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

Glutamate dehydrogenase activity was found to be present at a high level in neoplastic cytosol and microsomes, 3.45 and 9.90 nmoles NADH/min mg protein, respectively. This remains in accordance with the high rate of RNA and protein synthesis in the neoplastic process.
Mol Biol Rep 1979 Dec 31
PMID:Glutamate dehydrogenase activity in subcellular fractions of mouse fibrosarcoma. 53 Feb 74

Glutamate induced postsynaptic currents (g-EPSCs) were elicited by 2-5 ms glutamate pulses applied iontophoretically through high resistance (80-200 M Omega) micropipettes. Such g-EPSCs decayed with time constants in the range of 5 ms. The dose-response curves for the action of glutamate were S-shaped with a limiting log log slope of 4-6, the half maximum response concentration of glutamate was about 10(-4) Mol/l and the maximum synaptic current in the range of 30 nA. In pairs of small g-EPSCs following each other with delays between 3 and 100 ms, the second one was potentiated. For short delays potentiation was up to 60 fold. The time course of the g-EPSCs and of their potentiation can be described quantitatively with the following assumptions: 1. The simultaneous reaction of 4-6 glutamate molecules with a receptor triggers postsynaptic current flow. 2. The synaptic glutamate concentration is determined by diffusion from a point source. 3. Potentiation is due to summation of the synaptic glutamate concentrations generated by pulse 1 and by pulse 2. The relevance of these results for the interpretation of the natural EPSC is discussed.
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PMID:Kinetics of postsynaptic action of glutamate pulses applied iontophoretically through high resistance micropipettes. 117 48

Membrane currents were recorded from Xenopus laevis oocytes injected with C. elegans poly(A)+ RNA. In such oocytes glutamate activated an inward membrane current that desensitized in the continued presence of glutamate. Glutamate-receptor agonists quisqualate, kainate, and N-methyl-D-aspartate were inactive. The reversal potential of the glutamate-sensitive current was -22 mV, and exhibited a strong dependence on external chloride with a 48 mV change for a 10-fold change in chloride. The chloride channel blockers flufenamate and picrotoxin inhibited the glutamate-sensitive current. Ibotenate, a structural analog of glutamate, also activated a picrotoxin-sensitive chloride current. Ibotenate was inactive when current was partially desensitized with glutamate, and the responses to low concentrations of glutamate and ibotenate were additive. The anthelmintic/insecticide compound avermectin directly activated the glutamate-sensitive current. In addition, avermectin increased the response to submaximal concentrations of glutamate, shifted the glutamate concentration-response curve to lower concentrations, and slowed the desensitization of glutamate-sensitive current. We propose that the glutamate-sensitive chloride current and the avermectin-sensitive chloride current are mediated via the same channel.
Brain Res Mol Brain Res 1992 Oct
PMID:Expression of a glutamate-activated chloride current in Xenopus oocytes injected with Caenorhabditis elegans RNA: evidence for modulation by avermectin. 127 55

In primary cultures of neurons from cerebral cortex and striatum, 30 s stimulation with the excitatory amino acid glutamate elicited a 5 to 9-fold increase in immediate early gene (IEG) mRNAs. Glutamate increased c-fos, c-jun, jun-B, and NGFI-A (zif/268) mRNAs by binding to both alpha-amino-3-hydroxy-5-methylisoxazolepropionic acid (AMPA) and N-methyl-D-aspartate (NMDA) receptor types, and increased c-fos, jun-B, and NGFI-A mRNAs by binding to the metabotropic receptor. NMDA receptor activation elicited IEG expression by a transmembrane calcium influx; AMPA receptor-induced depolarization played a permissive role for the opening of the NMDA receptor channel. The protein kinase C (PKC) inhibitor H-7 (but not inhibitors of cyclic nucleotide-dependent and calcium/calmodulin-dependent protein kinases) partially blocked IEG expression induced by glutamate.
Brain Res Mol Brain Res 1992 Jan
PMID:Differential induction of immediate early genes by excitatory amino acid receptor types in primary cultures of cortical and striatal neurons. 134 32

