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)

Poly(A)-containing messenger RNA isolated from rabbit reticulocytes as estimated by periodate oxidation and condensation with [3H]isoniazid has two oxidizable end groups per molecule of mol. wt. 220000. When the mRNA is subjected to stepwise degradation by beta-elimination, only one oxidizable end-group is found. This indicates that one of the 2',3' hydroxyl end-groups is linked through the normal 3'--5' phosphodiester bond, but that the other is linked in such a way that after stepwise degradation no new 2',3 hydroxyl group is revealed. This structure could be a 5'-linked 5'-phospho di- or tri-ester. On digestion with ribonuclease the isoniazid-labelled RNA produced oligonucleotide hydrazones consistent with a poly(A) sequence at the 3' end plus fragments that are not found after stepwise degradation. These fragments have a charge of --6 and --8 from pancreatic ribonuclease or --7 from ribonuclease T1 digestion. These charges are changed to --3.4 and --4.1 after pancreatic ribonuclease, ribonuclease T2 and alkaline phosphatase digestion. methyl-3H-labelled-poly(A)-containing RNA isolated from late erythroid cells contain a methyl-labelled fragment resistant to endonuclease and phosphodiesterase II digestion. After digestion with phosphodiesterase I this fragment produces methyl-3 H-labelled nucleotides with the electrophoretic mobility of pm7G and pAm. It is concluded that globin mRNA has the 5' sequences m7G(5')ppp'AmpYpGp ... and m7G(5')pppAmpApGpYp.
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PMID:The nature of the 5'-linked 5' nucleotide sequence at the 5' end of rabbit globin messenger ribonucleic acid. 94 25

The 42S RNA from Semliki Forest virus contains a polyadenylate [poly(A)] sequence that is 80 to 90 residues long and is the 3'-terminus of the virion RNA. A poly(A) sequence of the same length was found in the plus strand of the replicative forms (RFs) and replicative intermediates (RIs) isolated 2 h after infection. In addition, both RFs and RIs contained a polyuridylate [poly(U)] sequence. No poly(U) was found in virion RNA, and thus the poly(U) sequence is in minus-strand RNA. The poly(U) from RFs was on the average 60 residues long, whereas that isolated from the RIs was 80 residues long. Poly(U) sequences isolated from RFs and RIs by digestion with RNase T1 contained 5'-phosphorylated pUp and ppUp residues, indicating that the poly(U) sequence was the 5'-terminus of the minus-strand RNA. The poly(U) sequence in RFs or RIs was free to bind to poly(A)-Sepharose only after denaturation of the RNAs, indicating that the poly(U) was hydrogen bonded to the poly(A) at the 3'-terminus of the plus-strand RNA in these molecules. When treated with 0.02 mug of RNase A per ml, both RFs and RIs yielded the same distribution of the three cores, RFI, RFII, and RFIII. The minus-strand RNA of both RFI and RFIII contained a poly(U) sequence. That from RFII did not. It is known that RFI is the double-stranded form of the 42S plus-strand RNA and that RFIII is the experimetnally derived double-stranded form of 26S mRNA. The poly(A) sequences in each are most likely transcribed directly from the poly(U) at the 5'-end of the 42S minus-strand RNA. The 26S mRNA thus represents the nucleotide sequence in that one-third of the 42S plus-strand RNA that includes its 3'-terminus.
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PMID:Replication of semliki forest virus: polyadenylate in plus-strand RNA and polyuridylate in minus-strand RNA. 97 99

The present paper describes intracellular changes in ribonuclease specific activity during Ca2+-induced sporangium formation in the water mold Achyla bisexualis. The enzymes undergo a decrease in activity prior to crosswall formation followed by an increase in activity during spore cleavage. As spore discharge occurs the RNase activity again decreases. A large percentage of the nuclease activity is associated with a lysosomal-like fraction of the cell, but there is also considerably activity associated with nuclear and microsomal fractions. Addition of cycloheximide or actinomycin D at various times during development prevents further decrease or increase in the enzyme activity. Mixing of cell extracts from different developmental stages provides evidence that inhibitors or activators of the enzyme activity are not responsible for the activity levels evident at the different stages. There is a change in the total levels of presumptive mRNA during Ca2+-induced sporangial formation which appears to be associated with the patterns of RNase activity. Utilizing total cellular RNA and Poly(A)+ RNA with the crude ribonuclease preparations, no substrate specificity could be ascertained.
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PMID:The development patterns of lysosomal enzyme activities during Ca2+-induced sporangium formation in Achyla bisexualis. III. Ribonucleases. 98 98

