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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Even a small amount of formaldehyde is shown to induce a drop in the RNase A enzymatic activity. This drop is rapid from the start and then begins to be slower. A supposition was made on nature of the enzyme activity. Comparison of the effects of formaldehyde on the enzymatic and the destabilizing activity of RNase A was made. The effect of formaldehyde on the enzymatic activity does not correlate with its effect on the ability of RNase to destabilize the DNA double helix.
Mol Biol (Mosk)
PMID:[Effect of formaldehyde on the enzymatic activity of RNAase A]. 56 74

Using phenol fractionation in the absence of detergents three DNA fractions differing by the incorporation of radioactive thymidine after pulse label are obtained from regenerating rat liver cells. Two fractions extracted under variety of conditions represent the main bulk of cell DNA (85--90%). DNA non-extractable under conditions used (DNA III) incorporates labelled thymidine 10--15 times faster than the first two DNA fractions. DNA III purified from the interphase layer by pronase, sodium dodecylsulfate and phenol sediments at 26S and has a hyperchromic effect about 40% after alkaline denaturation. Alkaline sucrose density gradient centrifugation of pulse-labelled DNA III revealed that nascent DNA consisted of heterogeneous fragments similar in size to the replication fragments in bacterial cells (9--10S). It was shown by CsCl equilibrium centrifugation that buoyant density of heat denatured DNA III labelled for 5 min with [3H]thymidine is heavier than the bulk of DNA prelabelled for 2 h with [14C]thymidine. After hydrolysis with RNase or alkali, buoyant densities of both DNAs became the same. These results support the idea of initiating role of RNA in the synthesis of discontinuous replicating fragments in regenerating rat liver cells. Specific radioactivity of RNA associated with replication fragments which are labelled for 5 min with [14C] orotic acid is 20 times more than of the same RNA labelled for 30 min. These data demonstrate high metabolic activity of initiating RNA.
Mol Biol (Mosk)
PMID:[Properties of replicating DNA in the regenerating rat liver isolated during phenol fractionation]. 61 27

The rate constants and Km for the hydrolysis of the optically active nonglycosidic analogues of the CpA and C greater than p catalysed by RNase A and RNase BS-I were measured. The rate of hydrolysis of the model substrates in 10(5) and 10(3) slower that for the appropriate dinucleoside phosphate and nucleoside cyclophosphate. However, substitution of the relatively rigid ribofuranose ring with flexible alifatic chains is accompanied by little variation in binding constants. The analyses based on the single substrate system indicate that the observed difference in rate constants must be accounted for by a difference between the binding of the substrates in the transition state to the RNase active site. Consequently, the "rigidity" of the ribose rings in RNA leads to large decreases in the free energy of activation for the reactions catalysed by RNases.
Mol Biol (Mosk)
PMID:[Role of the ribose residue of substrates in reactions catalyzed by ribonuclease]. 68 97

Coliphage BF23 develops in Salmonella typhimurium rough strains. The phage is neither restricted nor modified by S. typhimurium. The growth patterns of the phage were slightly different in S. typhimurium than in Escherichia coli, although phage propagated on S. typhimurium is identical to the phage propagated in E. coli by several criteria used. Mutants of S. typhimurium resistant to BF23 were isolated and found to map (by P22- and Pl-mediated transduction) in the same position as bfe mutants of E. coli. The order of genes was: metB - argC - bfe - rif - purD - metA. Phage BF23 does not form plaques on smooth S. typhimurium strains, since the phage fails to adsorb irreversibly to smooth cells. Nevertheless, on solid agar, the phage prevents growth of many (but not all) smooth strains. Moreover, UV- and alkali-inactivated phage BF23, although unable to form plaques on sensitive hosts, retains the ability to prevent growth of the host on solid medium. This ability is sensitive to protease and resistant to DNAse and RNase. Heat treatment of the phage causes rapid loss of the cell-growth-preventing-ability whereas the ability to form plaques is lost much more slowly. These results lead to a proposal that phage BF23 virions carry a colicin-like factor that kills sensitive cells.
Mol Gen Genet 1976 Aug 19
PMID:Growth of coliphage BF23 on rough strains of Salmonella typhimurium: the bfe locus. 78 57

