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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Two clones from the Clarke-Carbon Escherichia coli colony bank were resistant to inhibition by trimethoprim, a potent inhibitor of dihydrofolate reductase. Both clones had elevated levels of dihydrofolate reductase. Furthermore, trimethoprim resistance and elevated enzyme levels were associated with ColE1 plasmids that carried DNA from the trkC ksgA pdxA region of the E. coli chromosome. Plasmid pLC1437a was shown by two criteria to carry the structural gene for dihydrofolate reductase: 1) A partial diploid containing plasmid pLC1437a produced a kinetically-recognizable dihydrofolate reductase that was not present in the parent haploid strain. 2) Plasmid pLC1437a coded for dihydrofolate reductase in vitro. A 1,000 base pair fragment of plasmid pLC1437a containing fol was used as a probe to measure fol mRNA in a mutant strain isolated by Sheldon and Brenner (Molec. gen. Genet. 147, 91-97, 1976). The mutation in this strain, which results in constitutively-high levels of dihydrofolate reductase and in the inability of the strain to grow at 42 degrees C, is cis dominant (Sheldon and Brenner, 1976). The results of kinetic hybridization and pulse-labeling experiments indicated that the regulatory mutant produced elevated levels of dihydrofolate reductase in response to an increased rate of synthesis of fol mRNA.
Mol Gen Genet 1979 Aug
PMID:Regulation of dihydrofolate reductase synthesis in Escherichia coli. 39 Mar 4

A 1,2,4-triazole resistant mutant of S. typhimurium has been isolated, in which serine transacetylase activity is seven times higher than in wild type. Partially purified serine transacetylase from a strain carrying the trz-312 mutation has kinetic properties which are virtually identical to those of the wild type enzyme and binds to O-acetylserine sulfhydrylase A to form a cysteine synthetase complex which is also indistinguishable from that found in wild type. Thus the increased activity of serine transacetylase associated with trz-312 appears to result from increased quantities of a kinetically normal, enzyme protein. Resistance to 1,2,4-triazole is probably due to the ability of trz-312 strains to synthesize O-acetyl-L-serine at a rapid enough rate to compensate for that utilized by the O-acetylserine triazolylase reaction. Genetic mapping experiments, using P1-mediated transduction, show that trz-312 is 91-99% linked to cysE, the structural gene for serine transacetylase. The results of three point crosses indicate that this mutation is located at one extreme end of the cysE locus, as would be expected for a promotor mutation.
Mol Gen Genet 1976 Oct 18
PMID:A mutation affecting expression of the gene coding for serine transacetylase in Salmonella typhimurium. 79 Jan 54

The incorporation of 32P into well washed human erythrocyte membranes was studied in a medium containing [gamma-32P]ATP, Mg2+, and EGTA. Following phosphorylation, the membranes were completely solubilized in 1% sodium dodecyl sulfate and subjected to gel electrophoresis in dodecyl sulfate polyacrylamide. A large incorporation of radioactivity was observed in a band which migrated faster than component 7 (nomenclature of T. L. Steck, (1972), J. Mol. Biol. 66, 295) but slower than the bromophenol blue tracking dye, and did not stain with Coomassie Blue. Isolation of this band by preparative gel electrophoresis revealed that 41% of the radioactivity was associated with a 32P-labeled polypeptide. This polypeptide was further purified by gel chromatography on Sephadex LH-20 in chloroform-methanol-HCl, and Bio-Gel A 1.5m in dodecyl sulfate. Its amino acid composition is characterized by a high content of acidic residues. The calculated minimal molecular weight is 15084. Based upon the recovery of amino acids, the polypeptide fraction comprises at least 1.8% by weight of the total erythrocyte membrane proteins. An apparent molecular weight of 15000 was estimated by gel chromatography in dodecyl sulfate, while a range of 14000-16000 was estimated by electrophoresis in dodecyl sulfate polyacrylamide. The state of phosphorylation of this peptide may reflect a physiological function in the intact red cell.
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PMID:Isolation of a 32P-labeled polypeptide of low molecular weight from phosphorylated human erythrocyte membranes. 124 9

