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:3.1.27.1 (RNase)
16,360 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Five ribonuclease activities, separable by polyacrylamide gel electrophoresis, have been detected in erythroid bone marrow cells from anaemic rabbits. Their intracellular distribution has been investigated and compared with that of the ribonucleases in reticulocytes. Both the acid and alkaline ribonuclease activities of reticulocytes are much lower (30--50 fold) than those of bone marrow erythroid cells. The most marked decrease in enzyme activity occurs in the fractions containing ribosomes and mitochondria plus lysosomes. In these subcellular organelles there was also a qualitative change in the ribonuclease electrophoretic pattern, whereas the cytosol enzymes of marrow erythroid cells and reticulocytes remained largely unchanged. Several ribonucleases released from reticulocyte membranes with urea were similar to those present in the lysosomal plus mitochondrial fraction, as shown by detection of enzyme activity after polyacrylamide gel electrophoresis. The decline in ribonuclease activity was found to begin in the orthochromatic cells, which have a highly condensed nucleus and are no longer active in DNA and RNA synthesis, and to coincide with a decrease in acid phosphatase activity and loss of lysosomes.
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PMID:Intracellular distribution of ribonuclease activity during erythroid cell development. 1 51

Precursor mRNA (pre-mRNA) was extracted from erythroid enriched bone marrow cells of the rabbit by the methods of Georgiev and Mantieva modified by Markov and Arion and of Holmes and Bonner, respectively. Density gradient centrifugation, base analysis and the effects of alpha-amanitin and actinomycin D on the synthesis of the cellular RNA showed signs of degradation in the rRNA-free 85 degrees C-fraction of the preparation according to Georgiev and Mantieva and a substantial rRNA contamination of the 65 degrees C-fraction. This RNA-fraction as well as the total RNA-preparation extracted according to Holmes and Bonner was purified from rRNA by affinity chromatography on poly(U)-Sepharose. Poly(A)+-RNA of all size-classes, among it a substantial amount of high molecular weight RNA (greater than 45 S), was isolated by this purification procedure. Especially the extraction according to Holmes and Bonner yields high molecular weight material but the critical step of this procedure often resulting in degradation of the RNA is the DNase treatment of the heavily DNA-contaminated total RNA-preparation either due to RNase contamination of the DNase or to the existence of RNase in the less intensive deproteinized RNA. The investigated cellular system is characterized by a very intensive rRNA synthesis which is typical for cells in the early stages of hematopoiesis. In contrast to investigations with purified RNA-polymerases and subcellular systems, but in accordance with data of in vivo experiments, alpha-amanitin inhibits both the pre-mRNA and the pre-rRNA synthesis.
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PMID:Pre-mRNA from erythroid enriched bone marrow cells of the rabbit. II. Characterization of pre-mRNA isolated by phenol extraction and poly(U)-Sepharose chromatography. 74 68

Pre-mRNA from bone marrow of rabbits enriched in erythroid cells was analyzed by T1 and pancreatic RNase treatment and poly(U)- and poly(A)-Sepharose chromatography to contain poly(A)-, oligo(U)- and double stranded sequences. The length of the poly(A)- and oligo(U)-sequences was determined by polyacrylamide gel electrophoresis using poly(A)- and oligo(U)-standards of defined length. Poly(A) from poly(A)+pre-mRNA isolated according to the method of Holmes and Bonner shows a size distribution between 40 and 130 nucleotides with an average of 75 nucleotides. Hot phenol extraction according to Georgiev et al. leads to a smaller size of about 25 nucleotides. The oligo(U)-segment consists of 80% U and is about 25 nucleotides long. Poly(A)+ pre-mRNA of about 12000--16000 nucleotides posseses 1--2 oligo(U)-units and one double strand of about 70 nucleotide pairs. Most (greater than 90%) of the oligo(U)-and the double stranded sequences are localized at least 1700 nucleotides away from the 3'terminus. Double strands were investigated with respect to their reannealing behaviour. The material consists of two types of double strands: 20% which reassociate at a cot/2 cot/2 of 1.3 . 10(-4) represent only one or a few types of double strands, the remaining 80% reassociate at a cot/2 of about 7 . 10(-2) and are more complex. Under hybridization conditions pre-mRNA molecules are able to self-annealation. 10% of the sequences become RNase stable.
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PMID:Pre-mRNA from erythroid enriched bone marrow cells of the rabbit. III. Poly(A)-, oligo(U)- and double stranded sequences. 74 69

