Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P20020 (adenosine triphosphatase)
 3,299 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. For a period of 31 days male rats were given a liquid diet containing 36% of its energy as ethanol. Liver mitochondria from these animals demonstrated lowered respiratory control with succinate as substrate, a diminished energy-linked anilinonaphthalene-sulphonic acid fluorescence response, and lowered endogenous ATP concentrations. The phospholipid/protein ratio in mitochondria from these animals was unchanged; only minor alterations in the phospholipid fatty acid composition were observed. 2. In experiments where mitochondria were incubated at 18 degrees C in iso-osmotic sucrose (aging experiments), the above energy-linked properties were lost at an earlier time in organelles from ethanol-fed animals. Phospholipase A2 acitivty was depressed in mitochondria from control animals until respiratory control was lost and ATP was depleted. In contrast, no lag in the expression of phospholipase activity was observed in mitochondria from ethanol-fed rats. This loss of control of the phospholipase resulted in an earlier degradation of membrane phospholipids under the conditions of the aging experiments. 3. The ATPase (adenosine triphosphatase) activities, measured in freshly prepared tightly coupled mitochondria and in organelles uncoupled with carbonyl cyanide p-trifluoromethoxyphenylhydrazone, were not significantly different in ethanol-fed and liquid-diet control animals. When the mitochondria were aged at 18 degrees C, the activity increased with time of incubation in organelles from both groups of animals. A lag was observed, however, as the ATPase activity increased in control preparations. This lag was not present as APTase activity increased in mitochondria from ethanol-fed animals. 4. The significantly lowered values observed for energy-linked functions with succinate as an energy source demonstrate that ethanol elicits an alteration in liver mitochondria that affects the site II-site III regions of the oxidative-phosphorylation system. The apparent lack of control of the phospholipase A2 and ATPase activities in mitochondria from ethanol-fed animals suggests that the membrane microenvironment of these enzymes has been altered such that they can exert their catabolic effects more readily under conditions of mild perturbation. The fatty acid analyses demonstrate that the observed alterations both in the energy-linked functions and in control of the phospholipase and ATPase are not mediated through changes in the acyl chain composition of bulk-phase phospholipids.
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PMID:Effect of chronic ethanol administration on energy metabolism and phospholipase A2 activity in rat liver. 15 52

Phospholipase A2 (PLA2) treatment has been shown previously to stimulate the sodium-dependent high-affinity choline uptake system as assessed by both the specific binding of [3H]hemicholinium-3 ([ 3H]HCh-3) and the uptake of [3H]choline. In the present study, the specificity of PLA2-induced stimulation upon [3H]HCh-3 binding has been examined. PLA2, as well as phospholipase C (PLC), treatment of synaptic membranes produced a dose-dependent increase in the specific binding of [3H]HCh-3 whereas neither phospholipase B nor phospholipase D had any effect. PLC-induced stimulation of [3H]HCh-3 binding resulted from a significant decrease in the Kd without a change in the maximum binding of [3H]HCh-3 binding. PLC treatment of synaptosomes resulted in an inhibition of [3H]choline uptake accompanied by an inhibition of Na+, K+-adenosine triphosphatase activity. In contrast to the increase of [3H]HCh-3 binding, the specific binding of both [3H]desipramine and [3H]mazindol was decreased by PLA2 treatment. After PLA2 treatment, [3H]HCh-3 binding was increased about 2.5-fold over basal levels in different regions of the brain. Electrolytic lesions of the medial septal nucleus and kainic acid-induced lesions of the striatum resulted in a marked reduction of [3H]HCh-3 binding in the hippocampus and the striatum, respectively. Residual [3H]HCh-3 binding in the denervated hippocampus and lesioned striatum was increased by PLA2 treatment but remained lower than that in PLA2-treated controls. Finally, atropine-induced up-regulation of [3H]HCh-3 binding in vivo was not additive with PLA2-induced stimulation. These results support the hypothesis that PLA2 might be involved in the regulation of the sodium-dependent high-affinity choline uptake.
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PMID:Specificity of the activation of [3H]hemicholinium-3 binding by phospholipase A2. 273 47