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

The X. laevis tRNA((Ser)Sec) gene is different from the other tRNA genes in that its promoter contains two external elements, a PSE and a TATA box functionally equivalent to those of the U6 snRNA gene. Of the two internal promoters governing classical tRNA gene transcription, only subsists the internal B box. In this report, we show that the tRNA((Ser)Sec) contains in addition an activator element (AE) which we have mapped by extensive mutagenesis. Activation is only dependent on a 15 bp fragment residing between -209 and -195 and containing an SPH motif. In vitro, this element forms a complex with a nuclear protein which is different from the TEF-1 transcriptional activator that binds the SV40 Sph motifs. This AE is versatile since it shows capacity of activating a variety of genes in vivo, including U1 and U6 snRNAs and HSV thymidine kinase. Unexpectedly for an snRNA-related gene, the tRNA((Ser)Sec) is deprived of octamer or octamer-like motifs. The X.laevis tRNA((Ser)Sec) gene represents the first example of a Pol III snRNA-type gene whose activation of transcription is completely octamer-independent.
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PMID:Optimal tRNA((Ser)Sec) gene activity requires an upstream SPH motif. 131 Oct 68

Transcription of the complete mouse mammary tumor virus (MMTV) proviral genome in mouse cells is controlled by a strong promoter in its long terminal repeat. In the mouse T lymphoma EL4, there is a second, activation-dependent transcriptional initiation site within the envelope (env) gene, from which a short mRNA is generated, encoding the open reading frame of the long terminal repeat. We now report the isolation of a segment of the MMTV env gene (called META, for MMTV env transcriptional activator) which has the expected transcription-activating properties seen in EL4.E1 cells. Namely, it induces activation-dependent, T-lymphocyte-specific transcription of a chloramphenicol acetyltransferase reporter gene. It is active in mouse or human T-helper lymphocyte lines when they are stimulated to transcribe lymphokine genes but is inactive in unstimulated T-helper cells, fibroblasts, a cytotoxic T-lymphocyte line, and a mastocytoma cell line. Its activity is inhibited by cyclosporin A, a specific inhibitor of lymphokine transcription. Several forms of the META have been isolated from EL4.E1 cells, a mouse T-helper cell hybridoma, and from BALB/c spleen cells. Linked to the heterologous thymidine kinase promoter, a 400-bp portion of it is an inducible, orientation-independent, and cyclosporin A-sensitive transcriptional activator in T-helper cells.
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PMID:An activation-dependent, T-lymphocyte-specific transcriptional activator in the mouse mammary tumor virus env gene. 132 Jan 98

The ets oncogene superfamily consists of a family of sequence-specific DNA-binding proteins that activate transcription. We have previously identified two new members of the ets oncogene superfamily, namely elk-1 and elk-2. In this report we show that the recombinant elk-1 protein expressed in bacteria, like the c-ets-1 proto-oncogene, binds in a sequence-specific manner to Moloney murine sarcoma virus long terminal repeat, E74 target sequences and the PEA3 motif (polyoma enhancer), but does not bind to PU box sequences. Thus analysis of the DNA-binding specificity of ets-related proteins supports the view that different members show similar DNA-binding specificity, which is a general feature of the homeobox proteins. Our data using the chloramphenicol acetyltransferase gene linked to a thymidine kinase promoter containing multimers of the elk-1 target sequence indicates that elk-1 functions as a transcriptional activator. Interestingly, although elk-1 is the most divergent of all the members of the ets gene family, it shows very close similarities with c-ets-1 in some of its sequence-specific DNA-binding specificities. Here, we propose a new function for the elk-1 gene to act as a transcriptional activator of retroviruses and DNA tumor viruses.
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PMID:A divergent ets-related protein, elk-1, recognizes similar c-ets-1 proto-oncogene target sequences and acts as a transcriptional activator. 174 Nov 66

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

In-frame codon insertion and deletion mutants were constructed in a plasmid containing the sequence that encodes ICP0, a transcriptional activator of herpes simplex virus type 1 (HSV-1). The effect of these mutations was analyzed in a transient expression assay using the promoters for, the IE-0 gene (an immediate early (alpha) gene), the thymidine kinase gene (an early (beta) gene), and the glycoprotein C gene (a late (gamma) gene) fused to reporter cassettes that encoded either beta-galactosidase or chloramphenicol acetyl transferase. Assays were performed in the presence or absence of a plasmid encoding ICP4, the major regulatory protein of HSV-1. Our results demonstrate that ICP0-mediated transactivation varied depending on the position of the insertion in the gene. One region of this protein was consistently shown to be required for full activation of each promoter examined either in the presence or in the absence of ICP4. This region overlaps with a cysteine-rich region and coincides with a transactivator domain identified in another extensive mutational analysis of this sequence. Analysis of the deletion mutants generated in this study demonstrated that the carboxy-terminal regions were required for activation in certain circumstances and that this varied depending on the promoter being assayed and the cell type in which the analysis was performed.
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PMID:Mutational analysis of the sequence encoding ICP0 from herpes simplex virus type 1. 184 23

