Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A toluene-permeabilized cell system was established to examine the transcription of certain RNAs regulated during the cell cycle in Chlamydomonas reinhardi. The incorporation of [alpha-32P]UTP into RNA which hybridizes to specific cloned cDNA, such as beta-tubulin, indicates that the cell cycle pattern of RNA accumulation may be controlled, in part, by differential transcription.
Mol Cell Biol 1983 Aug
PMID:Analysis of transcription during the cell cycle in toluenized Chlamydomonas reinhardi cells. 662 39

The synergistic effects of potential amino donors were studied in the assay of CTP synthetase in extracts of Chinese hamster fibroblasts. We found that L-glutamine was not effective as the sole amino donor, but combinations of L-glutamine with NH4HCO3, L-arginine or potassium phosphate did result in the conversion of UTP to CTP. L-arginine or potassium phosphate were also not effective when used alone, and NH4HCO3 was only slightly effective. Our studies demonstrate that the individual synergistic combinations were not additive; multiple combinations of components decreased rather than increased the formation of CTP. The synergistic combinations of L-glutamine with either NH4HCO3 or L-arginine had an absolute requirement for ATP; when ATP and PEP were absent no conversion of UTP to CTP occurred. The presence of GTP in a reaction mixture slightly increased the formation of CTP when L-glutamine and NH4HCO3 were used and substantially increased CTP formation when L-glutamine and L-arginine were used. De novo CTP synthesis was greatly reduced when nonradioactive CTP was added to an assay mixture, suggesting feedback inhibition. A TLC procedure has been developed that allows for the direct separation of UTP and CTP without requiring prior conversion to the mononucleotide or nucleoside level.
Mol Cell Biochem 1983
PMID:Apparent synergism between amino donors for CTP synthesis in Chinese hamster fibroblasts. 665 47

When adenovirus type 5-infected HeLa cells were exposed to the tumor promoter 12-O-tetradecanoyl-phorbol-13-acetate, short pulse-labeling with [3H]uridine in vivo and [3H]UTP incorporation by isolated nuclei in vitro were both consistent with a decreased latent period before initiation by RNA polymerase at early viral promoters. Acceleration was not dependent upon concurrent protein synthesis and could not be attributed to rapid entry of virus into the cell nucleus. 12-O-tetradecanoyl-phorbol-13-acetate suppressed the transcription-delay phenotype of the E1a mutant, hr1, without restoring its ability to replicate.
Mol Cell Biol 1984 Mar
PMID:Accelerated onset of viral transcription in adenovirus-infected HeLa cells treated with the tumor promoter 12-O-tetradecanoyl-phorbol-13-acetate. 671 33

The affinity labeling of E. coli RNA polymerase by periodate-oxidized uridin triphosphate (o-UTP) has been carried out under the conditions of poly(dA) and poly(dT) transcription. The extent of RNA polymerase labeling proved to be 2.5 times higher under the transcription of poly(dA) as compared to poly(dT). The amount of o-UTP attached to beta beta'-subunits has been found to decrease if RNA polymerase is labeled in the transcribed complex with poly(dT). These results as well as those obtained in our previous study (1), suggest that there are two types of binding sites for nucleoside triphosphates and their analogs in E. coli RNA polymerase.
Mol Biol Rep 1980 Mar 31
PMID:Detection of nucleoside triphosphate binding sites of two types in Escherichia coli RNA-polymerase by affinity labeling. 699 17

Characteristics of NTP gamma-anilidates (AnpppN) as substrates of E. coli RNA-polymerase have been studied. Michaelis constants for AnpppN are about an order of magnitude greater than those for the usual substrates, whereas the maximum rates differ but unsignificantly. AnpppA is almost completely transformed to polyA and Anppi when synthesis of polyA takes place with AnpppA as the only substrate with denatured DNA as template (reiteration system). The AnpppA-residue is present at the 5'-terminus of RNA synthesized from AnpppA, CTP, UTP and GTP on T7 DNA template by the holo-enzyme.
Mol Biol (Mosk)
PMID:[Gamma-anilides of nucleoside-5'triphosphates as substrates of DNA-dependent RNA-polymerase of Escherichia coli]. 699 30