[3H]Dextrorphan recognition sites were characterized in rat brain membranes. The pharmacological profile and regional distribution of [3H]dextrorphan binding sites appear to distinguish these sites from those labeled either by [3H]dextromethorphan or by putative sigma receptor radioligands. Data from thoroughly washed forebrain membranes suggest that [3H]dextrorphan predominantly labels a high affinity site defined by the activated state of the N-methyl-D-aspartate (NMDA) receptor-channel complex. Regulation of [3H]dextrorphan binding by specific modulators of NMDA receptor function suggests that [3H]dextrorphan binding is predominantly localized to a domain of the receptor-channel complex also recognized by the prototypical noncompetitive antagonist radioligands (+)-[3H]5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imi ne (MK-801) and [3H]1-[1-(2-thienyl)cyclohexyl]piperidine (TCP). The critical relationship between [3H]dextrorphan binding and activation of the NMDA receptor-complex is suggested by the profound dependence of [3H]dextrorphan binding on glutamate in well washed membranes. Basal specific [3H]dextrorphan binding is nearly totally suppressed by the specific competitive NMDA antagonist D(-)-2-amino-5-phosphonopentanoic acid (D-AP5), in a glutamate- but not glycine-surmountable manner. Glutamate and glycine each stimulate [3H]dextrorphan binding in a concentration-dependent manner, effecting maximal increases from control of up to 30- and 14-fold, respectively. The NMDA receptor specificity of the modulation of [3H]dextrorphan binding by glutamate and glycine is indicated by the sensitivity of their effects to competitive antagonism by D-AP5 and 3-amino-1-hydroxy-2-pyrrolidone (HA-966), respectively, and by the accordant rank orders of potency of glycine analogs as modulators of [3H]dextrorphan binding and as ligands at the strychnine-insensitive glycine site. The divalent cations Mg2+ and Zn2+ and the polyamines spermine and spermidine regulate [3H]dextrorphan binding in a manner consistent with radioligand interaction at the noncompetitive NMDA antagonist domain. Mg2+ and spermidine regulate [3H]dextrorphan binding biphasically in well washed forebrain membranes, whereas Zn2+ monotonically inhibits [3H]dextrorphan binding. Mg2+ and spermidine regulate [3H]dextrorphan binding with qualitative similarity and in a contrasting fashion to their regulation of [3H]MK-801 and [3H]TCP binding. First, spermidine and Mg2+ are significantly more potent modulators of [3H]dextrorphan binding than of [3H]MK-801 and [3H]TCP binding in well washed membranes; second, whereas the potencies of spermidine and Mg2+ as modulators of [3H]MK-801 and [3H]TCP binding are significantly increased by glutamate and glycine in well washed membranes, their potencies as regulators of [3H]dextrorphan binding appear to be unaffected by glutamate and glycine.(ABSTRACT TRUNCATED AT 400 WORDS)
Mol Pharmacol 1992 Jan
PMID:High affinity [3H]dextrorphan binding in rat brain is localized to a noncompetitive antagonist site of the activated N-methyl-D-aspartate receptor-cation channel. 137 Jul 4

In FRTL-5 cells, methimazole (MMI) and propylthiouracil (PTU), both thyroid peroxidase (TPO) inhibitors, increase thyroglobulin (Tg) mRNA levels and Tg accumulation in the medium. An increase in Tg mRNA levels and in Tg accumulation was observed after 2-4 h and 8 h incubation with 10,000 microM MMI or PTU, respectively. Glutamate dehydrogenase mRNA levels, which corresponded with total RNA levels, were not affected. The concentrations of these drugs at which stimulation occurs are higher than the concentrations required for complete inhibition of TPO activity. The stimulatory effects of MMI and PTU can be suppressed by iodide and do not occur when protein synthesis is inhibited by cycloheximide. The effect of MMI on Tg gene expression is not dependent on thyrotropin (TSH) or insulin and MMI does not change the TSH-induced cAMP production. We conclude that MMI and PTU interfere in a regulatory pathway for Tg gene expression.
Mol Cell Endocrinol 1991 Dec
PMID:Methimazole and propylthiouracil increase thyroglobulin gene expression in FRTL-5 cells. 179 3