The herpes simplex virus type 1 (HSV-1) ICP4 protein is a transcriptional activator of many eucaryotic RNA polymerase II promoters. The HSV-1 thymidine kinase gene (tk) promoter is induced by ICP4 and contains binding sites for the cellular transcription factors TFIID, Sp1, and CCAAT-binding proteins, each of which affects expression of the tk gene. In this study, the effects of mutations in these sites on the transcription of tk in the presence and absence of ICP4 were determined during viral infection. Only the TATA box was necessary for efficient expression in the presence of ICP4; however, ICP4 apparently can still induce tk transcription even when the TATA box is disrupted. Alteration of the Sp1 sites had a minor effect on ICP4-induced expression in comparison to a large effect in the absence of ICP4, indicating that ICP4 can operationally substitute for the function of the transcription factor Sp1. In addition, tk was still expressed with the kinetics of an early gene in the absence of binding sites for Sp1 and CCAAT-binding proteins.
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PMID:Herpes simplex virus transactivator ICP4 operationally substitutes for the cellular transcription factor Sp1 for efficient expression of the viral thymidine kinase gene. 184 84

The IE-0 gene of herpes simplex virus type 1 (HSV-1) contains two introns and encodes ICP0, a powerful transcriptional activator. We have isolated a cDNA clone that encodes ICP0 from a lambda gt10 cDNA library constructed from RNAs made from HSV-1-infected HeLa cells. DNA sequence analysis of this clone confirmed the predicted intron/exon boundaries (L. J. Perry, F. J. Rixon, R. D. Everett, M. C. Frame, and D. J. McGeoch, J. Gen. Virol. 67:2365-2380, 1986). Following transfection, a plasmid containing the cDNA copy of IE-0 directed the synthesis of ICP0, which was appropriately compartmentalized and distributed in the nucleus, as revealed by immunofluorescence. A transient expression assay was used to demonstrate that this cDNA copy retained the ability to transactivate the HSV-1 promoters for the IE-0 gene (an immediate-early gene), the thymidine kinase gene (an early gene), and the glycoprotein C gene (a late gene). The product of this cDNA clone cooperated with ICP4 to activate expression from the thymidine kinase gene promoter in a synergistic manner. The availability of a functional cDNA copy encoding ICP0 provides the opportunity to express this protein in vector systems that do not recognize eucaryotic donor and acceptor splicing signals to overexpress ICP0.
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PMID:Isolation and characterization of a functional cDNA encoding ICP0 from herpes simplex virus type 1. 184 9

The mouse gene Krox-24 is transiently activated during cell cycle reentry. It encodes a protein with three zinc fingers similar to those of the transcription factor Sp1. Here we present a biochemical characterization of the gene products. Krox-24 mRNA is translated into two proteins of 82 and 88 kilodaltons, designated p82Krox-24 and p88Krox-24, respectively. p82Krox-24 is initiated at the first AUG codon of the open reading frame, whereas synthesis of p88Krox-24 starts at a non-AUG codon located upstream. Both proteins were synthesized in HeLa cells infected with recombinant vaccinia viruses expressing Krox-24 cDNAs. Under these conditions, they were found phosphorylated on serine residues and glycosylated. The availability of the proteins made possible the determination of the DNA recognition sequence. In vitro, Krox-24 bound specifically to the sequence 5'-GCG(C/G)GGGCG-3'. This sequence is similar but not identical to the Sp1 target sequence. Insertion of an oligomer for the binding site in cis, close to the herpes simplex virus thymidine kinase promoter, rendered this promoter responsive to Krox-24. Krox-24 is therefore a sequence-specific transcriptional activator. Krox-24-binding sites were found upstream of several serum-inducible genes, raising the possibility that Krox-24 is involved in the regulation of these genes.
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PMID:The serum-inducible mouse gene Krox-24 encodes a sequence-specific transcriptional activator. 211 74

Plasmids containing the varicella zoster virus (VZV) open reading frames (ORFs) 61 and 62 were used in a transient co-transfection assay to test for trans-activation of the VZV and herpes simplex virus type 1 (HSV-1) thymidine kinase (tk) promoters. The trans-activating potential of the polypeptides encoded by these VZV ORFs, designated p51 and p140, was compared to that of their HSV-1 homologs ICP0 and ICP4, respectively. VZV p51 was functionally inactive in this system while p140 appeared to be a much stronger transcriptional activator than ICP4. Co-transfection of plasmids encoding VZV p140 and HSV-1 ICP0 resulted in a synergistic activation of the reporter gene as has been shown for the combination of ICP4 and ICP0.
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PMID:Trans-activation of viral tk promoters by proteins encoded by varicella zoster virus open reading frames 61 and 62. 215 90

Tissue-specific expression of the human insulin gene is regulated by cis-acting DNA elements 5' to the transcription start site. Deletion of the 5' region of the human insulin gene between nucleotides -279 and -258 caused a 25-fold rise in transcriptional activity whereas further deletion to nucleotide -229 reduced transcription activity 25-fold. In vitro analysis of protein binding in the 5' regulatory region revealed: (i) the major positive regulatory region (-258 to -229) contains a protein-binding site (GC-II) with 75% sequence identity to a motif in the rat insulin I gene, shown to be a powerful transcriptional activator. GC-II motif-binding factors are not restricted to insulin-producing cell lines. (ii) An islet cell-specific factor binds between nucleotides -217 to -210 (CT-II motif). (iii) A region between nucleotides -153 and -127, containing two identical motifs, GG-I and GG-II was also revealed. GG-I-binding factors are ubiquitous, whereas binding to the GG-II motif is beta cell-specific. (iv) A ubiquitous factor binds to a motif between nucleotides -179 and -183, identical to a half-site for the cyclic nucleotide regulatory element. (v) The negative regulatory element between -279 and -258 contains overlapping binding sites for at least 3 protein factors, with differing cell-specific distributions and can independently down-regulate thymidine kinase promoter activity in a beta cell line.
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PMID:Positive and negative regulation of the human insulin gene by multiple trans-acting factors. 218 40


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