Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:3.2.1.31 (beta-glucuronidase)
7,680 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The lysosomal compartment has been examined in activated T-lymphocytes by immunogold electron microscopy and subcellular fractionation. Immunoprecipitation and sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) of radiolabelled extracts of the T-cells showed that they contained three antigens which are fundamental to normal lysosomal function: a representative lysosomal enzyme beta-glucuronidase, a lysosomal associated membrane protein (LAMP-1), and the cation-independent mannose 6-phosphate lysosomal enzyme targeting receptor (MPR). Immunogold labelling showed that beta-glucuronidase was present in the rough endoplasmic reticulum, the Golgi complex and Golgi-associated vesicles. The enzyme was also found to accumulate in distinct, non-Golgi organelles in which LAMP-1 was co-localized, probably lysosomes. LAMP-1 was also found in tubular elements of the Golgi and in a complex of vesicles clustered near the nucleus where MPR was also present at high density. Fractionation of homogenates from lymphocytes on Percoll gradients revealed that beta-glucuronidase was distributed throughout the low density region containing rough endoplasmic reticulum, Golgi and plasma membrane components, and the high density region which contained only lysosomal activity. Multiple immunogold electron microscopy of the latter fraction showed the presence of homogenous vesicles which had large amounts of beta-glucuronidase within the lumen, LAMP-1 at the periphery and no MPR. These vesicles were probably mature lysosomes, arising from pre-lysosomal organelles enriched for LAMP-1 and MPR.
...
PMID:Localization of lysosomal antigens in activated T-lymphocytes. 174 96

In this study we have examined the mechanism underlying the contact-mediated transfer of a lysosomal enzyme from lymphocytes to fibroblasts in culture. We found that although antibody against the mannose 6-phosphate lysosomal targetting receptor (MPR) completely inhibited fibroblast uptake of the lysosomal enzyme beta-glucuronidase (Gus) from the culture medium, it had no effect on the transfer of the enzyme from normal lymphocytes. In contrast, the presence of antibody that prevented the adhesion of the lymphocytes to the fibroblasts inhibited Gus acquisition but had no effect on endocytosis. Immunogold electron microscopy of the contact site between the two types of cell showed that the transfer of Gus involved uncoated vesicles localized near the cell surface of the fibroblast at sites of contact with the lymphocytes. The acquired lymphocyte enzyme was shown to be transported to the fibroblast lysosomes.
...
PMID:Contact-dependent transfer of a lysosomal enzyme from lymphocytes to fibroblasts. 180 98

The purification of rat liver beta-glucuronidase from a lysosomal fraction by methods including affinity chromatography, chromatofocusing and preparative PAGE steps is described. Molecular weights of 300,000 and 150,000 were estimated by two dimensional gradient PAGE/immunoelectrophoresis of the lysosomal extract. Isoelectrofocusing in agarose gel followed by immunoelectrophoresis in the second dimension revealed the presence of at least five maxima in the range pH 4.3-7.4. The structural assessment of the carbohydrate chains of lysosomal and microsomal beta-glucuronidase was performed by lectin affinity immunoelectrophoresis. Reaction with Concanavalin A indicated the presence of bi-antennary complex, oligomannosidic and hybrid type structures, whereas the absence of tri- and tetra-antennary complex type structures was deduced from the lack of interaction with phytohemagglutinin-L. The reaction with Lens culinaris agglutinin, Pisum sativum agglutinin and Lotus tetragonolobus lectin revealed that part of the glycans contained a fucose alpha(1-6)-linked to the N-acetylglucosamine attached to asparagine. The presence of terminal beta(1-4)-galactose residues was detected with Ricinus communis agglutinin I.
...
PMID:Purification of beta-glucuronidase and structural assessment of the carbohydrate chains by lectin affinity immunoelectrophoresis. 184 76

Mouse L cells that possess the cation-independent mannose 6-phosphate (Man 6-P)/insulin-like growth factor (IGF) II receptor change the extent to which they dephosphorylate endocytosed acid hydrolases in response to serum (Einstein, R., and C. A. Gabel. 1989. J. Cell Biol. 109:1037-1046). To investigate the mechanism by which dephosphorylation competence is regulated, the dephosphorylation of individual acid hydrolases was studied in Man 6-P/IGF II receptor-positive and -deficient cell lines. 125I-labeled Man 6-P-containing acid hydrolases were proteolytically processed but remained phosphorylated when endocytosed by receptor-positive L cells maintained in the absence of serum; after the addition of serum, however, the cell-associated hydrolases were dephosphorylated. Individual hydrolases were dephosphorylated at distinct rates and to different extents. In contrast, the same hydrolases were dephosphorylated equally and completely after entry into Man 6-P/IGF II receptor-positive Chinese hamster ovary (CHO) cells. The dephosphorylation competence of Man 6-P/IGF II receptor-deficient mouse J774 cells was more limited. beta-Glucuronidase produced by these cells underwent a limited dephosphorylation in transit to lysosomes such that diphosphorylated oligosaccharides were converted to monophosphorylated species. The overall quantity of phosphorylated oligosaccharides associated with the enzyme, however, did not decrease within the lysosomal compartment. Likewise, beta-glucuronidase was not dephosphorylated when introduced into J774 cells via Fc receptor-mediated endocytosis. The CHO and J774 cell lysosomes, therefore, display opposite extremes with respect to their capacity to dephosphorylate acid hydrolases; within CHO cell lysosomes acid hydrolases are rapidly and efficiently dephosphorylated, but within J774 cell lysosomes the same acid hydrolases remain phosphorylated. This difference in processing indicates that lysosomes themselves exist in a dephosphorylation-competent and -incompetent state. Man 6-P-bearing acid hydrolases endocytosed by the L+ cells in the absence of serum were not distributed uniformly throughout the lysosomal compartment. The change in the dephosphorylation competence of L cells in response to serum suggests, therefore, that these cells contain multiple populations of lysosomes that differ with respect to their content of a mannose 6-phosphatase, and that serum factors affect the distribution of hydrolases between the different compartments.
...
PMID:Cell- and ligand-specific dephosphorylation of acid hydrolases: evidence that the mannose 6-phosphatase is controlled by compartmentalization. 184 1

