypsinogen, and ribonuclease were performed as a function of sucrose concentration. The alteration in protein-solvent interactions in the presence of sucrose was also studied by density measurements and analyzed by multicomponent thermodynamic theory. Sucrose does not induce a conformational change in three proteins studied, although it does induce a small change in the circular dichroism spectrum of ribonuclease. The enthalpy of thermal unfolding shows little dependence on the concentration of sucrose, while the apparent activation energy of the unfolding process is increased by the addition of sucrose. The results from the protein-solvent interaction study indicate that sucrose is preferentially excluded from the protein domain, increasing the free energy of the system. Thermodynamically this leads to protein stabilization since the unfolded state of the protein becomes thermodynamically even less favorable in the presence of sucrose. The exclusion of sucrose from the protein domain seems to be related to the higher cohesive force of the sucrose water solvent system since all the experimental observations can be correlated with the effect of sucrose on the surface tension of water.
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PMID:The stabilization of proteins by sucrose. 725 92


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