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: EC:2.7.7.6 (RNA polymerase)
34,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A phosphoprotein kinase (ATP : protein phosphotransferase, EC 2.7.1.37) from calf thymus nuclei was purified by DEAE-cellulose chromatography, hydroxyapatite, and Sepharose 6B gel filtration. The enzyme is a cyclic AMP-independent protein kinase by the following criteria: (a) the protein kinase did not bind cyclic AMP; (b) no inhibition of activity was obtained with the heat-stable protein kinase inhibitor from rabbit skeletal muscle; (c) the regulatory subunit of cyclic AMP-dependent protein kinase had no effect on activity; and (d) no inhibition was obtained with antibody to cyclic AMP-dependent protein kinase. The nuclear cyclic AMP-independent protein kinase readily phosphorylated protamine on serine and to a lesser extent on threonine. Homologous nucleoplasmic RNA polymerase (EC 2.7.7.6) is a better substrate than arginine-rich histone, phosvitin or casein. Physical characteristics of the enzyme are described.
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PMID:Purification and properties of a cyclic AMP-independent protein kinase from calf thymus nuclei. 2 35

An acidic nucleolar phosphoprotein with a subunit M(r) of 70,000 was purified as an apparent dimer of 139,000 from isolated nuclei of the slime mold Physarum polycephalum. The protein was purified without the aid of strong dissociating agents after its selective phosphorylation in isolated nuclei by a polyamine-mediated reaction. Its amino acid composition resembled that of a nucleolar phosphoprotein from Novikoff hepatoma ascites cells. The phosphoprotein stimulated rRNA synthesis 5-fold by RNA polymerase I within a nucleolar, ribosomal deoxyribonucleoprotein complex isolated from nucleoli of P. polycephalum. It was also identified as a component of the complex. It bound with high affinity and specificity to the palindromic ribosomal DNA of 38 x 10(6)M(r) from P. polycephalum, which contained two coding sequences for 5.8S, 19S, and 26S rRNA. It also bound to three fragments of ribosomal DNA of M(r) 21.2 x 10(6), 17.1 x 10(6), and 8.1 x 10(6), prepared by cleavage with restriction endonucleases HindIII, PstI, and BamHI, respectively. All of these fragments included the symmetry axis of the palindromic ribosomal DNA. The phosphoprotein that had been treated with alkaline phosphataseagarose to hydrolyze the phosphate groups did not stimulate transcription and did not bind to ribosomal DNA or to the restriction fragments indicated. We have thus isolated a specific phosphoprotein with the capacity to stimulate transcription of a specific set of genes in a eukaryote. These findings suggest that this phosphoprotein may specifically regulate functions of ribosomal DNA in a manner dependent on its degree of phosphorylation.
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PMID:Polyamine-mediated phosphorylation of a nucleolar protein from Physarum polycephalum that stimulates rRNA synthesis. 28 43

The association of an RNA-dependent RNA polymerase activity with virions of pike fry rhabdovirus has been demonstrated by both in vitro and in vivo studies. The temperature optimum for the in vitro assay is around 20 C, although enzyme activity can be observed at 4 C. Preparations of pike fry virus possess a glycoprotein, a membrane protein, a nucleoprotein, an L protein, and a phosphoprotein, as well as an RNA of about 3.8 times 10-6 mol wt. A protein kinase activity has been found associated with virus preparations. In vitro RNA product analyses indicate that the virus-associated enzyme functions principally as a transcriptase synthesizing viral-complementary, heteropolymeric RNA.
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PMID:RNA polymerase associated with virions of pike fry rhabdovirus. 116 3

The phosphorylated state of the vesicular stomatitis virus phosphoprotein (P), an essential component of the virion-associated RNA polymerase complex, has been shown to be important for the transcriptional activity of the complex. Recent studies indicate that phosphorylation within the acidic domain of the P protein by cellular casein kinase II is necessary for its activity. In an attempt to identify the exact location of the cell kinase-mediated phosphorylation, we altered specific serine and threonine residues within the acidic domain of the New Jersey serotype of P protein by site-directed mutagenesis. The altered P proteins were then tested to determine what effect these mutations had on the phosphorylated state of the protein in vivo as well as its transcriptional activity in vitro. We report that serine residues 59 and 61 within the acidic domain of the P protein must be phosphorylated for it to be functionally active in a reconstituted transcription assay. These results demonstrate the importance of site-specific phosphorylation in the transcriptional activity of a negative-strand RNA viral phosphoprotein and the crucial role played by a cell protein kinase in this process.
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PMID:Phosphorylation of specific serine residues within the acidic domain of the phosphoprotein of vesicular stomatitis virus regulates transcription in vitro. 132 45

