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Query: EC:2.7.7.6 (RNA polymerase)
 34,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The dependence of chromatin conformation upon salt concentration has been studied for chicken ovalbumin and beta-globin genes isolated from oviduct and adult erythrocytes. At NaCl concentrations of 25 or 50 mM, the sedimentation properties, as a function of DNA size, of ovalbumin and globin chromatin are similar regardless of the source of the chromatin. In 100 mM NaCl, however, beta-globin chromatin isolated from erythrocytes sediments more slowly than an ovalbumin chromatin fraction from erythrocytes containing DNA of the same size. When the same experiment is carried out with material isolated from oviduct nuclei, the relative sedimentation rates are reversed, so that the ovalbumin chromatin sediments more slowly. This behavior cannot be accounted for by differences in binding of RNA polymerase or other molecules associated with transcription, or by partial aggregation of the chromatin. The most reasonable explanation is that transcriptionally active chromatin with a history of transcriptional activity, although largely covered with histones and capable of considerable compaction, is not able to form a fully compact structure as the ionic strength is raised. This behavior is consistent with a slight depletion in active chromatin of core histones or histone H1/H5 or both.
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PMID:Comparison of the folding of beta-globin and ovalbumin gene containing chromatin isolated from chicken oviduct and erythrocytes. 380 55

These studies examine the effect of ribavirin triphosphate (RTP) on two replicative functions associated with influenza virus nucleocapsids, primer generation and its subsequent elongation. To study primer generation influenza virus cores were added to beta-globin mRNA in the presence of only [32P]GTP. To examine elongation, ATP and CTP were added to the reaction mixture to permit limited elongation, and products from both reactions were separated on polyacrylamide gels and quantified. Under these conditions, the 50% inhibitory concentration of RTP for primer generation was 3.0 mM, and the 50% inhibitory concentration for elongation was 0.6 mM. RNA polymerase activity associated with cores isolated from clinical strains of influenza A and B viruses reacted as did the laboratory strain of influenza virus and was equally susceptible to inhibition by RTP.
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PMID:Effect of ribavirin triphosphate on primer generation and elongation during influenza virus transcription in vitro. 398 7

Globin messenger RNA, isolated from human peripheral blood reticulocytes, was transcribed into complementary DNA by use of the RNA-dependent DNA polymerase of avian myeloblastosis virus. The complementary DNA was then transcribed into (32)P-labeled complementary RNA by E. coli RNA polymerase in the presence of alpha-(32)P-labeled ribonucleoside triphosphates. The fingerprint pattern obtained from ribonuclease T1 digests of human globin complementary RNA was specific and reproducible. Different patterns were obtained from digests of duck, mouse, and rabbit globin complementary RNA. The fingerprint patterns obtained from digests of purified natural human 10S globin messenger RNA, labeled in vitro with (125)I or with [gamma-(32)P]ATP and polynucleotide kinase, were similar to that of the complementary RNA but contained some additional oligonucleotides. Sufficient nucleotide sequence information has been obtained from about 50% of the intermediate sized oligonucleotides (8-14 base residues long), to make possible examination of correspondence between these nucleotide sequences and globin amino-acid sequences. Approximately 70% of these oligonucleotide sequences can be matched to unique amino-acid sequences in the alpha- or beta-globin chains. The other 30% do not match known amino-acid sequences and presumably correspond to untranslated portions of the mRNA; some of these sequences, however, can be matched to amino-acid sequence in the abnormally long segment of the alpha chain of hemoglobin Constant Spring, which is thought to result from a chain-termination mutation.
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PMID:Nucleotide sequences of human globin messenger RNA. 413 9

A new fractionation procedure separates a whole-cell HeLa extract into three components required for accurate in vitro transcription. One component (Sp1) is a promoter-specific factor required for transcription of the SV40 early and late promoters, but not for transcription of other promoters we have tested. The second component (Sp2) is a general factor required for transcription of the SV40 promoters and a series of others, including the adeno-virus 2 major late promoter, the human beta-globin promoter and the avian sarcoma virus promoter. The third component is a fraction containing the endogenous RNA polymerase II. When SV40 and adenovirus templates were present simultaneously in an in vitro transcription reaction, addition of the Sp1 factor stimulated SV40 early promoter transcription 40-fold, and inhibited adenovirus major late promoter transcription by 40%. This finding suggests that Sp1 is involved in promoter selection, and is not merely a general transcription stimulatory factor.
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PMID:Isolation of transcription factors that discriminate between different promoters recognized by RNA polymerase II. 618 69

The ability of purified U1 small nuclear RNA-protein complexes (U1 snRNPs) to bind in vitro to two RNAs transcribed from recombinant DNA clones by bacteriophage T7 RNA polymerase has been studied. A transcript which contains sequences corresponding to the small intron and flanking exons of the major mouse beta-globin gene is bound in marked preference to an RNA devoid of splice site sequences. The site of U1 snRNP binding to the globin RNA has been defined by T1 ribonuclease digestion of the RNA-U1 snRNP complex. A 15-17-nucleotide region, including the 5' splice site, remains undigested and complexed with the snRNP such that it can be co-precipitated by antibodies directed against the U1 snRNP. Partial proteinase K digestion of the U1 snRNP abolishes interaction with the globin RNA, indicating that the snRNP proteins contribute significantly to RNA binding. No RNA cleavage, splicing, or recognition of the 3' splice site by U1 snRNPs has been detected. Our results are discussed in terms of the probable role of U1 snRNPs in the messenger RNA splicing of eucaryotic cell nuclei.
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PMID:The U1 small nuclear RNA-protein complex selectively binds a 5' splice site in vitro. 619 May 73