Exponential growing Tetrahymena pyriformis organisms were labelled with (3H) uridine or (3H) adenosine. The labelled RNA was extracted and isolated by affinity chromatography on poly-uridylic-acid sepharose and further analysed by means of sucrose gradient centrifugation and RNase digestion. Experimental evidence proved the existence of RNase resistant poly adenylic-acid fragments in the RNA of Tetrahymena cells. This poly adenylic-acid segment has a sedimentation rate of 4-5 S and would be localised in the 10-12S region of the RNA which is probably the m-RNA.
J Mol Evol 1976 Aug 03
PMID:Fractionation of RNA from tetahymena by affinity chromatography on poly-U-Sepharose. 82 41

The total poly(A)-containing mRNA from mouse liver or Ehrlich ascites carcinoma cells was annealed with denatured ds RNA prepared from heavy nuclear 3H-labeled pre-mRNA of the same tissue. The hybrids formed were detected by binding of complexes to poly(U)-Sepharose columns through the poly(A) of mRNA. With this technique, about 30% of labeled ds RNA was bound to poly(U)-Sepharose after annealing it with an mRNA excess. The proportion of hybrid material detected by RNase treatment was two to three times lower than that obtained by poly(U)-Sepharose binding. The length of the RNase-stable acid precipitable hybrid material consisted of heterogeneous sequences of 10-100 nucleotides long when cytoplasmic, and 10-60 nucleotides long when polysomal mRNA was used in the hybridization reaction. The results obtained show that at least some of the mRNA molecules contain sequences complementary to one of the branches of the pre-mRNA hairpins. These results are compatible with the idea that the hairpin-like sequences in pre-mRNA are localized between mRNA and the non-informative part of the precursor molecule.
Mol Biol Rep 1976 Apr
PMID:Direct demonstration of a complementarity between mRNA and double-stranded sequences of pre-mRNA. 127 59

Based upon our previous report indicating the presence of retrovirus-like particles in human gastric cancer cells, we analyzed the putative endogenous reverse transcriptase activity these particles should have. To evaluate the specificity of reverse transcription over that displayed by normal cellular DNA polymerases, the following discriminatory criteria were used: 1) resistance to high concentrations of Actinomycin D; 2) sensitivity to preincubation with ribonuclease A; 3) behavior in cesium sulfate isopycnic gradients and 4) size-shifting of putative template-product complexes after RNase exposure in agarose gel electrophoresis. We report a significant endogenous reverse transcriptase activity associated with membrane-encapsidated particles from terminally-illed patients but not in normal counterparts. Although these structures closely resemble retro viruses, a new model is proposed to explain our findings.
Cell Mol Biol (Noisy-le-grand) 1992 Nov
PMID:Further characterization of RNA-dependent-DNA polymerase activity in human gastric cancer. 128 60

Insulin-like growth factor II (IGF-II) cDNA was isolated from adult guinea pig liver by polymerase chain reaction (PCR) screening. A cDNA sequence was obtained corresponding to part of the preproIGF-II, including the signal peptide, the mature IGF-II and 37 amino acids of the acid carboxy-terminal E-domain. Amino acid sequence prediction, based on the cDNA clone, showed that mature guinea pig IGF-II has a high homology with both human and rat IGF-II, 100 and 94% identity, respectively. Levels of IGF-II mRNA in guinea pigs of different ages were analyzed by solution hybridization/RNase protection assay using part of the isolated IGF-II cDNA as a probe. There is a marked developmental regulation of IGF-II after birth. IGF-II mRNA levels were high in fetal livers, and decreased 15- to 30-fold in adults. As in man, but in contrast to rats, adult guinea pigs have significant levels of IGF-II mRNA in the liver. In fetal guinea pigs, the expression of IGF-II mRNA was 5-, 2- and 70-fold lower in kidney, skeletal muscle and brain cortex, respectively, than in liver. IGF-II mRNA levels in kidney and skeletal muscle of fetal guinea pigs were 5- and 4-fold higher, respectively, compared with adults. Similar sizes of IGF-II mRNA transcripts could be observed on Northern blots in newborn rats and in fetal guinea pigs. Our conclusions are that the mature IGF-II peptide in the guinea pig is 100% identical to the mature peptide in the human.(ABSTRACT TRUNCATED AT 250 WORDS)
Mol Cell Endocrinol 1992 Nov
PMID:Isolation of an insulin-like growth factor II cDNA from guinea pig liver: expression and developmental regulation. 130 79

