Abstract
Calcium stimulates the hydrolysis of glutamine in synaptosomes prepared from rat brain both by the sucrose- (12) and the Ficoll/sucrose-gradient techniques (13). The calcium activation is phosphate-dependent and maximal effect is obtained at a calcium concentration of 0.5–1.0 mM. It is reduced by increasing the numbers of synaptosomes in the incubation mixture, and abolished by the product inhibitors of glutaminase, glutamate and ammonia, but unaffected by the uncoupler 2,4-dinitrophenol which inhibits the mitochondrial proton pump. Moreover, since the hydrolysis of glutamine is mediated by glutaminase (EC 3.5.1.2), and calcium does not activate the purified enzyme, an indirect phosphate-dependent effect of calcium on glutaminase is most likely. Calcium activates preferentially the N-ethylmaleimide insensitive fraction of glutaminase. The calcium activation is not dependent on synaptosomal membranes as it is found in synaptosomes subject to previous freezing. It is also found in isolated synaptosomal mitochondria and is thus a property of nerve endings. The calcium activation of glutaminase is unaffected by potassium in depolarizing concentrations, and may not be directly involved in the neurotransmission processes, but possibly in replenishing depleted stores of transmitter glutamate.
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Abbreviations
- NEM:
-
N-ethylmaleimide
- PAG:
-
phosphate-activated glutaminase
References
Bradford, H. F., Ward, H. K., andThomas, A. J. 1978. Glutamine—a major substrate for nerve endings. J. Neurochem. 30:1453–1459.
Hamberger, A. C., Chiang, G. H., Nylén, E. S., Scheff, S. W., andCotman, C. W. 1979. Glutamate as a CNS transmitter. I. Evaluation of glucose and glutamine as precursors for the synthesis of preferentially released glutamate. Brain Res. 168:513–530.
Reubi, J. C., Van den Berg, C. J., andCuénod, M. 1978. Glutamine as precursor for the GABA and glutamate transmitter pools. Neurosci. Lett. 10:171–174.
Tapia, R., andGonzález, R. M. 1978. Glutamine and glutamate as precursors of the releasable pool of GABA in brain cortex slices. Neurosci. Lett. 10:165–169.
Kvamme, E., andSvenneby, G. 1975. Phosphate activated glutaminase in brain. Pages 277–290,in Marks, N., andRodnight, R. (eds.), Research Methods in Neurochemistry, Vol. 3. Plenum Press, New York.
Kvamme, E. 1979. Regulation of glutaminase and its possible implication for GABA metabolism. Pages 111–138,in Mandel, P., andDE Feudis, F. V. (eds.), GABA—Biochemistry and CNS Functions, Plenum Press, New York.
Kvamme, E., andLenda, K. 1982. Regulation of glutaminase by exogenous glutamate, ammonia and 2-oxoglutarate in synaptosomal enriched preparation from rat brain. Neurochem. Res. 7:667–678.
Kvamme, E., andOlsen, B. E. 1979. Evidence for two species of mammalian phosphate-activated glutaminase having different regulatory properties. FEBS Lett. 107:33–36.
Benjamin, A. M. 1981. Control of glutaminase activity in rat brain cortex in vitro: Influence of glutamate, phosphate, ammonium, calcium and hydrogen ions. Brain Res. 208:363–377.
Kvamme, E., Svenneby, G., Hertz, L., andSchousboe, A. 1982. Properties of phosphate activated glutaminase in astrocytes cultured from mouse brain. Neurochem. Res. 7:761–770.
Kvamme, E., andOlsen, B. E. 1981. Evidence for compartmentation of synaptosomal phosphate-activated glutaminase. J. Neurochem. 36:1916–1923.
Whittaker, V. P., andBarker, L. A. 1972. The subcellular fractionation of brain tissue with special reference to the preparation of synaptosomes and their component organelles. Pages 1–52,in Rainer, F. (ed.), Methods of Neurochemistry, Vol. 2. Marcel Dekker, New York.
