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

We examined the structure of the promoter for the human U2 snRNA gene, a strong RNA polymerase II transcription unit without an obvious TATA box. A set of 5' deletions was constructed and assayed for the ability to direct initiation of U2 snRNA after microinjection into Xenopus oocytes. Sequences between positions -295 and -218 contain an activator element which stimulates accurate initiation by 20- to 50-fold, although as few as 62 base pairs of 5' flanking sequence are sufficient to direct the accurate initiation of U2 RNA. When the activator was recloned in the proper orientation at either of two different upstream locations, the use of the normal U2 start site was stimulated. Inversion of the element destroyed the stimulation of accurate U2 initiation, but initiation at aberrant upstream start sites was enhanced by the element in both orientations. A 4-base-pair deletion that destroyed the activity of the element lies within a sequence (region III) which is highly conserved among U2 genes from different organisms. Mutations in the activator also affected the ability of the U2 template to compete with a wild-type U1 gene in coinjection experiments. We propose that the element enhances the efficiency of transcription in part by facilitating the association of a limiting factor with transcription complexes. Human U1 snRNA genes possess a region homologous to U2 region III, and we suggest that upstream activator elements may be a general feature of snRNA promoters.
Mol Cell Biol 1985 Jul
PMID:Orientation-dependent transcriptional activator upstream of a human U2 snRNA gene. 241 Jul 71

In vitro transcription in a HeLa cell lysate by RNA polymerase II directed by a chicken feather keratin gene promotor has been studied using unmethylated template DNA and DNA methylated in vitro by HpaII methylase. The efficiency of specific gene transcription from methylated DNA was dependent on topology of the input DNA, the most significant effect being complete inhibition of transcription from one template which contained three methylation sites, one just 5' and two greater than 500 bases 3' to the site of transcription initiation. The inhibition of transcription depends on a factor(s) which is variably present in lysate preparations and is labile on storage at -70 degrees.
Mol Biol Rep 1986
PMID:Effects of DNA methylation on specific transcription by RNA polymerase II in vitro. 241 49

Cloned human rRNA gene fragments that included the promoter region were introduced into Chinese hamster dihydrofolate reductase-deficient (dhfr-) cells by cotransformation with a dhfr minigene and amplified by selection for methotrexate resistance. The human ribosomal DNA was transcribed by RNA polymerase II, not RNA polymerase I or III. The metaphase chromosome regions containing the transcriptionally active human ribosomal DNA failed to show silver staining.
Mol Cell Biol 1987 Mar
PMID:Human ribosomal DNA fragments amplified in hamster cells are transcribed only by RNA polymerase II and are not silver stained. 243 41

The template-engaged RNA polymerase II was assayed in the nuclei purified from the cerebral hemisphere of 3-, 14- and 30-day old rats. Its activity is the highest at 3-day and declines as development proceeds. Lower transcription at 30-day may either be due to a decrease in the active fraction of chromatin or to a decrease in the amount of RNA polymerase II that is active towards endogenous template, or both. The activity of RNA polymerase I (active in low salt) is also maximal at 3-day and declines as development proceeds. (ADP)ribosylation of chromatin depresses RNA synthesis. This may be due to inactivation of RNA polymerase itself by protein poly(ADP)ribosylation.
Mol Biol Rep 1987
PMID:Effect of in vitro (ADP)ribosylation on transcription of the chromatin of the brain of developing rats. 244 99

Purified anti-topoisomerase I immunoglobulin G (IgG) was microinjected into nuclei of Chironomus tentans salivary gland cells, and the effect on DNA transcription was investigated. Synthesis of nucleolar preribosomal 38S RNA by RNA polymerase I and of chromosomal Balbiani ring RNA by RNA polymerase II was inhibited by about 80%. The inhibitory action of anti-topoisomerase I IgG could be reversed by the addition of exogenous topoisomerase I. Anti-topoisomerase I IgG had less effect on RNA polymerase II-promoted activity of other less efficiently transcribing heterogeneous nuclear RNA genes. The pattern of inhibition of growing nascent Balbiani ring chains indicated that the transcriptional process was interrupted at the level of chain elongation. The highly decondensed state of active Balbiani ring chromatin, however, remained unaffected after injection of topoisomerase I antibodies. These data are consistent with the interpretation that topoisomerase I is an essential component in the transcriptional process but not in the maintenance of the decondensed state of active chromatin.
Mol Cell Biol 1987 Dec
PMID:Microinjection of anti-topoisomerase I immunoglobulin G into nuclei of Chironomus tentans salivary gland cells leads to blockage of transcription elongation. 244 4