We have investigated low abundance RNAs transcribed in vitro and in vivo from the human beta-globin gene. These RNAs contain globin mRNA sequences covalently linked to sequences transcribed from the 5' flanking region between -235 and the mRNA cap site (+1). Their synthesis in vitro is sensitive to high (100 micrograms/ml) levels of alpha-amanitin but not to low (2 micrograms/ml) levels, and one region of the DNA template bordering their 5' termini is similar to a small segment of Alu repetitive DNA and to the RNA polymerase III promoter consensus sequence. Therefore, these RNAs are transcribed by RNA polymerase III but extend into the mRNA-coding region that is usually transcribed by polymerase II. The polymerase III transcripts are polyadenylated and are probably spliced. Their presence in bone marrow cells and peripheral blood reticulocytes implies that they play some role in the erythroid cell.
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PMID:Human beta-globin promoter and coding sequences transcribed by RNA polymerase III. 619 93

Nuclei were prepared from mature and immature hen erythrocytes and incubated for RNA synthesis in the absence or in the presence of Sarkosyl. The in vitro labelled synthesized RNA was hybridized to specific 5' and 3' fragments of the chicken adult beta-globin gene to investigate the possible presence of RNA polymerase molecules bound to this gene in the form of transcriptional complexes. Surprisingly, such RNA polymerase B molecules were found located preferentially in the 5' end moiety of the beta-globin genes of mature erythrocytes, although they are apparently evenly distributed along the beta-globin genes of immature polychromatic erythrocytes. The significance of these observations with respect to (1) preferential DNaseI sensitivity of "genes which have been transcribed" and (2) control of transcription in eukaryotic cells is discussed.
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PMID:Clustering of RNA polymerase B molecules in the 5' moiety of the adult beta-globin gene of hen erythrocytes. 626 56

We have determined the nucleotide sequence of an embryonic beta-globin gene of the Balb/c mouse. It possesses structural features typical of known expressed beta-globins, including 5'-untranslated region, potential capping site, initiation and terminator codons, poly(A) addition signal, splicing signals, and intervening sequences. There is a striking 15-base homology between the putative RNA polymerase binding site of this gene and the corresponding region of a human embryonic beta-gene which may be important in the control of expression during embryonic development. The sequence of the gene predicts the sequence of the entire y2 protein, which has not previously been available. As expected from evolutionary considerations, it is more homologous to human embryonic beta-globin than to mouse adult beta-globin.
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PMID:The sequence of a mouse embryonic beta-globin gene. Evolution of the gene and its signal region. 627 52

Since the initial discovery that the DNase I sensitivity of the globin genes in different cell types correlates with globin gene expression, this relationship has been shown to hold true for a variety of genes, including the genes for ovalbumin, conalbumun, alpha- and beta-globin in chicken, several heat-shock proteins in Drosophila, the r-chromatin of Tetrahymena and the viral polyoma minichromosome. Although genes transcribed by RNA polymerases I and II have been studied extensively, the genes transcribed by RNA polymerase III have not. We have therefore investigated the DNase I sensitivity of transfer RNA (tRNA) and oogenetic 5S RNA genes in the liver and erythocyte nuclei of Xenopus laevis. The oogenetic 5S genes are not transcribed in any known somatic cell, and tRNA genes are transcribed in the hepatocyte but are inactive in the erythrocyte. We show here that, although in these two cell types the correspondence between DNase I sensitivity and gene transcription holds good for globin and the ribosomal genes, the tRNA and oogenetic 5S genes are DNase I sensitive in both liver and erythrocyte nuclei. Thus for the genes transcribed by polymerase III the correspondence of sensitivity and expression breaks down.
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PMID:The DNase I sensitivity of Xenopus laevis genes transcribed by RNA polymerase III. 628

Chick embryo red blood cells express the embryonic globin and the rRNA genes before 5 days of development but only the adult globin genes and no rRNA after 12 days of development. We have isolated nuclei from the red blood cells of these developmental stages and allowed them to transcribe in vitro. We have analyzed the overall transcriptional properties of these nuclei, the overall activities of RNA polymerases I and II and the sequence-specific activity of RNA polymerase II in the beta-globin domain using cloned genomic hybridization probes. Among our findings are the following. 1) Erythroid nuclei of 5-day embryos are more transcriptionally active than those at 12 days. 2) RNA polymerase I is a very active at 5 days but is off by 12 days. 3) A template-independent activity which yields labeled RNA is present in the red cell nuclei of 12-day but not 5-day embryos. 4) Between 5 and 12 days of development transcriptional modulation delineates embryonic and adult beta-globin domains. 5) These domains exceed the boundaries of the genes themselves by several kilobases. 6) All transcripts which hybridize to sequences in the beta-globin gene region, including repeat sequence transcripts, are transcribed by RNA polymerase II.
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PMID:Transcriptional properties of chick embryonic erythroid nuclei in vitro. 628 78


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