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

Steroid receptors have been reported to stimulate transcription in a manner synergistic with other transcription factors. We have examined this synergism or functional cooperativity between glucocorticoid receptors and basal transcription factors in a variety of promoter and reporter gene contexts. A fragment containing a hormone response element from mouse mammary tumor virus was fused to well characterized promoters from the herpes virus thymidine kinase and mouse beta-globin genes and to related mutant promoters altered by inactivation of transcription factor-binding sites through point mutagenesis or deletion. These constructs were transfected into glucocorticoid-sensitive fibroblasts, and reporter gene activity was assessed with or without hormonal stimulation. In contrast to previous studies, we found little indication of synergistic interaction between elements mediating a hormone response and adjacent basal promoters. In fact, we observed that inactivating basal factor-binding sites, thereby decreasing promoter strength, actually increased hormone inducibility. We suggest that the inverse relationship between basal promoter strength and the induction ratio attained upon hormonal stimulation may be due to limitation of a common factor, an "adaptor" through which glucocorticoid receptor and basal transcription factors interact with the components of the RNA polymerase II complex to stimulate rates of transcription.
Mol Endocrinol 1991 May
PMID:Concerted stimulation of transcription by glucocorticoid receptors and basal transcription factors: limited transcriptional synergism suggests mediation by coactivators/adaptors. 207 21

We have cloned and sequenced the gene encoding the largest subunit of RNA polymerase II (RPB1) from Arabidopsis thaliana and partially sequenced genes from soybean (Glycine max). We have also determined the nucleotide sequence for a number of cDNA clones which encode the carboxyl terminal domains (CTDs) of RNA polymerase II from both soybean and Arabidopsis. The Arabidopsis RPB1 gene encodes a polypeptide of approximately 205 kDa, consists of 12 exons, and encompasses more than 8 kb. Predicted amino acid sequence shows eight regions of similarity with the largest subunit of other prokaryotic and eukaryotic RNA polymerases, as well as a highly conserved CTD unique to RNA polymerase II. The CTDs in plants, like those in most other eukaryotes, consist of tandem heptapeptide repeats with the consensus amino acid sequence PTSPSYS. The portion of RPB1 which encodes the CTD in plants differs from that of RPB1 of animals and lower eukaryotes. All the plant genes examined contain 2-3 introns within the CTD encoding regions, and at least two plant genes contain an alternatively spliced intron in the 3' untranslated region. Several clustered amino acid substitutions in the CTD are conserved in the two plant species examined, but are not found in other eukaryotes. RPB1 is encoded by a multigene family in soybean, but a single gene encodes this subunit in Arabidopsis and most other eukaryotes.
Plant Mol Biol 1990 Aug
PMID:Analysis of the genes encoding the largest subunit of RNA polymerase II in Arabidopsis and soybean. 210 47

When B cells encounter antigen, the cells mature into terminally differentiated plasma cells and the amount of steady-state immunoglobulin (Ig) mu mRNA is increased 23-60-fold over the amount seen in earlier B cell stages. Most of this dramatic increase in Ig gene mRNA accumulation could be due to post-transcriptional regulation. We have treated a series of mouse cell lines fixed at different stages of B cell differentiation with an adenosine nucleotide analog 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB) which specifically blocks synthesis of new RNA polymerase II transcripts. The amount of mu heavy chain cytoplasmic RNA, measured by quantitative Northern blot analysis at various times post DRB treatment, is reflective of the transcript's stability. The mu mRNA half-life values observed from the earliest-stage lymphomas (70Z/3 and WEHI-231) are about 1.9-4 hr, whereas the t1/2 of mu mRNA in the hybridomas (Hyb54.3C2 and IdG11) is about 13-17 hr. There is, therefore, a nine-fold maximal increase in half-life of the mu mRNA in the Hyb54.3C2 over that observed in the earliest stage (70Z/3) cells.
Mol Immunol 1990 Aug
PMID:Increased half-life of mu immunoglobulin mRNA during mouse B cell development increases its abundancy. 211 79