The complete nucleotide sequence of the simian virus 41 (SV41) large (L) protein gene was determined. The L gene spanned 6883 nucleotides including a putative trailer RNA, and the L mRNA contained a single large open reading frame encoding a polypeptide of 2269 amino acids. Dot-matrix comparisons under stringent conditions identified domains highly conserved among paramyxoviruses. Domain 3 is the most highly conserved, and has been hypothesized to be the RNA polymerase active site. A phylogenetic tree was constructed from the sequences of the L proteins of seven paramyxoviruses. SV41 was most closely related to human parainfluenza virus type 2 (HPIV-2), and SV41, HPIV-2 and SV5 form a subgroup. The intergenic sequences at the nucleocapsid protein-phosphoprotein and haemagglutinin-neuraminidase-L protein gene junctions, and the 5' trailer sequence of SV41 were also determined, and it was shown that the first 13 nucleotides of the 5' trailer sequence are complementary to those of the 3' leader sequence. The intergenic, and gene-start and -end sequences of SV41, HPIV-2 and SV5 are shown.
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PMID:Nucleotide sequence analysis of the simian virus 41 gene encoding the large (L) protein and construction of a phylogenetic tree for the L proteins of paramyxoviruses. 132 85

UBF is a DNA binding protein which interacts with both the promoter and the enhancer of various vertebrate ribosomal RNA genes and functions as a transcription initiation factor for RNA polymerase I (pol I). We have purified murine UBF to apparent molecular homogeneity and demonstrate that its transactivating potential, but not its DNA binding activity, is modulated in response to cell growth. In vivo labelling experiments demonstrate that UBF is a phosphoprotein and that the phosphorylation state is different in growing and quiescent cells. We show that UBF is phosphorylated in vitro by a cellular protein kinase which by several criteria closely resembles casein kinase II (CKII). A major modification involves serine phosphoesterifications in the carboxy terminal hyperacidic tail of UBF. Deletions of this C-terminal domain severely decreases the UBF directed activation of transcription. The data suggest that phosphorylation of UBF by CKII may play an important role in growth dependent control of rRNA synthesis.
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PMID:The nucleolar transcription factor mUBF is phosphorylated by casein kinase II in the C-terminal hyperacidic tail which is essential for transactivation. 160 Sep 46

Utilizing nonionic detergent lysates of human lymphoid and non-lymphoid cells as substrate, IgM and/or IgG antibodies to a 110-kDa/isoelectric point 5.4 phosphoprotein (110K) was demonstrated in serum from patients with SLE or certain other systemic autoimmune disorders by immunoblotting and immunoprecipitation. Ig of this specificity was not demonstrable in serum from normal individuals, but, in a limited survey, was detected in serum from patients with acute hepatitis A or infectious mononucleosis. 110K shares a number of properties with nucleolin, i.e., identical Mr and isoelectric point, localization in both the nucleus and the cytosol, increased expression in rapidly dividing cells, and shown to be distinct from already defined autoantigens of similar size, i.e., topoisomerase I, PM-Scl, and RNA polymerase I. Because 110K could bind denatured DNA, as demonstrated by its specific absorption by DNA-cellulose and by its reactivity with monoclonal anti-ssDNA antibody in the presence of denatured DNA, special efforts were made to distinguish reactivity of pre-formed DNA/anti-DNA complexes in SLE serum from that due to specific anti-110K autoantibodies. Although binding to 110K could be mediated by DNA and anti-DNA in some SLE sera, the accumulated evidence supports the existence of a major new autoantibody system in SLE, other autoimmune diseases, and certain virus infections.
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PMID:Reactivity of autoantibodies and DNA/anti-DNA complexes with a novel 110-kilodalton phosphoprotein in systemic lupus erythematosus and other diseases. 168 48

