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Query: UNIPROT:P06889 (Mol)
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A 2.4 kb cDNA clone containing the coding sequence for glutamine synthetase (GS) was isolated from a rat brain cDNA library, and a probe constructed from this cDNA was utilized in Northern analysis of total RNA to study the tissue distribution and the ontogeny of GS mRNA expression in the rat brain from embryonic day 14 (E14) to adulthood. The levels of GS mRNA were highest in the brain, followed by kidney and liver. In the brain, the GS message was detected as early as E14, earlier than it can be detected by either enzymatic assays of GS activity or by immunocytochemical localization of GS. The relatively low levels of GS mRNA seen at E14 increase to a peak around the time of birth, and in the second postnatal week another rise in GS message occurs approaching adult levels by P15. Localization of GS to astrocytes in the brain was confirmed using both immunocytochemistry and in situ hybridization.
Brain Res Mol Brain Res 1989 Dec
PMID:The ontogeny and localization of glutamine synthetase gene expression in rat brain. 257 2

We have determined the DNA sequence of a Rhizobium meliloti gene that encodes glutamine synthetase II (GSII). The deduced amino acid sequence was compared to that of Bradyrhizobium japonicum GSII and those of various plant and mammalian glutamine synthetases (GS) in order to evaluate a proposal that the gene for this enzyme was recently transferred from plants to their symbiotic bacteria. There is 83.6% identity between the R. meliloti and B. japonicum proteins. The bacterial GSII proteins average 42.5% identity with the plant GS proteins and 41.8% identity with their mammalian counterparts. The plant proteins average 53.7% identity with the mammalian proteins. Thus, the GS proteins are highly conserved and the divergence of these proteins is proportional to the phylogenetic divergence of the organisms from which the sequences were determined. No transfer of genes across large taxonomic gaps is needed to explain the presence of GSII in these bacteria.
J Mol Evol 1989 Nov
PMID:Glutamine synthetase II in Rhizobium: reexamination of the proposed horizontal transfer of DNA from eukaryotes to prokaryotes. 257 72

Glutamine synthetase, purified from Lupinus angustifolius legume nodules, was carboxymethylated and succinylated prior to chemical or enzymatic cleavage. Peptides were purified and sequenced. An oligonucleotide probe was constructed for the sequence MPGQW. This probe was used to identify a glutamine synthetase cDNA clone, pGS5, from a lupin nodule cDNA library constructed in pBR322. pGS5 was sequenced (1043 bp) and computer-assisted homology searching revealed a high degree of conservation between this lupin partial cDNA clone and other plant glutamine synthetases at both the amino acid (greater than 90%) and nucleotide (greater than 80%) level. Northern and Southern analyses using pGS5 supported the conclusion that a multigene glutamine synthetase family exists in lupin which is differentially expressed in both an organ-specific and temporal manner. Western and Northern blot analyses indicated the accumulation of a glutamine synthetase specific mRNA species during nodule development corresponded to the appearance of a novel glutamine synthetase polypeptide between 8 and 10 days after rhizobial inoculation.
Plant Mol Biol 1989 Nov
PMID:The isolation and characterization of a cDNA clone encoding Lupinus angustifolius root nodule glutamine synthetase. 257 95

The heterogeneity of a synaptosomal preparation was studied by the use of affinity partitioning in combination with centrifugal counter-current distribution. Hexaethonium-poly(ethyleneglycol) was used as the extracting agent. The fractions were analyzed for: light scattering, protein, choline acetyltransferase, L-glutamate decarboxylase, glutamine synthetase, 2',3'-cyclicnucleotide-3'-phosphohydrolase, acetylcholinesterase and succinate dehydrogenase. The material was fractionated into three main fractions which differed in their content of marker-enzymes.
Mol Cell Biochem 1989 Jun 01
PMID:Heterogeneity of a crude synaptosomal preparation, studied by affinity partitioning using hexaethonium-poly(ethylene glycol). 277 Jul 19

We have isolated a glutamine synthetase cDNA clone derived from chicken retinal RNA. The clone detects a 3.2-kilobase RNA in chicken retina, liver, and brain, based on Northern blotting analysis. The dramatic developmental rise observed for the retinal enzyme, assayed as glutamyl transferase activity, is accompanied by a corresponding rise in this RNA. Injection of hydrocortisone 21-phosphate into the yolk sac of day 10 embryos produces an increase in retinal glutamine synthetase mRNA and glutamyl transferase activity, assayed 4 days after injection. An increase in glutamine synthetase mRNA is also observed within 2 h of incubation of retinal organ cultures with hydrocortisone. Moreover, incubation of these cultures with cycloheximide at a concentration that inhibits protein synthesis by 93% affects neither the basal level nor the hydrocortisone-mediated induction of glutamine synthetase mRNA. Although expression of this RNA is developmentally regulated in the brain, steroid hormone injection does not result in a substantial induction. Hepatic glutamine synthetase mRNA is expressed constitutively between embryonic day 10 and 6 days after hatching and is also not hormone inducible. Southern blotting data with chicken DNA digested with EcoRI, HindIII, and BamHI are best interpreted in terms of the cDNA clone detecting only one gene. If so, several cell-type-specific regulatory mechanisms must function to modulate expression of this gene during development.
Mol Cell Biol 1987 Mar
PMID:Tissue-specific regulation of avian glutamine synthetase expression during development and in response to glucocorticoid hormones. 288 15

