Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.31 (beta-glucuronidase)
 7,680 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

When rat hepatocytes were cultured in the presence of various specific protease inhibitors, lysosomal acid phospholipase A1 activity decreased progressively. Exposure of the cultured cells to 0.1 micrograms/ml of pepstatin, E 64, leupeptin or chymostatin also reduced the catalytic activities of several lysosomal marker enzymes. Irrespective of the protease inhibitor type employed, acid phospholipase A1 activity reacted most sensitively, followed by acid phosphatase, acid beta-N-acetyl-D-hexosaminidase and acid beta-glucuronidase. Of the protease inhibitors studied, pepstatin appeared to be most potent in reducing lysosomal enzyme activities in cultured hepatocytes. These findings suggest that proteolytic processes at as yet unknown, possibly extralysosomal sites play an important role in the turnover rates of lysosomal enzymes.
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PMID:Protease inhibitors reduce lysosomal acid phospholipase A1 activity in cultured rat hepatocytes. 231 14

Lungs were obtained from rabbit fetuses (on each day from d 24 to d 30 of gestation), neonates and adults, and were fractionated for enzyme assays. The developmental profile of cytidylyltransferase shows a decrease in specific activity from d 25 to d 29 (P less than 0.05) then a sharp rise from d 30 to adult values in d 0 neonates (P less than 0.05). Cholinephosphotransferase specific activity changes little from d 25 to birth, apart from a non-significant peak on d 29. There is a sharp rise from neonatal d 0 to adult values on d 1 (P less than 0.01). The specific activity of microsomal phospholipase A2 declines from d 25 to reach adult values in the neonate (P = 0.05). In contrast, the specific activity of lysosomal phospholipase A2 rises from d 24-28 then falls in the neonate (P less than 0.05). Adult values are higher than those in the fetus and neonate. Three other lysosomal enzyme specific activities rise to d 28 then decline: phospholipase A1, beta-galactosidase, and beta-glucuronidase. The results demonstrate that the level of microsomal phospholipase A2 does not control the extent of remodelling of phosphatidylcholine for surfactant production. Lysosomal phospholipase A2 only increases in parallel with the other lysosomal enzymes, indicating an increase in the number of lysosomes in the lung.
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PMID:Developmental changes in enzyme activities in fetal and neonatal rabbit lung. Cytidylyltransferase, cholinephosphotransferase, phospholipases A1 and A2, beta-galactosidase, and beta-glucuronidase. 632 5

Leupeptin is an established, reversible inhibitor of cathepsin B, a lysosomal cysteine proteinase. Yet, in rat fibroblasts as well as in foetal mouse calvaria, we observed an increase of the activity of cathepsin B in homogenates of cells and tissue harvested after culture in the presence of leupeptin. This effect was also seen for other lysosomal hydrolases, namely sphingomyelinase, N-acetyl-beta-glucosaminidase, arylsulphatase A and phospholipase A1 in fibroblasts, and beta-glucuronidase in mouse calvaria. In calvaria, antipain, another reversible cysteine proteinase inhibitor, caused a similar effect, whereas E-64, an irreversible inhibitor, was consistently inhibitory of the cathepsin B activity; yet it also caused an increase of beta-glucuronidase activity. The effect of leupeptin in fibroblasts was dose and time-dependent, required the continuous presence of the inhibitor, and was not dependent from protein synthesis. Actually, addition of cycloheximide caused a severe loss of activity of cathepsin B and of sphingomyelinase. In the presence of both cycloheximide and leupeptin, however, these two activities were retained to a value corresponding to that found in excess in cells cultivated with leupeptin alone. The data therefore suggests that leupeptin exerts the effects described in this paper by preventing the degradation of cathepsin B, sphingomyelinase and probably several other lysosomal hydrolases by cysteine proteinases. We therefore propose that cysteine proteinases play a key role in the control of the steady-state levels of these enzymes in normal conditions.
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PMID:Increased activities of cathepsin B and other lysosomal hydrolases in fibroblasts and bone tissue cultured in the presence of cysteine proteinases inhibitors. 793 17

The Arabidopsis mutant defective in anther dehiscence1 (dad1) shows defects in anther dehiscence, pollen maturation, and flower opening. The defects were rescued by the exogenous application of jasmonic acid (JA) or linolenic acid, which is consistent with the reduced accumulation of JA in the dad1 flower buds. We identified the DAD1 gene by T-DNA tagging, which is characteristic to a putative N-terminal transit peptide and a conserved motif found in lipase active sites. DAD1 protein expressed in Escherichia coli hydrolyzed phospholipids in an sn-1-specific manner, and DAD1-green fluorescent protein fusion protein expressed in leaf epidermal cells localized predominantly in chloroplasts. These results indicate that the DAD1 protein is a chloroplastic phospholipase A1 that catalyzes the initial step of JA biosynthesis. DAD1 promoter::beta-glucuronidase analysis revealed that the expression of DAD1 is restricted in the stamen filaments. A model is presented in which JA synthesized in the filaments regulates the water transport in stamens and petals.
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PMID:The DEFECTIVE IN ANTHER DEHISCIENCE gene encodes a novel phospholipase A1 catalyzing the initial step of jasmonic acid biosynthesis, which synchronizes pollen maturation, anther dehiscence, and flower opening in Arabidopsis. 1159 96