Macrophages express a mannose-specific endocytosis receptor that binds and internalizes mannose-terminated glycoproteins. Infection of mouse peritoneal macrophages with Leishmania donovani resulted in a decrease in mannose-receptor activity. With 125I-labelled beta-glucuronidase as ligand, a 2-fold decrease in uptake rate was observed in infected cells, with no change in Kuptake. Cell-surface binding of 125I-mannose-BSA was diminished 2.5-fold after infection. The decrease in ligand binding appeared to be due to a decrease in the number of sites, with no change in affinity. Elimination of parasites from infected cells by treatment with neoglycoprotein-conjugated methotrexate resulted in an increase in receptor number. Cycloheximide suppressed the drug-treatment-mediated rise in receptor number in infected macrophages. A decrease in receptor activity was also observed in liver Kupffer cells isolated from parasite-infected mice. Binding of ligand by another carbohydrate receptor, the mannose 6-phosphate receptor, was not altered by infection. Phagocytosis of yeast cells was also not altered. These results suggest that mannose receptor synthesis in macrophages is specifically suppressed after infection with Leishmania parasites.
...
PMID:Down-regulation of mannose receptors on macrophages after infection with Leishmania donovani. 185 73

RIF-1 mouse tumors express high levels of beta-glucuronidase activity relative to most normal tissues. The high activity can be exploited for targeting specific drugs preferentially to tumor tissues. In this study we examined the kinetics of 8-hydroxyquinoline (8-OHQ) accumulation in tumor and in several normal tissues resulting from the in vivo deconjugation of 8-hydroxyquinolyl-glucuronide (8-OHQ-GlcA). Tumors were acidified with D-glucose and NaHCO3 prior to the administration of 8-OHQ-GlcA; subsequently the deconjugated aglycone, 8-OHQ, accumulated preferentially in tumors and reached peak levels between 30 and 60 min after the 8-OHQ-GlcA injection. Mild hyperthermia of 30 min at 43 degrees C to the tumors further increased their peak 8-OHQ levels by a factor of 2-3. Some normal tissues, mostly kidney, liver, and colon, also accumulated 8-OHQ, but the aglycone appeared early in the normal tissues (near 30 min post-injection) and was significantly reduced by 60 min when 8-OHQ remained high in the tumor. Administration of 8-OHQ-GlcA alone, without prior tumor acidification, failed to produce measurable accumulations of 8-OHQ in tumors and in normal tissues. Tissue clearance of 8-OHQ is mediated primarily by the enzymatic reconjugation of 8-OHQ via UDP-glucuronosyltransferase (UDPGT). UDPGT activity was high in liver, kidney, and bowel, but low in the RIF tumor, spleen, muscle, and brain. Hyperthermia had only a modest effects on UDPGT activity: a heat dose of 30 min at 45 degrees C reduced activity less than 60%. Thus, preferential accumulation and prolonged retention of 8-OHQ in RIF tumors may be caused by a combination of factors: a) high tumor beta-glucuronidase activity, b) selective tumor acidification during hyperglycemia, c) low tumor UDPGT activity, and d) other factors, such as tumor blood flow.
...
PMID:Tumor-targeted delivery of 8-hydroxyquinoline. 190 10

Adherent cultures of rat peritoneal macrophages secrete lysozyme and the lysosomal marker enzymes beta-glucuronidase, beta-N-acetylglucosaminidase and acid phosphatase; the levels of secreted lysosomal cathepsin D, however, were found to be insignificant. Incubation of the cells at 4 degrees C for 15 min with yeast mannan or with 50 mM mannose, methyl alpha-glucopyranoside, or N-acetylglucosamine caused the concentration of cathepsin D in the culture medium to increase 30-40-fold; mannose-6-phosphate had no effect. 125I-labeled cathepsin D was prepared and the binding constant to the macrophage cell surface was determined to be KD = 27 nM. The data suggest that cathepsin D binds to the mannose receptor of macrophages and that binding to this receptor is not in equilibrium with the bulk medium.
...
PMID:Binding of cathepsin D to the mannose receptor on rat peritoneal macrophages. 193 26

