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

A new maize homeobox gene was isolated by screening a lambda gt11 expression library with the 26 bp Shrunken feedback control element. Zmhox1a (Zea mays homeobox) is an unidentified maize gene mapping to the long arm of chromosome 8. It is a member of a new class of maize homeobox genes only distantly related to the Knotted class. The 3.1 kb Zmhox1a transcript can be detected in different maize tissues and encodes a polypeptide of 719 amino acids. Western blotting experiments detect the native 112 or 115 kDa protein in nuclear protein extracts, the nuclear localization being compatible with a function in transcriptional control. No Zmhox1a protein is detected in maize roots despite the presence of the Zmhox1a transcript; this may indicate a post-transcriptional control mechanism. A highly acidic central region of the Zmhox1a polypeptide implies a transcriptional activator function. The carboxy-terminal part of the maize homeodomain protein is related to the human Oct2 transcription factor, but homology to the POU specific domain is restricted to the POU-B subdomain. It was confirmed by DNase I footprinting experiments that DNA binding of the Zmhox1a homeodomain was at three sites flanking the TATA-box of the Shrunken promoter.
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PMID:Zmhox1a, the product of a novel maize homeobox gene, interacts with the Shrunken 26 bp feedback control element. 135 14

A number of molecules have recently been described that effect the correct transport and assembly of cytoplasmically synthesized proteins to cellular membranes. To identify proteins that bind or modify other proteins during the process of membrane translocation, we developed a yeast selection scheme that employs the yeast transcriptional activator GAL4. This selection facilitates the isolation of cDNAs that encode proteases and binding proteins for known target peptide sequences. We report the isolation of an Arabidopsis cDNA encoding a polypeptide that can interact with the amino terminus of a ligh-harvesting chlorophyll a/b-binding protein (LHCP), a cytoplasmically synthesized protein that is integral to the chloroplast thylakoid membrane. The cDNA was selected in yeast from an Arabidopsis expression library for its ability to inhibit a transcriptional activator GAL4-LHCP fusion protein, but not inhibit native GAL4 protein. The LHCP amino-terminal sequences included in the fusion protein are known to regulate LHCP biogenesis and function. The Arabidopsis cDNA encodes a 595-amino acid protein with at least two functional domains, one with similarity to the family of protein-serine/threonine kinases and another that contains an epidermal growth factor repeat. The identification of an EGF repeat in Arabidopsis indicates that the motif is conserved between the plant and animal kingdoms. Hybridization studies indicate that this gene is likely to be present in other genera of plants. Its mRNA is detected in green leaves but not in other plant tissues or in etiolated plants. The specificity in yeast and the expression pattern in plants together are suggestive of a role for this protein kinase in the assembly or regulation of LHCP.
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PMID:An Arabidopsis serine/threonine kinase homologue with an epidermal growth factor repeat selected in yeast for its specificity for a thylakoid membrane protein. 143 3

The interferon-alpha (IFN-alpha)-stimulated gene factor 3 (ISGF3), a transcriptional activator, contains three proteins, termed ISGF3 alpha proteins, that reside in the cell cytoplasm until they are activated in response to IFN-alpha. Treatment of cells with IFN-alpha caused these three proteins to be phosphorylated on tyrosine and to translocate to the cell nucleus where they stimulate transcription through binding to IFN-alpha-stimulated response elements in DNA. IFN-gamma, which activates transcription through a different receptor and different DNA binding sites, also caused tyrosine phosphorylation of one of these proteins. The ISGF3 alpha proteins may be substrates for one or more kinases activated by ligand binding to the cell surface and may link occupation of a specific polypeptide receptor with activation of transcription of a set of specific genes.
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PMID:Interferon-dependent tyrosine phosphorylation of a latent cytoplasmic transcription factor. 138 85

A specific DNA complex of the 65-residue, N-terminal fragment of the yeast transcriptional activator, GAL4, has been analysed at 2.7 A resolution by X-ray crystallography. The protein binds as a dimer to a symmetrical 17-base-pair sequence. A small, Zn(2+)-containing domain recognizes a conserved CCG triplet at each end of the site through direct contacts with the major groove. A short coiled-coil dimerization element imposes 2-fold symmetry. A segment of extended polypeptide chain links the metal-binding module to the dimerization element and specifies the length of the site. The relatively open structure of the complex would allow another protein to bind coordinately with GAL4.
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PMID:DNA recognition by GAL4: structure of a protein-DNA complex. 155 14

CPC1 is the transcriptional activator of amino acid biosynthetic genes of Neurospora crassa. CPC1 function in vivo was abolished upon deletion of segments of cpc-1 corresponding to the presumed transcription activation domain, the DNA-binding and dimerization domains, or a 52-residue connector segment of CPC1. A truncated CPC1 polypeptide containing only the carboxy-terminal 57-residue segment of CPC1 was sufficient to form homodimers that bound DNA. However, deletion of the segment of cpc-1 corresponding to the connector segment in the full-length CPC1 polypeptide abolished DNA binding. Removal of a segment of cpc-1 corresponding to the GIn-rich region of CPC1 reduced in vivo function only slightly. The homologous transcription activator of Saccharomyces cerevisiae, GCN4, did not substitute for CPC1 in N. crassa. Chimeric CPC1-GCN4 polypeptides that contained the GCN4 transcriptional activation domain or the domain of GCN4 that corresponds to the essential 52-residue connector segment of CPC1, functioned with reduced efficiency. However, a chimeric polypeptide containing the GCN4 DNA-binding and dimerization domains in place of those of CPC1 functioned essentially as well as wild-type CPC1. The basic and dimerization domains of CPC1 were characterized by introducing deletions or site-directed amino acid replacements. The basic region was required for DNA binding but not for dimerization. CPC1 has a short dimerization domain containing heptad residues Leu-1, Leu-2, Trp-3, and His-4. When Val was substituted for Leu-1 or Leu-2, CPC1 was fully active, but when Val replaced Trp-3, dimerization and DNA binding were prevented. DNA band shift analyses with CPC1 heterodimers demonstrated that CPC1 does not require aligned heptad leucine residues for dimerization. Replacement of two charged residues located between Leu-1 and Leu-2 of CPC1 abolished dimerization and DNA binding.
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PMID:Characterization of Neurospora CPC1, a bZIP DNA-binding protein that does not require aligned heptad leucines for dimerization. 182 60

