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: UNIPROT:P51532 (transcriptional activator)
6,546 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

DNA replication from the plasmid origin of replication of Epstein-Barr virus requires one viral protein, EBNA1. This protein also acts as a transcriptional activator. Mutational analyses of EBNA1 have led to the conclusion that it supports transcription and DNA replication similarly. Such analyses have not probed the DNA-binding domain of EBNA1. To test whether domains of EBNA1 specifically required for either transcription or replication lie within its DNA-binding domain, we constructed a functional transcriptional activator by placing the EBNA1 DNA-binding domain in the context of the activation domains of the estrogen receptor. This hybrid protein did not support DNA replication, which indicates that the DNA-binding domain does not contain a replication-specific domain that can function along with heterologous transcriptional activating domains.
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PMID:A chimera of EBNA1 and the estrogen receptor activates transcription but not replication. 173 8

The promoter specificity of transcriptional activators is generally thought to be conferred by the specificity of the DNA-binding domain, which brings the activation domain to the appropriate promoter sequence. We show here, however, that Oct-1 and Oct-2 can differentially activate transcription not through DNA binding specificity but instead through the use of promoter-selective activation domains. These distinct activation domains lead to stimulation of the U2 small nuclear RNA promoter by Oct-1 and an mRNA promoter by Oct-2. An Oct-2 variant, called Oct-2B, differs from Oct-2 by an Oct-1-related C-terminal extension that results from alternative splicing. This variant gains the ability to activate the U2 small nuclear RNA promoter. Thus, the promoter selectivity of a transcriptional activator can be changed, in this case by alternative splicing, without affecting its DNA binding specificity.
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PMID:Promoter-selective activation domains in Oct-1 and Oct-2 direct differential activation of an snRNA and mRNA promoter. 173 80

Using a DNA probe from the DNA-binding portion of the NF-IL6 gene and an antibody against the DNA-binding domain of NF-IL6, we isolated a gene homologous to NF-IL6 in the DNA-binding and leucine zipper domains. This intronless gene, termed NF-IL6 beta encodes a 269-amino acid protein with a potential leucine zipper structure, and the gene product can bind to the CCAAT homology as well as the viral enhancer core sequence, as in the cases of NF-IL6 and C/EBP. This gene is expressed at an undetectable or a minor level in normal tissues but is induced by lipopolysaccharide or inflammatory cytokines, as in the case of NF-IL6. NF-IL6 beta easily forms a heterodimer with NF-IL6 in vitro and the heterodimeric complex binds to the same DNA sequence as the respective homodimers. When examined by transient luciferase assays, NF-IL6 beta is consistently a stronger transactivator than NF-IL6. Furthermore, NF-IL6 beta shows a synergistic transcriptional effect with NF-IL6. These data suggest that NF-IL6 beta is an important transcriptional activator in addition to NF-IL6 in regulation of the genes involved in the immune and inflammatory responses.
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PMID:A member of the C/EBP family, NF-IL6 beta, forms a heterodimer and transcriptionally synergizes with NF-IL6. 174 2

Tax1 of human T-cell leukemia virus type 1 (HTLV-1) activates viral transcription dependent upon three 21-bp enhancer elements in the long terminal repeat. Difficulties in detecting any association of Tax1 with the viral enhancer have hampered elucidation of the molecular mechanisms of Tax1-mediated transcriptional activation. By constructing a fusion protein with the heterologous DNA-binding domain of yeast GAL4, Tax1 was shown to be a potent transcriptional activator dependent on the presence of GAL4-binding sites. Deletions of the Tax1 portion of the fusion protein revealed that almost the entire region of Tax1 (amino acids 2-337) is required for activation, and the activity correlated well with that of the viral enhancer. The GAL/Tax1 mutant lacking 41 residues of the C-terminus of Tax1, GAL/Tax1(2-312), was inactive for the viral enhancer, but activity was recovered by adding the heterologous activation domain of herpes simplex virus VP16. These results indicate that Tax1 has two distinct but overlapping functional domains for transcriptional activation and for enhancer specificity. Thus, Tax1 is thought to be a transcription factor acting in the enhancer complex rather than as a catalytic or allosteric modifier of pre-existing cellular transcription factors.
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PMID:HTLV-1 Tax has distinct but overlapping domains for transcriptional activation and for enhancer specificity. 176 79