Genes of higher eucaryotic cells are considered to show only a limited response to nutritional stress. Here we show, however, that omission of a single essential amino acid from the medium caused a marked rise in the mRNA levels of c-myc, c-jun, junB and c-fos oncogenes and ornithine decarboxylase (ODC) in CHO cells. There was no general accumulation of mRNAs in amino acid-starved cells, since the gamma-actin, beta-tubulin, protein kinase C, RNA polymerase II, and glyceraldehyde-3-phosphate dehydrogenase mRNAs and the total poly(A)+ mRNA were not increased. The levels of c-myc, ODC, and c-jun mRNAs were elevated more by amino acid starvation than by inhibition of protein synthesis with cycloheximide, which is known to increase the levels of these mRNAs. Importantly, however, cycloheximide present during amino acid starvation reduced the rise in the levels of the mRNAs down to the level obtained with cycloheximide alone. This implies that protein synthesis is required for the accumulation of c-myc, ODC, and c-jun mRNAs in amino acid-deprived cells. The junB and c-fos mRNAs, instead, were increased to the same extent or less by amino acid starvation than by cycloheximide treatment. The accumulation of the c-myc mRNA in amino acid-starved cells was due to both stabilization of the mRNA and increase of its transcription. The rise in the c-jun mRNA level seemed to be caused merely by stabilization of the mRNA. Further, despite the inhibition of general protein synthesis, amino acid starvation led to an increase in the synthesis of c-myc polypeptide. The results suggest that mammalian cells have a specific mechanism for registering shortages of amino acids in order to make adjustments compatible with cellular growth.
Mol Cell Biol 1990 Nov
PMID:Deprivation of a single amino acid induces protein synthesis-dependent increases in c-jun, c-myc, and ornithine decarboxylase mRNAs in Chinese hamster ovary cells. 212 33

Recent work has shown that many promoters recognized by eucaryotic RNA polymerase II contain essential sequences located downstream of the transcriptional initiation site. We show here that the activity of a promoter element centered 28 base pairs downstream of the simian virus 40 major late initiation site appears to be mediated by a DNA-binding protein, which was isolated by affinity chromatography from HeLa cell nuclear extracts. In the absence of the other components of the transcriptional machinery, the protein bound specifically but weakly to its recognition sequence, with a Kd of approximately 10(-8) M. Analysis of kinetic data showed that mutation of the downstream element decreased the number of functional preinitiation complexes assembled at the promoter without significantly altering the time required for half the complexes to assemble. This suggests that in the absence of the downstream activating protein, preinitiation complexes are at least partially assembled but are not transcriptionally competent.
Mol Cell Biol 1990 Jul
PMID:A downstream-element-binding factor facilitates assembly of a functional preinitiation complex at the simian virus 40 major late promoter. 216 78

We found that the 5' nontranslated leader sequence from encephalomyocarditis virus (EMCV) allowed transcripts that were synthesized by the T3 RNA polymerase in mammalian cells to be translated in a cap-independent fashion. Stable mouse cell lines that carry the T3 RNA polymerase gene expressed the chloramphenicol acetyltransferase (CAT) gene under the control of a phage promoter when the CAT gene was fused to the EMCV leader and introduced into the cells by transient DNA uptake. The level of gene expression in such cells was similar to or greater than that observed with a conventional transient expression vector that is dependent on transcription by the host RNA polymerase II. Expression of the EMCV-CAT fusion gene was stimulated by cotransfection of the cells with a gene that encodes the poliovirus protease 2A protein (which inhibits cap-dependent translation), demonstrating that the EMCV-CAT fusion gene was expressed in a cap-independent fashion. Introduction of both the T3 RNA polymerase gene and the EMCV-CAT fusion gene into a variety of cultured mammalian cell lines (HeLa, BSC40, Ltk-, NIH 3T3, and C127) demonstrated that the T3-EMCV expression system functions in a broad range of cell types.
Mol Cell Biol 1990 Sep
PMID:Synthesis of functional mRNA in mammalian cells by bacteriophage T3 RNA polymerase. 216 33