An alternative approach to structure-function analysis of vesicular stomatitis virus (VSV) gene products and their interactions with one another during each phase of the viral life cycle is described. We showed previously by using the vaccinia virus-T7 RNA polymerase expression system that when cells expressing the nucleocapsid protein (N), the phosphoprotein (NS), and the large polymerase protein (L) of VSV were superinfected with defective interfering (DI) particles, rapid and efficient replication and amplification of (DI) particle RNA occurred. Here, we demonstrate that all five VSV proteins can be expressed simultaneously when cells are contransfected with plasmids containing the matrix protein (M) gene and the glycoprotein (G) gene of VSV in addition to plasmids containing the genes for the N, NS, and L proteins. When cells coexpressing all five VSV proteins were superinfected with DI particles, which because of their defectiveness are unable to express any viral proteins or to replicate, DI particle replication, assembly, and budding were observed and infectious DI particles were released into the culture fluids. Omission of either the M or G protein expression resulted in no DI particle budding. The vector-supported DI particles were similar in size and morphology to the authentic DI particles generated from cells coinfected with DI particles and helper VSV and their infectivity could be blocked by anti-VSV or anti-G antiserum. The successful replication, assembly, and budding of DI particles from cells expressing all five VSV proteins from cloned cDNAs provide a powerful approach for detailed structure-function analysis of the VSV gene products in each step of the replicative cycle of the virus.
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PMID:Cells that express all five proteins of vesicular stomatitis virus from cloned cDNAs support replication, assembly, and budding of defective interfering particles. 184 19

The phosphoprotein (P, previously known as NS) genes of vesicular stomatitis virus serotypes New Jersey and Indiana have been cloned in the Escherichia coli expression vector pET-3a. Transcription of P genes in these clones initiated from a phage T7 RNA polymerase promoter, whereas translation was driven by the Shine-Dalgarno sequence and the initiator AUG codon of the T7 gene 10 message. The clones were introduced into an appropriate E. coli strain in which T7 RNA polymerase was expressed under the control of the lac promoter. Under optimal conditions of induction with isopropylthiogalactopyranoside, P protein made in these bacterial strains constituted 5 to 20% of total cellular protein. P protein expressed in bacteria was unphosphorylated and transcriptionally active in an in vitro reconstitution assay with viral L protein and an N-RNA template. However, the P protein was phosphorylated in vitro by the kinase activities associated with L and the N-RNA template.
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PMID:Cloning and expression of the vesicular stomatitis virus phosphoprotein gene in Escherichia coli: analysis of phosphorylation status versus transcriptional activity. 184 4

Replication and amplification of RNA genomes of defective interfering (DI) particles of vesicular stomatitis virus (VSV) depend on the expression of viral proteins and have until now been attained only in cells coinfected with helper VSV. In the work described in this report, we used a recombinant vaccinia virus-T7 RNA polymerase expression system to synthesize individual VSV proteins in cells transfected with plasmid DNAs that contain cDNA copies of the VSV genes downstream of the T7 RNA polymerase promoter. In this way, we were able to examine the ability of VSV proteins, individually and in combination, to support DI particle RNA replication. VSV proteins were synthesized soon after transfection in amounts that depended on the amount of input plasmid DNA and at rates that remained constant for at least 16 h after transfection. When cells expressing the nucleocapsid protein (N), the phosphoprotein (NS), and the large polymerase protein (L) of VSV were superinfected with the DI particles, rapid and efficient replication and amplification of DI particle RNA was observed. Omission of any one of the three viral proteins abrogated the replication. The maximum levels of DI particle RNA replication that were achieved in the system exceeded those seen with wild-type helper VSV by 8- to 10-fold and were observed at molar L:NS:N protein ratios of approximately 1:200:200. This replication system can be used for analysis of structure-function relationships of VSV proteins that are involved in RNA replication and has potential for use in the identification of RNA sequences in the viral genome that control transcription and replication of VSV RNA.
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PMID:Replication and amplification of defective interfering particle RNAs of vesicular stomatitis virus in cells expressing viral proteins from vectors containing cloned cDNAs. 215 55


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