We present evidence that CRE-BP1 binding to the cyclic AMP (cAMP) response element (CRE) is a transcriptional activator. Transcriptional activation was assayed by cotransfection into CV-1 cells of a CRE-BP1 expression plasmid together with a reporter plasmid in which the thymidine kinase promoter and four tandem repeats of CRE were linked to the chloramphenicol acetyltransferase (CAT) gene. Cotransfection with the CRE-BP1 expression plasmid caused an 8-fold stimulation of CAT activity, while cotransfection with the plasmids to express CRE-BP1 and c-Jun induced a 32-fold stimulation of CAT activity, suggesting that a heterodimer of CRE-BP1 with c-Jun is a stronger trans-activator than a homodimer of CRE-BP1. By using a series of deletion and point mutants of CRE-BP1 in this cotransfection assay, two functional domains of CRE-BP1 were identified: the putative metal finger structure in the amino-terminal region and the leucine zipper motif linked to a cluster of basic amino acids in the carboxyl-terminal region. The former was a transcriptional activation domain in the absence of c-Jun. The latter was a DNA-binding domain, and was essential in both the presence and absence of c-Jun.
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PMID:Identification of the functional domains of the transcriptional regulator CRE-BP1. 183 93

Many eukaryotic transcriptional activator proteins contain a DNA-binding domain that interacts with specific promoter sequences and an acidic activation region that is required to stimulate transcription. Transcriptional enhancement by such activator proteins is often synergistic and promiscuous; promoters containing multiple binding sites for an individual protein or even for unrelated proteins can be 10-100 times more active than promoters with single sites. It has been suggested that such synergy reflects a nonlinear response of the basic transcription machinery to the number and/or quality of acidic activation regions. Here, we determine the transcriptional activity of Jun-Fos heterodimers containing one or two GCN4 acidic activation regions on promoters containing one or two Ap-1 target sites. Surprisingly, heterodimers with one or two acidic regions activate transcription with similar efficiency and are equally synergistic (10- to 15-fold) on promoters containing two target sites. Thus, transcriptional synergy does not depend on the number of acidic activation regions but rather on the number of proteins bound to the promoter. This suggests that synergy is mediated either by cooperative DNA binding or by alternative mechanisms in which the DNA-binding domain plays a more direct role in transcription (e.g., changes in DNA structure, nucleosome displacement, or direct interactions with the transcriptional machinery).
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PMID:Synergistic transcriptional enhancement does not depend on the number of acidic activation domains bound to the promoter. 189 73

The nucleotide sequence of nirA, mediating nitrate induction in Aspergillus nidulans, has been determined. Alignment of the cDNA and the genomic DNA sequence indicates that the gene contains four introns and encodes a protein of 892 amino acids. The deduced NIRA protein displays all characteristics of a transcriptional activator. A putative double-stranded DNA-binding domain in the amino-terminal part comprises six cysteine residues, characteristic for the GAL4 family of zinc finger proteins. An amino-terminal highly acidic region and two proline-rich regions are also present. The nucleotide sequences of two mutations were determined after they were mapped by transformation with overlapping DNA fragments, amplified by the polymerase chain reaction. nirA87, a mutation conferring noninducibility by nitrate and nitrite, has a -1 frameshift at triplet 340, which eliminates 549 C-terminal amino acids from the polypeptide. Under the assumption that the truncated polypeptide is stable, it comprises the zinc finger domain and the acidic region, which seem not sufficient for transcriptional activation. nirAd-106, an allele conferring nitrogen metabolite derepression of nitrate and nitrite reductase activity, includes two transitions, changing a glutamic acid to a lysine and a valine to an alanine, situated between a basic and a proline-rich region of the protein. Northern (RNA) analysis of the wild type and of constitutive (nirAc) and derepressed (nirAd) mutants show that the nirA transcript does not vary between these strains, being in all cases constitutively expressed. On the other hand, transcript levels of structural genes (niaD and niiA) do vary, being highly inducible in the wild type but constitutively expressed in the nirAc mutant. The nirAd mutant appears phenotypically derepressed, because the niaD and niiA transcript levels are overinduced in the presence of nitrate but are still partially repressed in the presence of ammonium.
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PMID:nirA, the pathway-specific regulatory gene of nitrate assimilation in Aspergillus nidulans, encodes a putative GAL4-type zinc finger protein and contains four introns in highly conserved regions. 192 75