We have detected, in nuclear extracts of non-infected cultured monkey cells, a protein (protein H16) that binds a specific single-stranded DNA sequence in the early promoter of simian virus 40 (SV40). This protein does not bind double-stranded DNA, nor RNA. In the present paper, the DNA-binding properties of protein H16 and its effects on transcription by RNA polymerase II in vitro have been investigated. The protein binds only to the late strand of the early promoter, within the region of the 21 base-pair repeats, and shows no affinity for any other SV40 sequence. The high percentage of cytosine residues in the late strand in this region appears to be important for recognition by the protein. Protein H16 does not bind the control region of SV40 in negatively supercoiled DNA circles. When bound to the late strand, the protein is displaced from its binding site by reassociation of the early strand with the late strand. Its binding to DNA is not sensitive to methylation of the dinucleotide CG in its binding site. The protein has been purified to near homogeneity by preparative gel retardation, and has an apparent molecular weight of 70,000. Purified protein H16 stimulates transcription by purified RNA polymerase II in vitro. The possible role of sequence-specific single-strand-binding proteins in transcription is discussed.
J Mol Biol 1990 Sep 20
PMID:Sequence-specific single-strand-binding protein for the simian virus 40 early promoter stimulates transcription in vitro. 217 Jun 63

Drosophila hsp70 genes have an RNA polymerase II molecule paused at their 5' ends in uninduced cells. In this study we have shown that this pausing also occurs on other heat shock and constitutively expressed genes. We propose that a rate-limiting step in early elongation occurs in many Drosophila genes and may be a target for transcriptional regulation.
Mol Cell Biol 1990 Nov
PMID:Postinitiation transcriptional control in Drosophila melanogaster. 217 90

A DNA-binding protein has been identified from extracts of the budding yeast Saccharomyces cerevisiae which binds to sites present in the promoter regions of a number of yeast genes transcribed by RNA polymerase II, including SIN3 (also known as SDI1), SWI5, CDC9, and TOP1. This protein also binds to a site present in the enhancer for the 35S rRNA gene, which is transcribed by RNA polymerase I, and appears to be identical to the previously described REB1 protein (B. E. Morrow, S. P. Johnson, and J. R. Warner, J. Biol. Chem. 264:9061-9068, 1989). When oligonucleotides containing a REB1-binding site are placed between the CYC1 upstream activating sequence and TATA box, transcription by RNA polymerase II in vivo is substantially reduced, suggesting that REB1 acts as a repressor of RNA polymerase II transcription. The in vitro levels of the REB1 DNA-binding activity are reduced in extracts prepared from strains bearing a mutation in the SIN3 gene. A greater reduction in REB1 activity is observed if the sin3 mutant strain is grown in media containing galactose as a carbon source.
Mol Cell Biol 1990 Apr
PMID:Identification of a Saccharomyces cerevisiae DNA-binding protein involved in transcriptional regulation. 218 Dec 83

The two large subunits of RNA polymerase II, RPB1 and RPB2, contain regions of extensive homology to the two large subunits of Escherichia coli RNA polymerase. These homologous regions may represent separate protein domains with unique functions. We investigated whether suppressor genetics could provide evidence for interactions between specific segments of RPB1 and RPB2 in Saccharomyces cerevisiae. A plasmid shuffle method was used to screen thoroughly for mutations in RPB2 that suppress a temperature-sensitive mutation, rpb1-1, which is located in region H of RPB1. All six RPB2 mutations that suppress rpb1-1 were clustered in region I of RPB2. The location of these mutations and the observation that they were allele specific for suppression of rpb1-1 suggests an interaction between region H of RPB1 and region I of RPB2. A similar experiment was done to isolate and map mutations in RPB1 that suppress a temperature-sensitive mutation, rpb2-2, which occurs in region I of RPB2. These suppressor mutations were not clustered in a particular region. Thus, fine structure suppressor genetics can provide evidence for interactions between specific segments of two proteins, but the results of this type of analysis can depend on the conditional mutation to be suppressed.
Mol Cell Biol 1990 May
PMID:Genetic exploration of interactive domains in RNA polymerase II subunits. 218 12


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