We have further characterized a temperature-sensitive mutant of Chinese hamster lung fibroblasts in tissue culture with a defect in RNA metabolism. The mutant phenotype is reflected in transcription in crude extracts or in isolated nuclei, when these are made from cells shifted to the nonpermissive temperature; however, differential heat inactivation between mutant and wild-type extracts cannot be demonstrated with cell-free systems. We tentatively conclude that the mutation may affect initiation of transcription which cannot be observed in our in vitro systems. Partially purified RNA polymerase I, II, and III fractions are indistinguishable from wild type. A temperature shift does not affect transcription by RNA polymerase III measured with intact cells or by nuclear run-on experiments. The nuclear run-on and other experiments suggest that RNA polymerase II-dependent transcription is inhibited before RNA polymerase I-dependent transcription. This conclusion is also supported by Northern analyses of selected mRNAs in nonsynchronized and synchronized cells after a shift to the nonpermissive temperature.
Somat Cell Mol Genet 1988 Sep
PMID:Steady-state and nuclear run-on analyses of transcription in a temperature-sensitive Chinese hamster cell mutant with a defect in RNA metabolism. 245 82

Methyl mercury (MeHg) inhibited the overall RNA synthetic reaction of HeLa RNA polymerase II. However, when RNA chain initiation was allowed to occur in its absence, MeHg stimulated the rate of the subsequent elongation stage of the reaction. Chain elongation with both double-stranded and single-stranded DNA templates was stimulated. This stimulatory effect was specific for MeHg; both p-hydroxymercuribenzoate and HgCl2 inhibited chain elongation (to about the same degree as they inhibited the overall reaction). The stimulatory effect was also specific for the HeLa polymerase; with Escherichia coli RNA polymerase, MeHg inhibited elongation (to the same degree as it inhibited the overall reaction).
Mol Pharmacol 1988 Nov
PMID:Methyl mercury stimulates chain elongation by purified HeLa RNA polymerase II. 246 8

We have previously shown that assembly of nucleosomes on the DNA template blocks transcription initiation by RNA polymerase II in vitro. In the studies reported here, we demonstrate that assembly of a complete RNA polymerase II preinitiation complex before nucleosome assembly results in nucleosomal templates which support initiation in vitro as efficiently as naked DNA. Control experiments prove that our observations are not the result of slow displacement of nucleosomes by the transcription machinery during chromatin assembly, nor are they an artifact of inefficient nucleosome deposition on templates already bearing an RNA polymerase. Thus, the RNA polymerase II preinitiation complex appears to be resistant to disruption by subsequent nucleosome assembly.
Mol Cell Biol 1988 Aug
PMID:Assembly of RNA polymerase II preinitiation complexes before assembly of nucleosomes allows efficient initiation of transcription on nucleosomal templates. 246 72

Elongation and termination by RNA polymerase II are important regulatory steps for eukaryotic gene expression. We have previously studied the transcription of linear DNA templates where specific initiation of transcription by highly purified RNA polymerase II can be achieved in the absence of promoters and promoter-specific factors. Using these templates we have shown that a human histone gene, H3.3, contains sequences (intrinsic terminators) within which purified RNA polymerase II will efficiently terminate transcription (Reines, D., Wells, D., Chamberlin, M.J., and Kane, C. M. (1987) J. Mol. Biol. 196, 299-312). Curiously, these signals were found within an intron, 3'-untranslated, and protein-encoding regions of the gene suggesting that they might act to attenuate transcription of H3.3 in vivo. Here we show that intrinsic terminator sequences from an H3.3 gene intron also block in vitro transcript elongation by RNA polymerase II when the enzyme has initiated transcription from a promoter using highly purified transcription initiation factors. However, under the conditions used for promoter-specific transcription there is little transcript release. Instead the polymerase can pause at these sites for periods exceeding 60 min. We have identified and partially purified an activity from HeLa cells that causes the transcription complex to read through this block to transcription elongation. This readthrough activity fractionates with a previously characterized elongation factor (SII) over three chromatographic columns. A homogeneous preparation of calf thymus SII can also provide this activity in trans. This factor may facilitate passage of the RNA polymerase II transcription complex through such intragenic sites in cellular genes in vivo.
 ...
PMID:Transcription elongation factor SII (TFIIS) enables RNA polymerase II to elongate through a block to transcription in a human gene in vitro. 247 7

We have cloned and sequenced the gene coding for the second-largest subunit of RNA polymerase III of Drosophila melanogaster (DmRP135). The gene, interrupted by two introns of 62 and 59 bp, respectively, codes for an mRNA of 3.6 kb. As for other housekeeping genes transcription initiates at several sites (between positions -98 and -76) none of which is preceded by a clear TATA sequence. The deduced polypeptide consists of 1129 amino acids with an aggregate molecular weight of 128 kDa. The protein sequence features the same regions of similarity as observed for the corresponding subunits of RNA polymerase II of Drosophila and yeast and the Escherichia coli beta subunit. As in the second-largest subunit of RNA polymerase II there is a zinc-binding motif which is absent in the beta subunit of E. coli. Antibodies directed against a fusion protein expressing 164 amino acids of the DmRP135 polypeptide cross-react with the second-largest subunit of RNA polymerase III of yeast and generate a distinct banding pattern on Drosophila polytene chromosomes distinguishable from that obtained with anti-RNA polymerase II antibodies.
Mol Gen Genet 1989 Nov
PMID:Primary structure and functional aspects of the gene coding for the second-largest subunit of RNA polymerase III of Drosophila. 248 32


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