Poly(A)-containing mRNAs labeled with [methyl-3H]methionine were isolated from nucleated erythroid cells obtained from the spleens of anemic mice. The RNAs were further separated into non-globin poly(A)-containing RNAs and highly purified globin mRNA by globin cDNA-cellulose affinity chromatography. DEAE-Sephadex column chromatography of the T2 ribonuclease digestion products of the cDNA-purified globin mRNA fraction yielded methylated resistant fragments with charges of -4.7 (Cap 1) and -5.3 (Cap 2). Digestion of the non-globin RNA fraction revealed a similar pattern with the addition of a methylated mononucleotide identified as 6-methyladenosine at -2 charges. Alkaline phosphatase treatment of the T2 resistant fragments reduced their charges by approximately 2, which is consistent with the removal of one terminal phosphate. Treatment of the globin T2 and alkaline phosphatase-resistant fragments withpenicillium P1 nuclease and alkaline phosphatase yielded a P1-resistant core structure in both fragments. In addition to the core, 2'-O-methylcytidine (Cm) was released from the more negatively charged globin fragment. The P1-resistant cores of the cap structures eluted from DEAE-Sephadex with the known standard m2G5'ppp5'Am and were found to be pyrophosphatase-sensitive establishing a 5'-5'-triphosphate linkage. The pyrophosphatase and alkaline phosphatase digestion products of the globin Cap 1 and Cap 2 core structures were analyzed by high voltage electrophoresis and paper chromatography and found to be 7-methyiguanosine (m7G) and the dimethylated nucleoside 6-methyl-2'-O-methyladenosine (N6mAm). A small amount of the singularly methylated adenosine, 2'-O-methyladenosine (Am) was also observed. The predominant sequences of the methylated nucleosides in the globin cap structures are therefore m7G5'ppp5'N6mAm and m7G5'ppp5'N6mAmpCm.
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PMID:Methylated nucleosides in globin mRNA from mouse nucleated erythroid cells. 83 41

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 size of the polyadenylate segment of globin messenger RNA isolated from spleens of anaemic rabbits was estimated by comparison of its electrophoretic migration in polyacrylamide gels to that of synthetic poly(A) segments of known lengths. Conditions of enzymic degradation of mRNA with pancreatic ribonuclease and T1 ribonuclease were carefully established in order to ensure complete degradation of the heteropolymeric part of mRNA without affecting the polyadenylate sequence. The poly (A) segments of spleen globin mRNA were found to be 25-90 nucleotides long whilst those of peripheral blood reticulocytes from the same animals were only 10-30 residues long. Since spleen contains young erythroid cells and since anucleated blood reticulocytes constitute a statistically older population of the same cell line, these results support the idea that the poly(A) segment of mRNA shortens when the message ages.
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PMID:Globin messenger RNA from anaemic rabbit spleen. Size of its polyadenylate segment. 97 66

The Friend leukemia virus (FLV)-infected cell line, T-3-Cl-2, undergoes a form of erythroid differentiation in culture when treated with an appropriate inducer, such as dimethylsulfoxide ((CH3)2SO). Thus, whereas untreated cells contain no detectable hemoglobin, treated cells accumulate hemoglobin in quantities comparable to those in the mature mouse red blood cell. We have investigated the mechanism of hemoglobin induction by quantitating the number of globin genes and the amount of globin mRNA in cells before and during the period of hemoglobin accumulation. The results indicate the number of globin genes does not change as the cells accumulate hemogtobin: There are less than 5 globin genes per haploid genome. On the other hand, whereas cells lacking hemoglobin contain little, if any, globin mRNA, hemoglobin-containing cells accumulate, on the average, 8,000 molecules of globin mRNA per cell. The most direct, although, by no means, the only interpretation of these results is that the induction of hemoglobin synthesis involves transcriptional activation of the globin genes. Using this same cell line, we show that mouse globin mRNA sequences are also present in viral particles purified from the culture medium of globin-producing cells. These globin mRNA sequences are absent from viral particles derived from T-3-Cl-2 cells which are not producing globin mRNA. Virus-associated globin mRNA sequences sediment in association with 60S viral RNA complex as well as in free, 9S form. However, under mild denaturing conditions which result in the conversion of viral 60 S RNA to 30S and smaller forms, all the globin sequences sediment as 9S RNA. Appropriate control experiments indicate that the virus-associated globin mRNA is resistant to degradation by exogenous ribonuclease; that exogenously added globin mRNA does not become associated with the 60S viral RNA complex; and that globin mRNA can be detected in virions derived from cells both induced for and constitutively synthesizing globin mRNA. The presence of globin mRNA sequences in FLV particles has important implications in terms of our ability to distinguish between host and viral RNAs in viral particles and in terms of the possible role RNA tumor viruses might play in transduction of genetic information.
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PMID:Induction of globin mRNA in Friend leukemia virus-infected cells and its presence in viral 60S RNA. 117 37

