Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.1.5 (neuropathy target esterase)
 1,070 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Hydrolysis of 2-[1-14C]oleoyl phosphatidylcholine and of 1-[1-14C]oleoyl lysophosphatidylcholine by lysosomes prepared from rat liver using Triton WR-1339 has been studied. At pH 5.0 sodium taurocholate stimulated the release by the soluble lysosomal fraction of labelled lysophosphatidylcholine, diacyl- and monoacylglycerol and fatty acids from [14C]phosphatidylcholine. The time course of appearance of labelled products suggested that monoacylglycerol could be released as a result of the action of phospholipase A1 followed by lysophospholipase C or by the initial action of phospholipase C followed by monoacylglycerol lipase. The hydrolysis of 1-[14C]acyl lysophosphatidylcholine was also stimulated by sodium taurocholate under similar conditions; however, only release of monoacylglycerol was increased, whereas release of fatty acid was inhibited. Mg2+ inhibited the release of labelled monoacylglycerol and of fatty acid from lysophosphatidylcholine. The detergents deoxycholate and Triton X-100 and phospholipids were strongly inhibitory. 5'-AMP almost completely suppressed release of monoacylglycerol but increased release of fatty acid. Chloroquine strongly suppressed release of monoacylglycerol and only at high concentration (1.25 mM) diminished fatty acid release. In the presence of sodium taurocholate the predominant mechanism for degradation of phosphatidylcholine by the soluble fraction of lysosomes involves phospholipase A followed by phospholipase C. Assay of release of monoacylglycerol from [14C]lysophosphatidylcholine catalyzed by extracts of fibroblasts from patients with Niemann-Pick disease and controls in the presence of taurocholate revealed that lysophospholipase C activity was lacking in those cell lines that were deficient in sphingomyelinase. This suggests that lysophospholipase C and sphingomyelinase activities may be catalyzed by one enzyme.
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PMID:Degradation of lysophosphatidylcholine by lysosomes. Stimulation of lysophospholipase C by taurocholate and deficiency in Niemann-Pick fibroblasts. 673 21

The role of the lysosome in the metabolism of lysophosphatidylcholine was investigated in isolated rat hepatocytes. Chloroquine, primaquine, and ammonium chloride caused a 2.5-fold increase in radioactive lysophosphatidylcholine in [methyl-3H]choline-labeled cells. This effect was confirmed by a 1.7-fold increase in lysophosphatidylcholine mass in chloroquine-treated hepatocytes. Chloroquine caused a 2.7-fold increase in radioactive lysophosphatidylethanolamine in [1-3H]ethanolamine-labeled cells and a 2.3-fold increase in radioactive lysophosphatidylcholine in [methyl-3H]methionine-labeled cells. Chloroquine did not affect formation of choline-containing aqueous metabolites or the level of radioactivity in phosphatidylcholine (PC). The effect of chloroquine on radioactive lysophosphatidylcholine accumulation was concentration-dependent and occurred within 10 min, consistent with rapid inhibition of lysosomal function. As there was no observed decrease in the 3H in PC, the accumulation of lysophosphatidylcholine was likely due to the inhibition of acid lysophospholipase activity in chloroquine-treated cells. The accumulation of lysophosphatidylcholine in the presence of chloroquine was observed in both short-term- (30 min) and equilibrium-(24 h) [methyl-3H]choline-labeled cells. Simultaneous incubation of hepatocytes with both albumin and chloroquine increased the radioactivity in lysophosphatidylcholine in the medium independently of the accumulation of radioactive lysophosphatidylcholine in the cells. The results suggest that there are separate pools of lysophosphatidylcholine in the hepatocyte and that the pool donated to an extracellular acceptor is different from the lysosomal pool.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Involvement of the lysosome in the catabolism of intracellular lysophosphatidylcholine and evidence for distinct pools of lysophosphatidylcholine. 826 12