The synthesis of poly(A)-containing RNA by isolated mitochondria from Ehrlich ascites cells was studied. Isolated mitochondria incorporate [3H]AMP or [3H]UTP into an RNA species that adsorbs on oligo (dT)-cellulose columns or Millipore filters. Hydrolysis of the poly(A)-containing RNA with pancreatic and T1 ribonucleases released a poly(A) sequence that had an electrophoretic mobility slightly faster than 4SE. In comparison, ascites-cell cytosolic poly(A)-containing RNA had a poly(A) tail that had an electrophoretic mobility of about 7SE. Sensitivity of the incorporation of [3H]AMP into poly(A)-containing RNA to ethidium bromide and to atractyloside and lack of sensitivity to immobilized ribonuclease added to the mitochondria after incubation indicated that the site of incorporation was mitochondrial. The poly(A)-containing RNA sedimented with a peak of about 18S, with much material of higher s value. After denaturation at 70 degrees C for 5 min the poly(A)-containing RNA separated into two components of 12S and 16S on a 5-20% (w/v) sucrose density gradient at 4 degrees C, or at 4 degrees and 25 degrees C in the presence of formaldehyde. Poly(A)-containing RNA synthesized in the presence of ethidium bromide sedimented at 5-10S in a 15-33% (w/v) sucrose density gradient at 24 degrees C. The poly(A) tail of this RNA was smaller than that synthesized in the absence of ethidium bromide. The size of the poly(A)-containing RNA (approx. 1300 nucleotides) is about the length necessary for that of mRNA species for the products of mitochondrial protein synthesis observed by ourselves and others.
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PMID:The synthesis of polyadenylic acid-containing ribonucleic acid by isolated mitochondria from Ehrlich ascites cells. 98 39

Purified rat liver mitochondria were shown to synthesize poly(adenylic acid) (poly(A)) in vitro. Detection of the poly(A) synthesizing activity was facilitated by addition of NaF to the reaction was shown to be poly(A) by its insensitivity to digestion with pancreatic RNase and RNase T1, its degradation by venom phosphodiesterase and its retention on poly (uridylic acid) 20-23 AMP units and it was covalently attached to the endogenous RNA in the mitochondria. Poly(A) synthesis required ATP and a divalent ion and was maximally active in the pH range of 7-8. The reaction was inhibited by atractyloside, cordycepin triphosphate, Rose Bengal, rifamycin derivative AF/103, sodium pyrophosphate, and N-ethylmaleimide. These studies indicate that the mitochondrial poly(A) polymerase previously described in our laboratory (Jacob, S.T., Rose, K.M., and Morris, H.P. (1974), Biochim. Biophys. Acta 361, 312-320) is involved in the posttranscriptional addition of poly(A) sequence to mitochondrial RNA.
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PMID:Poly(adenylic acid) synthesis in isolated rat liver mitochondria. 99 Feb 63

Messenger RNA (mRNA) of membrane-bound polysomes in a membrane fraction of WI-38 cells remains associated with the microsomal membranes even after ribosomes and their nascent polypeptide chains are removed by using puromycin in a high salt buffer or by disassembling the ribosomes in a medium of high ionic strength lacking magnesium. mRNA either was specifically labeled in the presence of actinomycin D, or it was recognized by virtue of its affinity for oligo-dT. Poly A segments in bound mRNAs have an electrophoretic mobility in acrylamide gels which is characteristic of cytoplasmic mRNAs and corresponds to 150-200 adenyl residues. Extensive RNase treatment did not lead to release of the poly A segments of membrane-associated mRNA molecules either from an intact membrane fraction or from a membrane fraction previously stripped of ribosomes. On the other hand, RNase treatment led to the release and digestion of the nonpoly A segments of the mRNA molecules, indicating that the site of attachment of mRNA to the ER membranes is located near or at the 3' end of the molecule which contains the poly A. A direct association of mRNAs and endoplasmic reticulum membranes is considered in a modelto explain the assembly of bound polysomes and protein synthesis in a membrane-associated apparatus.
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PMID:Direct association of messenger RNA with microsomal membranes in human diploid fibroblasts. 113 14

Poly(A)-containing RNA was isolated by cellulose column chromatography from total RNA extracted from Chlorella fusca var. vacuolata 211/8p. RNA retained by the column was identified as poly(A)-containing RNA because it contained ribonuclease-resistant tracts, 25 to 55 nucleotides in length, from which not less than 80% of base was found to be adenine after acid hydrolysis. The base composition of poly(A)-containing RNA differed from that of RNA (largely ribosomal) which did not adsorb to cellulose, having a higher adenine content and a lower guanine content. Poly(A)-containing RNA was polydisperse including molecules with mobilities from 10S to 40S with a mean of about 20S. In an in vitro system derived from wheat-germ, protein synthesis was stimulated by adding poly(A)-containing RNA from Chlorella. Optimum conditions were established in this system with respect to the amount of poly(A)-containing RNA added and the concentration of KCl and Mg-2+. It is proposed that, in Chlorella, poly(A)-containing RNA includes cytoplasmic mRNA as has been shown for some other eucaryotic organisms.
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PMID:Characterization and messenger activity of poly(A)-containing RNA from Chlorella. 115 44