This investigation studied the effects of a shift from a mixed diet to a lactovegetarian diet on some cancer-associated bacterial enzymes in human feces (beta-glucuronidase, beta-glucosidase, and sulphatase). Three months after the shift to the lactovegetarian diet, there was a significant decrease in beta-glucuronidase, beta-glucosidase, and sulphatase activities per gram feces wet weight (p less than 0.05, less than 0.05, and less than 0.001, respectively). In contrast, glucuronide and glucoside hydrolysis remained unchanged per gram dry weight, although sulphatase activity was still significantly lowered when expressed this way (p less than 0.01). However, the fecal excretion increased significantly (p less than 0.05). Part of the explanation for the decreased enzyme activities is obviously a dilution effect, because much of the increased fecal weight after the shift in diet was associated with a higher water content. The higher water content was probably due to a higher fiber intake (p less than 0.001). Thus, the results in this paper indicate that a change from a mixed diet to a lactovegetarian diet leads to a decrease in certain enzyme activities proposed to be risk factors for colon cancer.
...
PMID:Shift from a mixed diet to a lactovegetarian diet: influence on some cancer-associated intestinal bacterial enzyme activities. 212 19

Cathepsin L, a lysosomal cysteine protease, is the major excreted protein of transformed mouse NIH 3T3 cells. Previous studies have shown that asparagine-linked oligosaccharides associated with the secreted hydrolase contain mannose 6-phosphate (Man 6-P), the recognition marker for transport of newly synthesized acid hydrolases to lysosomes. To investigate the mechanism by which cathepsin L evades targeting to lysosomes, we determined the structure of the enzyme's oligosaccharides and analyzed its interaction with the cation-independent mannose 6-phosphate (Man 6-PCl) receptor. Oligosaccharides associated with procathepsin L isolated from the medium of [3H]mannose-labeled J774 cells were remarkably homogeneous; all of the radiolabeled structures were high mannose-type units that contained two phosphomonoesters and 7 mannose residues. Both the alpha 1,3- and alpha 1,6-branches of the oligosaccharides were phosphorylated. Oligosaccharides released by endoglycosidase H from [3H]mannose-labeled procathepsin L bound to a Man 6-PCl receptor affinity column. Despite the high affinity binding of these oligosaccharides, the intact glycoprotein was not a good ligand for the Man 6-PCl receptor. Procathepsin L was internalized poorly by Man 6-P receptor-mediated endocytosis and the purified acid protease interacted weakly with a Man 6-PCl affinity column. In contrast, pro-beta-glucuronidase (another acid hydrolase produced by J774 cells) was an excellent ligand for the Man 6-PCl receptor as judged by the endocytosis and affinity chromatographic assays. Phosphorylated oligosaccharides associated with the J774-secreted pro-beta-glucuronidase were heterogeneous and contained both mono- and diphosphorylated species. Tryptic glycopeptides generated from [3H]mannose-labeled procathepsin L, unlike the intact protein, were excellent ligands for the Man 6-PCl receptor. The results indicate that oligosaccharides associated with procathepsin L are processed uniformly to diphosphorylated species that bind with high affinity to the Man 6-PCl receptor. Protein determinants inherent within the intact acid hydrolase, however, inhibit the high affinity binding of these oligosaccharides and, as a result, impair the interaction of procathepsin L with the receptor.
...
PMID:Protein determinants impair recognition of procathepsin L phosphorylated oligosaccharides by the cation-independent mannose 6-phosphate receptor. 216 20

BALB/3T3 fibroblasts (3T3) were observed to secrete latent, pepsin-activatable forms of cathepsin B and cathepsin L as well as an active form of beta-glucuronidase when cultured in the absence of serum. The secretion of these proteins was stimulated by the cation ionophore monensin: cathepsin B, 4.3-fold; cathepsin L, 7.2-fold; and beta-glucuronidase, 3.1-fold. These increases were accompanied by a 50% decline in cellular levels of the active forms of these enzymes and by the cellular accumulation of latent forms of cathepsin B and cathepsin L. Latent forms of beta-glucuronidase were not detected. In contrast, Moloney murine sarcoma virus-transformed BALB/3T3 fibroblasts (MMSV) secreted greatly increased amounts of latent cathepsin B (17-fold) and latent cathepsin L (27-fold), and moderately increased amounts of active beta-glucuronidase (2-fold) in a manner which was not further increased by monensin. The increased monensin-insensitive secretion of these lysosomal enzymes by MMSV cells may be due to a transformation-induced decrease in mannose 6-phosphate receptors. Thus, 3T3 cells bound the neoglycoconjugate pentamannosyl 6-phosphate-bovine serum albumin at 4 degrees C in a pentamannosyl 6 phosphate and mannose 6-phosphate-inhibitable manner, whereas MMSV cells showed no measurable cell surface mannose 6-phosphate receptor binding activity.
...
PMID:Differences in targeting and secretion of cathepsins B and L by BALB/3T3 fibroblasts and Moloney murine sarcoma virus-transformed BALB/3T3 fibroblasts. 216 39


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---