We have investigated the regulation of glutamine synthetase (GS) mRNA synthesis in cultured 3T3-L1 adipocytes. Specific mRNA synthesis (transcription) was analyzed by measuring elongation of transcripts in isolated nuclei. Transcription rate was assayed by hybridization of newly synthesized [32P]RNA to a GS cDNA. GS transcription rate increased more than 100-fold during adipocyte differentiation and was inhibited more than 90% by alpha-amanitin. In 3T3-L1 adipocytes dexamethasone stimulated GS gene transcription while insulin and dibutyryl cAMP decreased GS gene transcription.
Mol Cell Endocrinol 1987 May
PMID:Glutamine synthetase gene transcription in cultured 3T3-L1 adipocytes: regulation by dexamethasone, insulin and dibutyryl cyclic AMP. 288 36

In situ hybridization showed that all fetal hepatocytes contain glutamine synthetase (GS) mRNA but that in adult mouse liver, only a single cell layer surrounding the central veins contains GS mRNA. A shift from the fetal to the adult pattern begins within a few days of birth and is complete within 12 days of birth. Since the total GS mRNA and the transcription rate of the single GS gene are similar at birth and in adults, we conclude that there is a generalized reduction in GS transcription for most hepatocytes and a sharp rise in GS transcription for the immediate pericentral cells. This may be a case of positional regulation of specific gene transcription in apparently a single cell lineage.
Mol Cell Biol 1988 Nov
PMID:Positional and developmental regulation of glutamine synthetase expression in mouse liver. 290 22

The glnB gene of Klebsiella pneumoniae, which encodes the nitrogen regulation protein PII, has been cloned and sequenced. The gene encodes a 12429 dalton polypeptide and is highly homologous to the Escherichia coli glnB gene. The sequences of a glnB mutation which causes glutamine auxotrophy and of a Tn5 induced Gln+ suppressor of this mutation were also determined. The glutamine auxotrophy was deduced to be the result of a modification of the uridylylation site of PII, and the suppression was shown to be caused by Tn5 insertion in glnB. The 3' end of an open reading frame of unknown function was identified upstream of glnB and may be part of an operon containing glnB. Potential homologues of glnB encoding polypeptides extremely similar in sequence to PII were identified upstream of published sequences of the glutamine synthetase structural gene (glnA) in Rhizobium leguminosarum, Bradyrhizobium japonicum and Azospirillum brasilense.
Mol Gen Genet 1988 Dec
PMID:Identification of the Klebsiella pneumoniae glnB gene: nucleotide sequence of wild-type and mutant alleles. 290 69

We have investigated the regulation of glutamine synthetase (GS) mRNA synthesis in Chinese hamster ovary cell mutants which overproduce GS and contain an amplified GS gene. Specific mRNA synthesis was analyzed by measuring elongation of transcripts in isolated nuclei. Transcription was assayed by hybridization of newly synthesized [32P]RNA to a genomic GS clone. Nuclear transcript elongation was inhibited more than 90% by alpha-amanitin. The relative rates of GS mRNA synthesis in nuclei from cells incubated for 2 days with no additions, insulin, dexamethasone, or (Bu)2cAMP are 186, 419, 375, and 227 ppm, respectively. The insulin- and dexamethasone-mediated increases in GS transcription rate (2-fold) were associated with 3.7- and 5.8-fold increases in GS mRNA abundance. By contrast, alpha-tubulin gene transcription was not altered by insulin or dexamethasone; however, it was decreased by (Bu)2cAMP.
Mol Endocrinol 1987 Jun
PMID:Insulin and dexamethasone stimulate transcription of an amplified glutamine synthetase gene in Chinese hamster ovary cells. 290 59

We have cloned alfalfa nodule-specific cDNAs that code for leghemoglobin (Lb), glutamine synthetase (GS), and three unidentified nodulins. Hybrid-select translation of nodule RNA followed by 2-D gel electrophoresis showed that the Lb-specific cDNA corresponded to at least four Lb species of 12 kDa. One of the unidentified cDNA clones (N-32/34) corresponded to at least five polypeptides of 32-34 kDa; a second unidentified cDNA clone (N-14) corresponded to an individual polypeptide of 14 kDa. The in vitro translation product(s) of the RNA hybrid selected by the third unidentified cDNA clone (N-22) formed a single band at 22 kDa on a one-dimensional gel. Northern and dot blot analyses of RNA isolated from wild-type nodules and from defective nodules elicited by a variety of Rhizobium meliloti mutants showed that 1) RNAs corresponding to the Lb, nodule-specific GS, and three unidentified nodulins were coordinately expressed during the course of nodule development, and 2) all five nodulins were expressed in Fix- nodules that contained infection threads and bacteroids but were not expressed in nodules that lacked infection threads and intracellular rhizobia.
Mol Plant Microbe Interact 1988 Feb
PMID:Developmental regulation of nodule-specific genes in alfalfa root nodules. 290 68


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