A 1.45 kb DNA sequence encoding the rat alpha 6 GABAA receptor subunit (nucleotides 33-1483) was cloned from a Sprague-Dawley rat brain cDNA library by PCR amplification. Dideoxy sequencing of two individual clones revealed that the nucleotide sequence differed at only one basepair (T480-->G) from that published previously. This difference altered the deduced amino acid sequence, producing a conservative amino acid substitution (His121-->Gln). A Gln residue is present at the same location in the bovine alpha 6 subunit. Restriction endonuclease analysis of the total PCR product demonstrated that this variant of the rat alpha 6 subunit was the only allele found in this particular rat brain library, the original allele was not present. These results were further verified by RNAse protection assays performed with RNA isolated from individual rat cerebella. alpha 6, beta 1, and gamma 2S subunits were transiently expressed in L929 cells for electrophysiological analysis. Whole-cell recordings obtained from the cells demonstrated that GABAA receptor channels with the expected GABA and benzodiazepine pharmacology were produced. Excised outside out single channel recordings from the same cells revealed that GABA elicited brief duration openings to a 33 pS main conductance level and to at least one smaller (approximately 21 pS) subconductance level. Thus this allelic variant of rat alpha 6 subunit could assemble with other subunits to form a functional GABAA receptor channel with similar properties to the original allelic form.
Brain Res Mol Brain Res 1992 Nov
PMID:Molecular and electrophysiological characterization of a allelic variant of the rat alpha 6 GABAA receptor subunit. 128 Dec 55

A nonrandom chromosomal translocation breakpoint, t(15;17)(q22;q21), is found in almost all patients with acute promyelocytic leukemia (APL). Most of these breakpoints occur within the second intron of the retinoic acid receptor-alpha (RARA) gene. We screened a cDNA library of APL and have identified and sequenced a cDNA transcribed from the t(15;17) translocation breakpoint. The 5' end of cDNA p1715 consists of 503 bp of the RARA exon II sequence. A 1.76-kb cDNA without homology to any known gene available in GenBank was found truncated downstream. This cDNA sequence was assigned to chromosome 15 by dot blot hybridization of the flow cytometry-sorted chromosomes. We designate this fusion cDNA RARA/myl, which is different from myl/RARA reported by de The et al. (H. de The, C. Chomienne, M. Lanotte, L. Degos, and A. Dejean, Nature (London) 347:558-561, 1990). This result demonstrates that the two different types of hybrid mRNA can be transcribed from this breakpoint. We screened a non-APL cDNA library and identified a 2.8-kb myl cDNA. This cDNA is able to encode a polypeptide with a molecular weight of 78,450. Alternative splicing of the myl gene which resulted in myl proteins with different C terminals was found. Southern blot analysis of the genomic DNA isolated from 17 APL patients by using the myl DNA probe demonstrated that the myl gene in 12 samples was rearranged. Northern (RNA) blot analysis of RARA gene expression in two APL RNA samples showed abnormal mRNA species of 4.2 and 3.2 kb in one patient and of 4.8 and 3.8 kb in another patient; these were in addition to the normal mRNA species of 3.7 and 2.7-kb. The myl DNA probe detected a 2.6-kb abnormal mRNA in addition to the normal mRNA species of 3.2, 4.2, and 5.5 kb. Using the polymerase chain reaction, we demonstrated that both RARA/myl and myl/RARA were coexpressed in samples from three different APL patients. From this study, we conclude that the t(15;17) translocation breakpoint results in the transcription of two different fusion transcripts which are expected to be translated into fusion proteins.
Mol Cell Biol 1992 Feb
PMID:Characterization of a fusion cDNA (RARA/myl) transcribed from the t(15;17) translocation breakpoint in acute promyelocytic leukemia. 131 Jan 53

A new Escherichia coli mutant named dnaR, which was temperature sensitive in initiation of DNA replication, has been characterized through identification of the mutant gene. A 1.65 x 10(3) base-pair chromosomal DNA fragment isolated from wild-type cells, but not the corresponding fragment from the dnaR mutant, exhibited an activity that reversed temperature-sensitive growth of the mutant. The DNA fragment was found to include the entire prs-coding sequence and specify a 34,000 M(r) protein with phosphoribosylpyrophosphate synthetase activity. The dnaR mutation resided within the prs-coding segment and made the synthetase thermolabile. The coding segment for the dnaR product was determined, by introduction of various mutations into the cloned fragment, to be the same as that for the synthetase. The dnaR function of the prs gene product in DNA replication is discussed on the basis of an observation that thermal treatment of the dnaR mutant caused a delay in initiation of chromosome replication after the downshift, despite the presence of the synthetase activity at the preheat level.
J Mol Biol 1992 Aug 20
PMID:dnaR function of the prs gene of Escherichia coli in initiation of chromosome replication. 132 64