Oncogenic forms of the c-myb protein (Myb) often exhibit amino-terminal and/or carboxyl-terminal truncations. When the transcriptional activity of these proteins was examined it was found that carboxyl-truncated Myb is more effective as a transcriptional activator than full-length or amino-truncated Myb. In order to determine the effect of such truncations on sequence-specific DNA binding, we synthesized murine Myb in vitro and assessed DNA binding by using a mobility-shift assay. Compared with the full-length protein no difference in binding was observed following deletion of the amino terminus, despite the removal of much of the first repeat of the DNA-binding domain. However, the specific DNA-binding capacity of carboxyl-truncated Myb was 4-6 times greater than that of the full-length protein; moreover, DNA binding was independent of a 'leucine zipper' motif present in Myb. These observations suggest that the increased transforming and transactivating potential of carboxyl-truncated Myb is due, at least in part, to increased sequence-specific DNA binding.
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PMID:Increase in specific DNA binding by carboxyl truncation suggests a mechanism for activation of Myb. 192 10

The adaptive response of Escherichia coli protects cells against the mutagenic and toxic effects of alkylating agents. This response is controlled by the Ada protein, which not only functions as the transcriptional activator of the ada and alkA genes but also possesses two DNA methyltransferae activities. Ada is converted into an efficient transcriptional activator by transferring a methyl group from a DNA methylphosphotriester to its own Cys-69 residue and then binds to a DNA sequence (the Ada box) present in both the ada and alkA promoters. Although the Ada protein initially appeared to regulate the ada and alkA genes in a similar fashion, our studies show that the wild-type Ada protein and its truncated derivatives can differentially regulate ada and alkA transcription. In vivo, lower levels of wild-type methylated Ada are needed to activate ada transcription than alkA transcription. In cells exposed to alkylating agents, the N-terminal half of Ada, which contains the DNA-binding domain, is sufficient for efficient activation of alkA, but not ada, transcription. Moreover, truncated derivatives containing 80-90% of Ada are extremely strong constitutive activators of ada but are only inducible activators of alkA transcription. These results suggest that the mechanism by which Ada activates ada transcription differs from that by which it activates alkA transcription.
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PMID:A region of the Ada DNA-repair protein required for the activation of ada transcription is not necessary for activation of alkA. 192 63

LAP, a transcriptional activator, and LIP, a transcriptional repressor, are translated from a single mRNA species by using two AUGs within the same reading frame. These two proteins share the 145 C-terminal amino acids that contain the basic DNA-binding domain and the leucine zipper dimerization helix. Probably owing to its higher affinity for its DNA cognate sequences, LIP can attenuate the transcriptional stimulation by LAP in substoichiometric amounts. As revealed by transient transfection experiments, a moderate increase in the LAP/LIP ratio results in a significantly higher transcriptional activation of an appropriate target gene. The LAP/LIP ratio increases about 5-fold during terminal rat liver differentiation and is thus likely to modulate the activity of LAP in the intact animal.
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PMID:A liver-enriched transcriptional activator protein, LAP, and a transcriptional inhibitory protein, LIP, are translated from the same mRNA. 193 61


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