Renal glutamine synthetase catalyzes the reaction of NH4+ with glutamate, forming glutamine and decreasing the ammonia available for net acid excretion. The purpose of the present study was to determine glutamine synthetase's specific cellular expression in the mouse kidney and its regulation by hypokalemia, a common cause of altered renal ammonia metabolism. Glutamine synthetase mRNA and prote...

BACKGROUND/AIMS It has been proposed that, in acute liver failure, skeletal muscle adapts to become the principle organ responsible for removal of blood-borne ammonia by increasing glutamine synthesis, a reaction that is catalyzed by the cytosolic ATP-dependent enzyme glutamine synthetase. To address this issue, glutamine synthetase expression and activities were measured in skeletal muscle of ...

In certain lines of hepatoma tissue-culture cells, the extracellular glutamine concentration regulates the specific activity of glutamine synthetase. By quantifying the radioactivity in immunoprecipitated glutamine synthetase on polyacrylamide gels, we found that the rate of degradation, but not of synthesis, of glutamine synthetase is a sensitive function of extracellular glutamine. The activi...

Mycobacterium tuberculosis and other pathogenic mycobacteria export abundant quantities of proteins into their extracellular milieu when growing either axenically or within phagosomes of host cells. One major extracellular protein, the enzyme glutamine synthetase, is of particular interest because of its link to pathogenicity. Pathogenic mycobacteria, but not nonpathogenic mycobacteria, export ...

We have examined three mutants of Klebsiella aerogenes whose genetic lesions (glnB, glnD, and glnE) are in loci unlinked to the structural gene for glutamine sythetase (glnA) and in which the control of both the level and state of adenylylation of glutamine synthetase is altered. Each mutation alters a different component of the adenylylation system of glutamine synthetase [L-glutamate:ammonia ...

Glutamine synthetase purified to apparent homogeneity from Bacillus subtilis is subject to feedback inhibition by multiple end products of glutamine metabolism, as well as by the reaction product L-glutamine. AMP, glutamine, and histidine are potent inhibitors when any of the substrates glutamate, MnATP, or ammonia are present in limiting concentration during assay, but the strong inhibition by...

Twenty-four h after tumor transplantation increases of free glutamine in plasma, liver, and kidney occurred simultaneously with the exponential phase of tumor growth. Kidney and muscle glutamine synthetase also increased in the first 2 days following tumor transplantation, while kidney and liver glutaminases decreased. The levels of free glutamine in plasma and tissues, and the activities of gl...

As the initial aspect of investigations on the regulation of glutamine synthetase in rat hepatomas and in hepatoma cell culture systems, glutamine synthetase from rat liver was purified to apparent homogeneity. A single protein band is found in gels after electrophoresis in three separate systems, and a constant enzyme specific activity is found in fractions containing glutamine synthetase acti...

Glutamine establishes feedback control of glutamine synthetase (EC 6.3.1.2) in Escherichia coli over a novel loop, viz. by its effect on an enzymatic adenylylation of glutamine synthetase, whose activity is thus modulated. Positive effecters of the adenylyl transfer reaction, magnesium ion and glutamine, increase the number of -SH groups in adenylyltransferase (EC 2.7.7. -) titratable by 5,5’-d...