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)

Isopycnic equilibration and sedimentation rate studies of rat liver microsomes led previously to the assignment of microsomal constituents into group a1 (monoamine oxidase), group a2 (5'-nucleotidase, alkaline phosphodiesterase I, alkaline phosphatase and cholesterol), group a3 (galactosyltransferase), group b (NADH cytochrome c reductase, NADPH cytochrome c reductase, aminopyrine demethylase, cytochrome b(5) and P 450), and group c (glucose 6-phosphatase, esterase, nucleoside diphosphatase, beta-glucuronidase and glucuronyltransferase). Confirmation and extension of the assignment into groups has been obtained by studying the differential effect of the reagents digitonin, EDTA, and PPi. Digitonin specifically affected the equilibrium density only of the group a2 and (to a lesser extent) group a3, and not of groups b and c under conditions which preserved the structure-linked latency of nucleoside diphosphatase and galactosyltransferase. Within experimental error the rate of sedimentation of all microsomal constituents was unaffected. The morphological appearance under the electron microscope was indistinguishable from that of nondigitonin-treated microsomes, except that a few smooth membranes (< 10%) exhibited broken-looking profiles. Treatment of microsomes with EDTA or PPi detached a substantial part of RNA and released protein in excess over the amount accountable for by detachment of ribosome constituents. This detachment was confirmed by electron microscopy. EDTA and PPi decreased markedly the equilibrium density and the density dispersion of groups b and c, due mainly to the uncoating of rough elements. EDTA and PPi shifted slightly the distribution profiles of groups a towards lower densities, possibly as a result of the release of adsorbed proteins. The combination of EDTA and digitonin, used subsequently, rendered the average equilibrium density of group a2 higher than that of groups b and c. Dense subfractions were thus enriched in constituents of group a2 and showed mainly broken-looking vesicles under the electron microscope. The import of our results on the biochemical and enzymic properties of the subcellular components of the microsome fractions is discussed.
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PMID:Analytical study of microsomes and isolated subcellular membranes from rat liver. IV. Biochemical, physical, and morphological modifications of microsomal components induced by digitonin, EDTA, and pyrophosphate. 436 10

The nature of the compartmentalization of catalase in human myeloid cells is an unresolved issue. Using a rabbit polyclonal antibody specific for catalase, indirect immunocytofluorescence of immature leukemic promyelocytes (HL-60 cells) showed a pattern of small, sharp, punctate staining in the cytoplasm of all cells, while mature neutrophils showed a larger diffuse, flocculent pattern of cytoplasmic staining. Differential centrifugation of nitrogen cavitates of HL-60 cells indicated that the putative catalase-containing compartment was relatively fragile compared with the compartment(s) that contained myeloperoxidase (MPO), beta-hexosaminidase, beta-glucuronidase, and lysosomal alpha-mannosidase activities. Parallel studies using dimethylsulfoxide (DMSO)-induced HL-60 cells and mature neutrophils showed that, in the course of differentiation, there was an apparent shift in the localization of catalase from the granule fraction to the cytosolic fraction. Percoll-sucrose density gradient centrifugation of HL-60 cell cavitates showed a catalase-containing compartment with a mean peak density (1.05 g/mL) significantly lower than that of the major myeloperoxidase-containing compartment (1.08 g/mL); in mature neutrophils, catalase activity comigrated with lactate dehydrogenase (LDH) activity. Catalase in isolated fractions was protected from proteolysis in the absence, but not in the presence, of 0.1% Triton X-100. Digitonin titration experiments confirmed the compartmentalized nature of catalase in immature HL-60 cells and were consistent with a cytosolic localization in mature neutrophils. Ultrastructural localization of catalase by Protein A-gold immunocytochemistry demonstrated four to six catalase-containing compartments in all HL-60 cell profiles. In mature neutrophils, catalase was localized primarily in the cytoplasmic matrix, although in fewer than 2% of the cell profiles, one to two catalase-containing compartments were observed. The changes in catalase localization that occur during myeloid differentiation appear to be similar to the changes that occur during erythroid and megakaryocytic differentiation, and may have potential clinical significance in the classification of acute leukemia and in the development of drug resistance.
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PMID:Changes in the localization of catalase during differentiation of neutrophilic granulocytes. 816 45