Booth, R. F., andClark, J. B. 1978. A rapid method for the preparation of relatively pure metabolically competent synaptosomes from rat brain. Biochem. J. 176:365–370.
Hargittai, P., Ágoston, D., andNagy, Á. 1982. Comparative biochemical and biophysical studies on rat brain synaptosomes. FEBS Lett. 137:67–70.
Laj, J. C. K., andClark, J. B. 1979. Preparation of synaptic and nonsynaptic mitochondria from mammalian brain. Pages 51–60,in Colowick, S. P., andKaplan, N. O. (eds.) Methods in Enzymology, Vol. 55. Academic Press, New York, London.
Kvamme, E., andOlsen, B. E. 1980. Substrate mediated regulation of phosphate-activated glutaminase in nervous tissue. Brain Res. 181:228–233.
Zamenhof, S. 1957. Preparation and assay of desoxyribonucleic acid from animal tissue. Pages 696–704,in Colowick, S. P., andKaplan, N. O. (eds.) Methods in Enzymology, Vol. 3. Academic Press, New York, London.
Svenneby, G. 1970. Pig brain glutaminase. Purification and identification of different enzyme forms. J. Neurochem. 17:1591–1599.
Mitchell, P. 1967. Proton-translocation phosphorylation in mitochondria, chloroplasts and bacteria: natural fuel cells and solar cells. Fed. Proc. 26:1370–1379.
Klee, C. B., Crouch, T. H., andRichman, P. G. 1980. Calmodulin. Ann. Rev. Biochem. 49:489–513.
Kvamme, E., andTorgner, I.Aa. 1974. Phosphate-dependent effects of palmitoyl-CoA and stearyl-CoA on phosphate-activated pig brain and pig kidney glutaminase. FEBS Lett. 47:244–247.
Kvamme, E., Tveit, B., andSvenneby, G. 1970. Glutaminase from pig renal cortex. I. Purification and general properties. J. Biol. Chem. 245:1871–1877.
Kvamme, E., andTorgner, I.Aa. 1975. Regulatory effects of fatty acyl-Coenzyme A derivatives on phosphate-activated pig brain and kidney glutaminase in vitro. Biochem. J. 149:83–91.
Fiskum, G., andLehninger, A. L. 1980. The mechanisms and regulation of mitochondrial Ca2+ transport. Fed. Proc. 39:2432–2436.
Meijer, A. J., Groot, G. S. P., andTager, J. M. 1970. Effect of sulphydryl-blocking reagents on mitochondrial anion-exchange reactions involving phosphate. FEBS Lett. 8:41–44.
Strosznajder, J., Tang, W., Manning, R., Lin, A. Y-T., MacQuarrie, R., andSun, G. Y. 1981. Metabolism of oleoyl-CoA in rat brain synaptosomes: Effects of calcium and post-decapitative ischemia. Neurochem. Res. 6:1231–1240.
Pfeiffer, D. R., Schmid, P. C., Beatrice, M. C., andSchmid, H. H. O. 1979. Intramitochondrial phospholipase activity and the effects of Ca2+ plus N-ethylmaleimide on mitochondrial function. J. Biol. Chem. 254:11485–11494.
Benjamin, A. M., andQuastel, J. H. 1974. Fate ofl-glutamate in the brain. J. Neurochem. 23:457–464.
Yu, A. C., Schousboe, A., andHertz, L. 1982. Metabolic fate of14C-labeled glutamate in astrocytes in primary cultures. J. Neurochem. 39:954–960.
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This issue is dedicated to Donald B. Tower.
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Kvamme, E., Svenneby, G. & Torgner, I.A. Calcium stimulation of glutamine hydrolysis in synaptosomes from rat brain. Neurochem Res 8, 25–38 (1983). https://doi.org/10.1007/BF00965651
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DOI: https://doi.org/10.1007/BF00965651