Purification and characterization of developmentally regulated AMP deaminase from Dictyostelium discoideum

Malliaros, David P.; Kozwich, Diane L.; Jahngen, Edwin

doi:10.1111/j.1432-0436.1991.tb00876.x

Cited by 3 publications

(1 citation statement)

References 34 publications

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“…In comparison with aerobic cells, phosphocreatine is reduced, NADH levels are increased, and phosphate and glycolytic intermediates are elevated in anoxic myocytes maintaining ATP stores through glycolysis. It is not known which products or intermediates of glycolysis inhibit AMP deami- nase in situ, although inorganic phosphate and a variety of phosphate compounds alter the kinetics of the purified enzyme in vitro (4,23).…”

Section: Discussionmentioning

confidence: 99%

AMP deaminase in piglet cardiac myocytes: effect on nucleotide metabolism during ischemia

Hohl

1999

American Journal of Physiology-Heart and Circulatory Physiology

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The purpose of this study was to examine in situ regulation of AMP deaminase in newborn piglet cardiac myocytes and to determine its role in nucleotide metabolism during ischemia. When a rapid deenergization paradigm was used to assay AMP deaminase, enzyme activity depended on the hormonal and metabolic status of cells just before deenergization. Inosine 5′-monophosphate (IMP) formation was increased 150% in deenergized myocytes pretreated with phorbol 12-myristate 13-acetate (PMA; EC50 = 4.7 × 10−8 M). This effect was 90% blocked with the protein kinase C (PKC) inhibitor staurosporine. In addition, the β-adrenergic agonist isoproterenol stimulated AMP deaminase activity (EC50 = 1.5 × 10−8M), and IMP formation was directly correlated to intracellular cAMP levels ( r 2 = 0.9). Furthermore, adenosine increased IMP formation, whereas nonrespiring, glycolyzing piglet myocytes had reduced AMP deaminase activity. Pretreatment of perfused piglet hearts with adenosine, but not PMA, before exposure to global ischemia resulted in enhanced conversion of AMP to IMP during the ischemic period. Similar results were obtained in piglet myocytes preincubated with adenosine or PMA before exposure to simulated ischemia. These results may be relevant to the preconditioning phenomenon.

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Section: Discussionmentioning

confidence: 99%

AMP deaminase in piglet cardiac myocytes: effect on nucleotide metabolism during ischemia

Hohl

1999

American Journal of Physiology-Heart and Circulatory Physiology

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Altered Cell-Type Proportioning in Dictyostelium Lacking Adenosine Monophosphate Deaminase

Chae

Fuller

Loomis

2002

Developmental Biology

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The proportions of prespore and prestalk cells in Dictyostelium discoideum are regulated so that they are size invariant and can adjust when the ratio is perturbed. We have found that disruption of the gene amdA that encodes AMP deaminase results in a significantly increased proportion of prestalk cells. Strains lacking AMP deaminase form short, thick stalks and glassy sori with less than 5% the normal number of spores. The levels of prestalk-specific mRNAs in amdA(-) cells are more than twice as high as those in wild-type strains and prespore-specific mRNAs are reduced. Using an ecmA::lacZ construct to mark prestalk cells, we found that amdA(-) null slugs have twice the normal number of prestalk cells. The number of cells expressing an ecmO::lacZ construct was not affected by loss of AmdA, indicating that the mutation results in an increase in PST-A prestalk cells rather than PST-O cells. This alteration in cell-type proportioning is a cell-autonomous consequence of the loss of AMP deaminase since mutant cells developed together with wild-type cells still produced excess prestalk cells and wild-type cells carrying the ecmA::lacZ construct formed normal numbers of prestalk cells when developed together with an equal number of amdA(-) mutant cells.

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Adenosine stimulation of AMP deaminase activity in adult rat cardiac myocytes

Altschuld

Hohl

1993

American Journal of Physiology-Cell Physiology

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Using an in situ assay for analyzing AMP deaminase activity in isolated adult rat ventricular myocytes, we have shown that IMP production is stimulated approximately twofold in cardiac cells incubated with 10 microM adenosine. This effect of adenosine was not blocked by the adenosine A1-receptor antagonist 8-cyclophenyl-1,3-dipropylaxanthine (0.01-1 microM) except at a concentration (100 microM) that may inhibit adenosine transport. Similarly, in situ AMP deaminase activity was not enhanced by treatment with the specific adenosine A1-receptor agonists N6-phenylisopropyl adenosine or cyclopentyladenosine, nor was it sensitive to prior treatment of cells with pertussis toxin. The nucleoside transport blockers S-4-nitrobenzyl-6-thioinosine, dipyridamole, and papaverine inhibited adenosine-induced increases in IMP production by 75-85%, suggesting an intracellular site of action. Modulation of enzyme activity via the transmethylation pathway could not be implicated since incubation of cardiac cells under conditions known to elevate intracellular S-adenosyl-L-homocysteine had no demonstrable effect on AMP deaminase. Furthermore, a direct allosteric effect of adenosine on the partially purified rat cardiac enzyme was not observed. The results indicate that intracellular adenosine modulates rat cardiac AMP deaminase by an unknown mechanism.

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Purification and characterization of developmentally regulated AMP deaminase from Dictyostelium discoideum

Cited by 3 publications

References 34 publications

AMP deaminase in piglet cardiac myocytes: effect on nucleotide metabolism during ischemia

AMP deaminase in piglet cardiac myocytes: effect on nucleotide metabolism during ischemia

Altered Cell-Type Proportioning in Dictyostelium Lacking Adenosine Monophosphate Deaminase

Adenosine stimulation of AMP deaminase activity in adult rat cardiac myocytes

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