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

Varicella-zoster (VZV) gene 62 encodes a protein with a predicted Mr of 140,000 (140K) which has considerable amino acid identity with the major immediate early (IE) protein Vmw175 (ICP4) of herpes simplex virus type I (HSV-1). Vmw175 is an essential virus polypeptide with a pivotal role in the activation of early and late viral gene expression and also in the repression of IE gene expression. The VZV 140K protein has been shown to function as a strong transcriptional activator in transfection assays and largely complements for the loss of Vmw175 function in HSV-1. We report the results of cotransfection experiments which demonstrate that the 140K protein strongly represses expression from its own promoter, that of gene 62, thus establishing further functional similarity between it and Vmw175. However, whereas Vmw175 can substitute for the 140K protein in repression of the gene 62 promoter, the 140K protein does not repress the HSV-1 IE3 promoter in the reciprocal experiment. The integrity of a domain of Vmw175 (designated region 2), previously shown to be crucial for repression of the HSV-1 IE3 promoter, is also required for repression of the gene 62 promoter. Moreover, a similar requirement for the highly similar region 2 of the 140K protein for repression is demonstrated, suggesting that VZV 140K protein and HSV-1 Vmw175 autoregulate IE gene expression by a related mechanism.
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PMID:The product of varicella-zoster virus gene 62 autoregulates its own promoter. 217 91

The murine, erythroid DNA-binding protein GF-1 (also known as NF-E1, Eryf 1), a 413-amino acid polypeptide with two novel finger domains of the Cx-Cx variety, recognizes a consensus GATA motif present in cis elements of the majority of erythroid-expressed genes. We have performed a structure-function analysis of this protein to evaluate its potential as a transcriptional activator and to examine the role of the finger domains in DNA binding. Using a cotransfection assay, we find that GF-1 is a potent transcriptional activator with several activation domains but that this is revealed only in heterologous cells and with reporters containing minimal promoters onto which either a single or multiple GATA-binding sites are placed. The two fingers of GF-1 are functionally distinct and cooperate to achieve specific, stable DNA binding. The amino finger is necessary only for full specificity and stability of binding, whereas the carboxyl finger is required for binding. The role of each finger is more pronounced with some GATA-binding sites than with others, suggesting a diversity of interactions between GF-1 and different target sites. The complex activation and DNA-binding properties of GF-1 are likely to contribute to the ability of this single protein to participate widely in gene expression throughout erythroid development.
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PMID:Transcriptional activation and DNA binding by the erythroid factor GF-1/NF-E1/Eryf 1. 227 23

We have purified extensively the transcriptional activator, GAL4, from a yeast strain overexpressing the gene product from the ADH1 promoter. Our purification followed GAL4 activity by its binding to a specific DNA target sequence, using filter binding assays. No specific binding activity was detected in extracts from a strain containing a disrupted copy of the GAL4 gene. The purification protocol included fractionation of a whole cell extract by ion-exchange and DNA-affinity chromatography on a column containing a 17-base pair oligomer encoding a near consensus GAL4 binding site. Two polypeptides co-eluted with the GAL4 DNA binding activity from the DNA-affinity column. One had an apparent molecular mass of 99 kDa (the predicted size of the GAL4 protein) and cross-reacted with antibodies raised against GAL4 epitopes from fusion proteins expressed in bacterial cells. The second polypeptide did not cross-react with the anti-GAL4 antibody and is presumed to be the GAL80 transcriptional repressor based on its size (48 kDa) and known physical association with the GAL4 protein. GAL4 binding activity elutes from a gel filtration column as a 155-kDa species suggesting that it exists in solution in a heterodimer complex of one GAL4 and one GAL80 molecule. The dissociation constant of the DNA-affinity-purified GAL4-GAL80 complex for a 900-base pair DNA fragment containing the UASGAL element from the GAL1-GAL10 divergent promoter was, Kd(effective) (0.15 M KCl) = 2.4 x 10(-9) M.
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PMID:Purification and characterization of the yeast transcriptional activator GAL4. 240 56

Many eukaryotic proteins involved in transcriptional regulation contain within their DNA-binding domains a polypeptide loop (the zinc finger) which interacts with DNA. In proteins possessing multiple zinc fingers, including TFIIIA, Sp1, SWI5 and oestrogen/glucocorticoid receptors, the region containing the zinc fingers confers DNA-binding specificity. By contrast, our results demonstrate that all but one of the 28 amino acids encompassing the single zinc-finger region of GAL4, the yeast transcriptional activator, can be replaced with the analogous zinc-finger region from another yeast-activator protein, PPR1, without changing the DNA-binding specificity of GAL4. A 14-amino-acid region adjacent to the zinc finger is necessary for determining specific recognition of DNA sequences.
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PMID:Altering DNA-binding specificity of GAL4 requires sequences adjacent to the zinc finger. 250 85


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