We have isolated the gonadotropin-releasing hormone receptor (GnRH-R) from a rat anterior pituitary cDNA library, determined its sequence and demonstrated receptor function. The 2.2 kb rat GnRH-R clone encodes a protein of 327 amino acids. A 1.3 kb clone encoding the mouse GnRH-R has previously been described (Tsutsumi et al., 1992). Although both the mouse and rat protein share significant homology with molecules belonging to the family of G protein-coupled receptors, they have certain unusual features, an example being the complete absence of a COOH terminal tail. The 3'-untranslated region reported missing in the mouse is present in the rat cDNA, where an extended 1 kb of 3'-untranslated region extending to the poly-A tail is shown. At the amino acid level, the rat GnRH-R shows considerable homology with that of the mouse. Electrophysiological studies with Xenopus oocytes and transfection of the cDNA into COS-1 cells, have shown that the 2.2 kb cDNA clone encodes a functional receptor.
Mol Cell Endocrinol 1992 Dec
PMID:Molecular cloning and characterisation of the rat pituitary gonadotropin-releasing hormone (GnRH) receptor. 133 27

Five purine auxotrophic mutants of Lactococcus lactis were isolated. L. lactis was capable of converting adenine, guanine and hypoxanthine to AMP, GMP and IMP, respectively, indicating the existence of adenine phosphoribosyltransferase (APRT) and hypoxanthine guanine phosphoribosyltransferase (HGPRT) activities. A 1.3 kb DNA fragment from L. lactis was cloned by complementation of the hpt mutation in Escherichia coli. Introduction of this fragment into L. lactis resulted in an increase in HGPRT activity. In vitro transcription and translation analysis showed that the fragment coded for a polypeptide with M(r) of 22,000. The nucleotide sequence of this hpt gene was determined.
Mol Gen Genet 1992 Nov
PMID:Isolation of purine auxotrophic mutants of Lactococcus lactis and characterization of the gene hpt encoding hypoxanthine guanine phosphoribosyltransferase. 146 8

A new protein kinase gene [called NPK1 (for nonessential protein kinase)] has been found on chromosome I of Saccharomyces cerevisiae between CDC15 and ADE1. The 435 amino acid/48 kDa gene product is very similar to known protein kinases. It is most closely related to the nimA protein of Aspergillus nidulans, displaying 45.9% identity and 63.5% similarity in the protein kinase domain. A 1.4 kb transcript of the NPK1 gene was detected. Disruption of the NPK1 gene impedes neither growth on glucose or a variety of other carbon sources, nor mating or sporulation.
Mol Gen Genet 1992 Jul
PMID:NPK1, a nonessential protein kinase gene in Saccharomyces cerevisiae with similarity to Aspergillus nidulans nimA. 149 80

In order to better understand the regulation of Pseudomonas aeruginosa flagellin expression we cloned the sigma factor of RNA polymerase used to transcribe the flagellin gene. It is a member of the sigma 28 class of alternative sigma factors described in several bacterial genera. Using the published sequence of the fliA gene encoding the sigma 28 from Salmonella typhimurium, we designed two oligonucleotides and, using the polymerase chain reaction, isolated the fliA gene from S. typhimurium chromosomal DNA. This heterologous probe was used in the DNA blot analysis of restriction digests of P. aeruginosa DNA. A 1.7 kb SalI-EcoRI fragment reacted with the probe and this fragment was cloned into the pBluescript vectors. The P. aeruginosa fliA gene was able to complement the motility defect of an Escherichia coli fliA mutant, but only when transcription was driven from the vector promoter. Insertional inactivation of the fliA gene with a gentamicin gene cassette rendered P. aeruginosa nonmotile and unable to express the flagellin gene. The 1.7 kb cloned fragment was sequenced and shown to contain the entire fliA gene. P. aeruginosa FliA shares 67% amino acid similarity with the homologous S. typhimurium sequence. Transcriptional analysis of the fliA gene showed that its expression was not dependent on RpoN, a sigma factor shown also to be required for flagellin synthesis. A reading frame downstream of fliA was found to encode the P. aeruginosa homologue of the enterobacterial cheY gene.
Mol Microbiol 1992 Feb
PMID:The fliA (rpoF) gene of Pseudomonas aeruginosa encodes an alternative sigma factor required for flagellin synthesis. 156 Jul 74


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