The human hepatic asialoglycoprotein receptor comprises two homologous polypeptides designated H1 and H2. Two distinct complementary DNA clones encoding these receptor subunits have been previously isolated from the human hepatoblastoma cell line HepG2. We discovered that multiple variants of H2 transcripts exist both in HepG2 cells and in the normal human liver that, at least in part, appear to be the result of alternative splicing events. We have found that (a) the complementary DNA clone for H2 previously isolated from HepG2 cells, characterized by a 57-nucleotide insertion within the 5' end of the complementary DNA that is absent from H1, represented only one third of H2-related sequences in an unamplified normal human liver complementary DNA library and less than 10% of H2 clones in HepG2 cells; (b) the predominant message for H2 expressed in the liver and HepG2 cells, designated L-H2, appeared to represent the fully processed product of the gene encoding both L-H2 and H2; and (c) a variant H2 transcript existed in HepG2 cells, designated H2', that contained a novel, 5' 88-bp nucleotide insertion. Poly(A+) RNA analysis of the normal liver and HepG2 cells by complementary RNA hybridization and ribonuclease protection corroborated the observations made during the screening of complementary DNA libraries regarding the abundance of the various messages. A striking incongruity was found between the levels of messenger RNA containing the H2-specific 57-nucleotide sequence and the levels of polypeptide expressed in the liver and HepG2 cells as recognized by antiserum specifically raised against this sequence.
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PMID:Differences in the abundance of variably spliced transcripts for the second asialoglycoprotein receptor polypeptide, H2, in normal and transformed human liver. 137 82

Rapid decay of the c-fos transcript plays a critical role in controlling transforming potential of the c-fos proto-oncogene. One of the mRNA instability determinants is a 75-nucleotide AU-rich element (ARE) present in the 3' untranslated region of the c-fos transcript. It appears to control two steps in the process of c-fos mRNA degradation: removal of the poly(A) tail, which does not require the AUUUA motifs, and subsequent degradation of deadenylated mRNA, which appears to be dependent on the AUUUA motifs. In this study, we report the identification of four U-rich sequence binding proteins (URBPs) that specifically interact with a 20-nucleotide U-rich sequence within the c-fos ARE. Gel mobility shift assay and competition experiments showed that these protein factors form three specific band-shifted complexes with the c-fos ARE. Binding activity of one of the protein factors, a 37-kDa protein, is significantly affected by serum induction and by pretreatment of cells with drugs known to stabilize many of the immediate-early gene mRNAs. Combining UV cross-linking with a new approach, designated sequential RNase digestion, we were able to better determine the molecular masses of these cellular proteins. The binding sites for the four proteins were all mapped to a 20-nucleotide U-rich sequence located at the 3' half of the c-fos ARE, which contains no AUUUA pentanucleotides but stretches of uridylate residues. Single U-to-A point mutations in each of the three AUUUA motifs within the c-fos ARE have little effect on formation of the mobility-shifted complexes. Our data indicate c-fos ARE-protein interaction involves recognition of U stretches rather than recognition of the AUUUA motifs. We propose that UTBP binding may be involved in the first step, removal of the Poly(A) tail, in the c-fos ARE-mediated decay pathway.
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PMID:U-rich sequence-binding proteins (URBPs) interacting with a 20-nucleotide U-rich sequence in the 3' untranslated region of c-fos mRNA may be involved in the first step of c-fos mRNA degradation. 162 Jan 6

The cytoplasmic distribution of poly(A)+ mRNA and its relationship to annulate lamellae were examined in developing Necturus maculosus oocytes by in situ hybridization with [3H]poly(U). The specificity of [3H]poly(U) binding was tested by incubating control ovarian sections with either KOH or RNase A before in situ hybridization. In both experiments, the silver grain densities were markedly reduced. Poly(A)+ RNA is uniformly distributed in the cytoplasm until the mid-growth phase and then later in vitellogenesis becomes localized in the subcortical ooplasm. The silver grain density in the cytoplasm varied during oogenesis and was greatest in previtellogenic oocytes. Annulate lamellae commonly are observed with the light microscope in oocytes prior to vitellogenesis. In such oocytes, the labeled mRNA probe is observed over cytoplasmic regions of annulate lamellae. The results suggests that a differential localization of messenger RNA occurs during oogenesis in Necturus maculosus. Furthermore, poly(A)+ RNA is present in cytoplasmic regions of annulate lamellae.
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PMID:Cytoplasmic distribution of poly(A)-containing RNA in developing Necturus maculosus oocytes with reference to annulate lamellae. 171 57


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