Using the model of a primitive earth evaporation pond, the synthesis of three histidyl peptides in yields up to 11% was demonstrated when aqueous solutions of histidine, leucine, ATP, cyanamide, and MgCl2 were evaporated and heated for 24 h at 80 degrees C. In addition, peptides were formed in yields of up to 56%, 35%, and 21%, respectively for phenylalanine, leucine, and alanine when aqueous solutions of the appropriate amino acid were evaporated and heated with cyanamide and one or more of the following components: ATP, AMP, 4-amino-5-imidazole carboxamide, or MgCl2. The greatest peptide yield occurred at pH 3. But peptide formation was demonstrated for a system of Leu, cyanamide, and MgCl2 adjusted to pH 7 with NH4OH. Peptide synthesis was also studied in the presence of CaCl2, ZnCl2, different adenosine nucleotides, and UTP to compare their effects on peptide synthesis. The optimum conditions for cyanamide mediated peptide synthesis were also studied in terms of pH, reaction time, reaction temperature, and cyanamide concentration. The major side product in nearly all reactions studied appears to be an amino acid-cyanamide adduct. Peptides were analyzed and identified by thin layer chromatography, acid hydrolysis, and enzymatic degradation.
J Mol Evol 1981
PMID:Cyanamide mediated syntheses of peptides containing histidine and hydrophobic amino acids. 727 11

Reiterative transcription is the repetitive addition of nucleotides to the 3' end of a nascent transcript due to slippage between the transcript and DNA template. Recently, we showed that pyrimidine-mediated regulation of pyrBI operon expression in Escherichia coli occurs, in part, through a mechanism in which induction of UTP-dependent reiterative transcription within the initially transcribed region prevents downstream extension of the nascent transcript to include structural gene sequences. In this study we demonstrate that pyrimidine-mediated regulation of codBA operon expression in E. coli also involves UTP-dependent reiterative transcription during initiation; however, the mechanism is different from that of the pyrBI operon. The initially transcribed region of the codBA promoter contains the sequence GATTTTTTG (non-template strand). Our results show that transcription is initiated primarily at the first two bases designated G7 and A8 (counting from the -10 region). When transcripts are initiated at position A8, UTP-dependent reiterative transcription always occurs within the run of T residues in the initially transcribed region. The AUUUUn (where n = 1 to > 15) transcripts produced by this reaction are not extended productively to include downstream codBA sequences. In contrast, most transcripts initiated at position G7 do not engage in reiterative transcription and can be elongated normally. Characterization of a codBA promoter mutation that prevents reiterative transcription showed that this reaction is required for virtually all pyrimidine-mediated regulation of operon expression and that UTP levels control the selection of the G7 and A8 transcriptional start sites. These results suggest a model for regulation in which high intracellular levels of UTP favor transcriptional initiation at position A8 and thus the accompanying reiterative transcription, which together preclude initiation at position G7. Low levels of UTP inhibit initiation at position A8 and the associated reiterative transcription, thereby allowing high levels of initiation at position G7 and operon expression. Our results also indicate critical sequence requirements for reiterative transcription, which are important for understanding the mechanism of this reaction as well as for identifying other promoters at which this reaction may occur. Of particular interest is the indication that an RNA:DNA hybrid forms during transcriptional initiation and the strength of this hybrid controls the extent of reiterative transcription.
J Mol Biol 1995 Dec 08
PMID:Regulation of codBA operon expression in Escherichia coli by UTP-dependent reiterative transcription and UTP-sensitive transcriptional start site switching. 750 Mar 33

Regulation of transcription involves numerous specific protein-nucleic acid interactions. We have utilized photochemical crosslinking to identify interactions between Escherichia coli transcription proteins and the nascent RNA in several transcription complexes, including initiation, elongation, and antitermination complexes. We have developed new nucleotide analogs, 5-APAS-UTP and 5-APAS-CTP, which are tagged with photocrosslinking groups on base positions that do not interfere with normal Watson-Crick base-pairing. These analogs are incorporated at internal positions in RNA by E. coli RNA polymerase without disrupting RNA secondary structures. We have also used 8-azido-ATP, which can be incorporated uniquely into the 3' end of the RNA, to analyze interactions at the enzyme active site. Interactions between the RNA and the polymerase subunits, and the effect of various transcription factors, including NusA, NusB, NusE, and NusG, have been examined in complexes containing RNAs from 4 to approximately 80 nucleotides. At almost every RNA position examined, both the beta and beta' subunits are contacted, but never the alpha subunit or NusA. An effect of NusA on the core labeling has been observed in some complexes, however. Sigma is contacted by nucleotides within three nucleotides of the +1 position on the DNA.
Cell Mol Biol Res 1993
PMID:Photocrosslinking analysis of protein-RNA interactions in E. coli transcription complexes. 750 93