Erythropoiesis in vertebrates is characterized by sequential changes in erythropoietic site, erythroblast morphology, and hemoglobin synthesis. We have examined the expression of globin chains and the major erythroid transcription factor GATA-1 (previously known as GF-1/NF-E1/Eryf 1) from days 7.5 to 17.5 of mouse development. mRNAs for embryonic (epsilon y2, beta H1, and zeta) and adult (alpha and beta) globin chains were quantitated by RNase protection assays. Switching of globins within the alpha-globin cluster (alpha and zeta) was not strictly coordinated with that within the beta-globin cluster (epsilon y2, beta H1, and beta). Regulation of globin switches during development was primarily transcriptional. Of particular note, we found two developmental switches (beta H1 to epsilon y2 and epsilon y2 to beta) in the mouse, more analogous than previously thought to shifts found in human development. The erythroid transcription factor GATA-1, believed to be a principal regulator of genes expressed in erythroid cells, first appeared in the embryo in yolk sac at the time of blood island formation and remained at a low level during embryonic erythropoiesis (8 to 11 days) relative to that found later in fetal liver (12 to 15 days). The rise in GATA-1 mRNA in fetal liver paralleled and preceded the rapid accumulation of adult beta-globin RNA. RNase protection assays and a GATA-1-specific peptide antiserum were used to establish that a single GATA-1 polypeptide is expressed throughout mouse development. Overall, these findings suggest that the levels of this erythroid transcription factor during development may contribute to the differential gene activation characteristic of definitive versus primitive erythropoiesis.
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PMID:Regulated expression of globin chains and the erythroid transcription factor GATA-1 during erythropoiesis in the developing mouse. 170 Oct 19

Regulation of the expression of the erythropoietin (Epo) receptor (EpoR) gene is under the control of transcriptional regulatory factor GATA-1. GATA-1 is expressed widely among the nonerythroid, factor-dependent subclones of the interleukin 3-dependent mouse cell line 32D. Consequently, to determine whether GATA-1 and EpoR gene expression are linked even in nonerythroid cells, we have studied the correlation of GATA-1 expression with expression and function of EpoR in these cell lines. EpoR mRNA (by RNase protection analysis) and EpoR protein (by specific antibody immunoprecipitation of metabolically labeled EpoR protein) were detectable not only in 32D and 32D Epo (an Epo-dependent subclone) but also in 32D GM, a subclone dependent for growth on granulocyte/macrophage colony-stimulating factor. EpoR mRNA also was detectable by PCR in 32D G, a subclone dependent for growth on granulocyte colony-stimulating factor. However, only 32D Epo cells bound 125I-labeled Epo and expressed EpoR protein on the cell surface, as determined by immunoprecipitation of surface-labeled proteins. These results indicate that, in these factor-dependent cell lines, the major regulatory step determining the erythroid-specific response to Epo is the efficiency of EpoR protein translocation to the cell surface. Mechanisms that could affect lineage-specific translocation are the presence of a chaperone protein, erythroid-specific editing of EpoR mRNA, or altered processing of the EpoR protein to the cell surface. In this model, lineage-restricted responses to growth factors such as Epo are determined not by expression of the genes for growth factor receptors but, rather, by appropriate processing of the receptor protein.
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PMID:Response to erythropoietin in erythroid subclones of the factor-dependent cell line 32D is determined by translocation of the erythropoietin receptor to the cell surface. 172 18

In order to investigate the pathogenesis of renal anemia, erythroid marrow cellularity, factors affecting erythropoiesis and hemolysis, hemolysis starting point by Parpart method and red cell life-span were studied in 21 patients undergoing hemodialysis (HD). Mean value of serum erythropoietin level (EPO) in HD patients was 28.4 mU/ml, which value was nearly equal to that in healthy subjects. Total erythroblast count was higher than normal up to 25.2% in HD patients with Ht below 25% (A group), on the other hand, in HD patients with Ht above 25% (B group) it was 21 6%, nearly equal to normal. Total erythroblast counts positively correlated to EPO level, but did not correlate to ribonuclease, aluminium and parathyroid hormone. Red cell life-span was 23.4 days in A group, and it was 19.8 days in B group Hemolysis starting point was observed at 0.61% NaCl in B group, and at 0.56% in A group. Hemolysis starting point negatively correlated to red cell life-span, but did not correlate to BUN, serum creatinine and serum guanidino compound. Hb level negatively correlated to nuclear cell counts of bone marrow in HD patients, and positively correlated to hemolysis starting point. These results suggested that erythroblast count was controlled by both erythropoietin and hemoglobin levels in HD patients. Hemoglobin level in HD patients was maintained by balance of counteracting factors between erythropoiesis and hemolysis.
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PMID:[Erythropoiesis and hemolysis in hemodialysis patients]. 258 29


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