Glutamate in glutamatergic neurons exists in a cytosolic pool, as well as a transmitter pool, which is assumed to be localized in synaptic vesicles. Transmitter glutamate released from glutamatergic neurons is taken up by both neurons and glial cells, giving rise to a flux of glutamate from neurons to astrocytes. In astrocytes, glutamine is formed from glutamate by the glial-specific enzyme glutamine synthetase (EC 6.3.1.2). Glutamine diffuses back to neurons, where glutamate is formed by phosphate-activated glutaminase (EC 3.5.1.2). However, this cycle is not stoichiometric, and glutamine obtained from glial cells cannot replenish all transmitter glutamate lost from neurons. 2-Oxoglutarate is another putative precursor for transmitter glutamate. Net synthesis of citric acid cycle intermediates is dependent on carbon dioxide fixation to pyruvate, catalyzed by pyruvate carboxylase (EC 6.4.1.1). Since this enzyme is exclusively glial, a net flow of citric acid cycle intermediates from glial cells to neurons probably exists. The quantitative contribution of each transmitter precursor may not be the same in different regions of the brain and may vary with the metabolic state of the neuron. The pool of transmitter glutamate is most likely regulated by the activity of glutamate-forming enzymes in the nerve terminal, and/or by uptake/release of glutamate and glutamate precursors through the synaptosomal plasma membrane.
Mol Chem Neuropathol 1990 Jan
PMID:Synthesis of transmitter glutamate and the glial-neuron interrelationship. 198 May 84

Earlier studies have suggested that glutamate may play an important role in the transition between the mitotic (vegetative) and meiotic (sporulative) stages of the life cycle in the yeast Saccharomyces cerevisiae. Glutamate is also a major excitatory neurotransmitter in the vertebrate brain, and its actions are mediated by the excitatory amino acid (EAA) family of receptors, the three best-characterized of which are the N-methyl-D-aspartate (NMDA), quisqualate (Q), and kainate (K) receptors. As an initial test of the possibility that glutamate action in S. cerevisiae might be mediated by an EAA-like receptor mechanism, the effects of ligands that define the functional domains of the vertebrate NMDA receptor have been examined. The responses of S. cerevisiae cells to ligands that act at four distinct sites on the NMDA receptor provide the first evidence for an NMDA-like receptor-mediated system involved in the control of yeast sporulation.
Mol Microbiol 1990 Oct
PMID:Effects of N-methyl-D-aspartate receptor ligands on yeast sporulation. 198 4

The amino acid pool sizes of Trichomonas vaginalis are reported. Alanine, glutamic acid, proline and leucine account for 72% of the measured amino acids. Growth of T. vaginalis was unaffected by gostatin, an irreversible inhibitor of aspartate aminotransferase, when the enzyme activity within the cell had been completely inhibited and a specific elevation of the aspartate pool had occurred. In media lacking aspartate and glutamate, the amino acid substrates of the aspartate aminotransferase reaction, gostatin caused a larger increase in the aspartate pool. During incubation of cells with or without gostatin, aspartate and glutamate were produced in the medium, presumably by proteolysis of medium proteins. Hence any requirement for the aspartate aminotransferase reaction might have been bypassed. Glutamate-gamma-hydroxamate and aminooxyacetate inhibited growth of T. vaginalis but caused large changes in the pool-sizes of aspartate, glutamate, pyruvate plus oxaloacetate and 2-oxoglutarate, suggesting a more general interference with amino acid metabolism.
Mol Biochem Parasitol 1986 Oct
PMID:Modulation of amino acid and 2-oxo acid pools in Trichomonas vaginalis by aspartate aminotransferase inhibitors. 287 95

Effects of glutamate on myocardial mechanical function and energy metabolism during 120 min of hypoxia and subsequent reoxygenation were studied in the isolated arterially perfused newborn and adult rabbit hearts. The muscle was perfused with a Krebs-Henseleit (KH) solution or KH solution which contained 1 mM glutamate. Glutamate attenuated the effects of hypoxia on mechanical function and tissue ATP concentration, and enhanced the recovery of mechanical function and tissue ATP during reoxygenation. During hypoxia, glutamate increased tissue succinate and GTP with no change in total lactate and pyruvate production. Trace studies using 14C-glutamate and the tissue homogenate showed that hypoxia increased tissue succinate and inhibited TCA cycle. Additional glutamate produced more CO2 and TCA intermediates in both oxygenated and hypoxic mediums. These data indicate that glutamate increased the rate of ATP production in the hypoxic and reoxygenated heart. This study shows that the improvement of mechanical function and ATP formation in the hypoxic myocardium by glutamate was due to an increase in both oxidative phosphorylation and substrate level phosphorylation. The effect of glutamate on the ATP and GTP production in the newborn heart was not different from the adult.
J Mol Cell Cardiol 1986 Sep
PMID:The effect of glutamate on hypoxic newborn rabbit heart. 287 83


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