Steady state levels of the mRNA coding for the neurotransmitter biosynthetic enzyme, acetylCoA-choline-O-acetyltransferase (ChAT, EC 2.3.1.6), were measured in wild type Drosophila and two temperature-sensitive mutants (Chats1 and Chats2) using the RNase protection method. At a permissive temperature the relative amounts of ChAT mRNA were: wild type: Chats1:Chats2 = 1:2.09 (+/- 0.39):3.37 (+/- 0.57) (mean +/- S.E.M.) indicating that mutant flies may compensate, for making a thermolabile form of enzyme, by producing and/or maintaining higher levels of ChAT mRNA. At a restrictive temperature the ChAT mRNA levels decreased in both mutants and increased in wild type flies. The regulatory mechanism(s) responsible for increasing ChAT mRNA in wild type flies appears to have failed in the mutants at high temperature. Steady state mRNA levels were also measured in embryonic cell cultures prepared from wild type embryos. Cultures grown in the presence of two pharmacologic agents (carbamylcholine and d-tubocurarine) which should interfere with cholinergic neurotransmission, showed less mRNA resulting from a decrease in levels of ChAT gene transcription. Our results imply that neurotransmission and the rate of neurotransmitter biosynthetic enzyme gene transcription are coupled for the cholinergic system in Drosophila.
Brain Res Mol Brain Res 1992 Apr
PMID:Positive and negative feedback regulation of choline acetyltransferase mRNA levels in Drosophila: a study using temperature-sensitive mutants and embryo cell cultures. 131 95

In rat pituitary GH3 cells, thyrotropin-releasing hormone (TRH) down-regulates TRH receptor (TRH-R) mRNA (Fujimoto, J., Straub, R.E., and Gershengorn, M.C. (1991) Mol. Endocrinol. 5, 1527-1532), at least in part, by stimulating its degradation (Fujimoto, J., Narayanan, C.S., Benjamin, J.E., Heinflink, M., and Gershengorn, M.C. (1992) Endocrinology 130, 1879-1884). Here we show that TRH regulates RNase activity in GH3 cells and that specific mRNA sequences are needed for in vivo regulation of TRH-R mRNA by TRH. TRH affected RNase activity in a biphasic manner with rapid stimulation (by 10 min) followed by a decrease to a rate slower than in control lysates within 6 h. This time course paralleled the effects of TRH on degradation of TRH-R mRNA in vivo. The regulated RNase activity was in a polysome-free fraction of the lysates and was not specific for TRH-R RNA. A truncated form of TRH-R RNA that was missing the entire 3'-untranslated region (TRHR-R5) was more stable than full-length TRH-R RNA (TRHR-WT). In contrast to TRHR-WT mRNA, TRHR-R5 mRNA and TRHR-D9 mRNA, which was missing the 143 nucleotides 5' of the poly(A) tail, were not down-regulated by TRH in stably transfected GH3 cells as their rates of degradation were not increased. These data show that TRH regulates RNase activity in GH3 cells, that the 3'-untranslated region bestows decreased stability on TRH-R mRNA and that the 3' end of the mRNA is necessary for regulation by TRH of TRH-R mRNA degradation. We present an hypothesis that explains specific regulation of TRH-R mRNA degradation by TRH in GH3 pituitary cells.
 ...
PMID:Regulation by thyrotropin-releasing hormone (TRH) of TRH receptor mRNA degradation in rat pituitary GH3 cells. 132 30


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