One of the potential regulatory steps in procaryotic transcription is promoter clearance, a transition step in transcription initiation at which an RNA polymerase (RNAP) switches from the initial transcribing stage to the elongation stage. The biological significance of promoter clearance and the role of RNAP in this process are not understood. One approach to address these questions is to study mutant RNAPs that have altered promoter clearance. Because the antibiotic rifampicin inhibits transcription by preventing an initial transcribing complex from entering the elongation mode, mutant RNAPs which confer rifampicin (Rifr) are likely to be altered in promoter clearance. To test this hypothesis, we studied the effects of Rifr RNAPs on the pyrBI promoter, which is subject to control of promoter clearance in response to the availability of UTP. Two Rifr alleles that carry a different altered amino acid residue at position 529 of the beta subunit appeared to be defective in transcription from the pyrBI promoter in vivo. Biochemical analysis of one of these mutant RNAPs, RpoB3401 with a R529C change in the beta subunit, showed that it overproduces aborted initiation products from the pyrBI promoter and thus is defective in promoter clearance leading to reduced productive initiation. The severity of overproducing the aborted initiation products is an inverse function of the UTP concentration indicating that RpoB3401 has reduced affinity for UTP and thus is subject to a high Km barrier during promoter clearance. The defect of RpoB3401 in abortive initiation in vitro could account fully for its reduced initiation activity in vivo demonstrating the biological significance of abortive synthesis in transcription initiation. Our results indicate that at least part of the "rif region" is important for the process of abortive initiation and that promoter clearance can be regulated in part by modulating the Km of RNAP for nucleotides during initiation. The mutant enzyme is not altered in stuttering RNA synthesis at the pyrBI promoter, previously observed with wild-type RNAP. Our results also show that the mechanisms underlying the two non-productive initiation events (abortive synthesis and stuttering synthesis) at the pyrBI promoter are distinct.
J Mol Biol 1994 Feb 11
PMID:An Escherichia coli RNA polymerase defective in transcription due to its overproduction of abortive initiation products. 750 86

The ATP signaling mechanism in neuroblastoma x glioma hybrid NG108-15 cells differentiated by exposure to dibutyryl-cAMP was characterized. In cells loaded with fura-2, ATP rapidly raised the cytosolic Ca2+ concentration ([Ca2+]i); the magnitude of the rise was inversely proportional to the extracellular Na+ concentration. Large increases in cytosolic Na+ concentration, measured with the fluorescent Na+ indicator sodium-binding benzofuran isophthalate, were dose-dependently elicited by ATP. ATP also evoked the entry of ethidium bromide into cells, and this process was inhibited by Mg2+. Inositol-1,4,5-trisphosphate (IP3) generation induced by ATP was totally blocked by removal of extracellular Ca2+, but residual IP3 generation still remained in nondifferentiated cells. In addition, ATP produced a concentration-, time-, and Mg(2+)-dependent biphasic uptake of 45Ca2+. A range of nucleotides and ATP analogues, including CTP, UTP, and GTP, induced only 9-29% of the ATP response. However, adenosine 5'-thiotriphosphate evoked 79% of ATP-induced 45Ca2+ uptake. 45Ca2+ uptake elicited by ATP could be potently blocked by purinoceptor antagonists, but other tested reagents less effectively blocked the action of ATP. When bradykinin was used as an agonist, the [Ca2+]i rise was transient and was insensitive to the extracellular Na+ concentration. Na+ influx, entry of ethidium bromide, and 45Ca2+ uptake were unaffected by bradykinin. Furthermore, bradykinin-evoked IP3 generation was insensitive to extracellular Ca2+. Neither ATP nor bradykinin had any effect on cAMP levels within cells. These data suggest that ATP induces a [Ca2+]i rise in differentiated NG108-15 cells via two distinct Ca2+ influx mechanisms, i.e., a receptor-operated cation channel and pores formed by ATP4-. These mechanisms are distinct from those elicited by bradykinin.
Mol Pharmacol 1994 Mar
PMID:Two distinct ATP signaling mechanisms in differentiated neuroblastoma x glioma hybrid NG108-15 cells. 751 80


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