Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.6.1 (sulfatase)
 3,205 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We and others recently have demonstrated adenosine triphosphate-dependent acidification in a variety of prelysosomal organelles isolated from liver including clathrin-coated vesicles, multivesicular bodies, and Golgi. Little is known, however, regarding the number or distribution of acidic compartments in intact hepatocytes. We therefore have utilized acridine orange, a fluorescent weak base, to study the number and distribution of acidic vesicles of rat hepatocytes in primary culture and compared these with the number and distribution of lysosomes and other storage vesicles. Hepatocytes were found to contain about 170 acidic compartments per cell by fluorescence microscopy. These vesicles were diffusely distributed throughout the cell cytoplasm, with about 50% in the perinuclear area by modified morphometry. The acridine orange staining of these vesicles was reversibly dissipated by monensin, NH4Cl, chloroquine, and primaquine, indicating these vesicles exhibit an acidic interior established by active proton transport. In addition, the cholestatic agent chlorpromazine reversibly inhibited, in a dose-dependent fashion, the redevelopment of a pH gradient in the acidic vesicles after dissipation by monensin. The number and distribution of these acidic vesicles were not significantly different from the number and distribution of vesicles involved in the storage (up to 6 h after internalization) of the fluid phase marker fluorescein-dextran. By contrast, histochemically identifiable lysosomes were fewer in number and significantly more restricted in their distribution to the perinuclear area (89%) than either dextran-storing or acidic vesicles. Electron microscopic studies confirmed that endocytosed dextran as well as another fluid phase marker, colloidal gold, were found predominantly in acid phosphatase- and arylsulfatase-negative vesicles for up to 6 h after internalization. These studies indicate that hepatocytes contain numerous intracellular vesicles acidified by an active H+ transport mechanism. Based on their comparative number and distribution, acidic vesicles probably include vesicles involved in fluid-phase endocytosis but only a minority are lysosomes. The findings also indicate that fluid-phase markers are stored predominantly in vesicles other than histochemically identifiable lysosomes for up to 6 h after internalization. Finally, this technique also affords the opportunity for studying the movement of such vesicles in a vital preparation.
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PMID:Acidic vesicles in cultured rat hepatocytes. Identification and characterization of their relationship to lysosomes and other storage vesicles. 243 4

The existence of lysosomes and acid hydrolase activity was demonstrated in an in vitro blood-brain barrier (BBB) model comprising primary cultures of bovine brain microvessel endothelial cell (BMEC) monolayers. BMEC lysosomes were observed by the uptake of acridine orange and fluorophore-labeled acetylated low-density lipoprotein by fluorescence microscopy. Cytochemical localization of the acid hydrolase, sulfatase, and acid phosphatase (AcP) activities with light microscopy also revealed hydrolase-positive vacuoles or lysosomes that varied in number from cell to cell. BMEC monolayers were fractionated and biochemical assays of the sulfatase, AcP, and beta-galactosidase were performed. Significant activities of the acid hydrolases were found to be associated with lysosome and microsome fractions (69-77%). The majority of beta-galactosidase (approximately 48%) and total sulfatase (approximately 58%) activity was associated with the lysosome fraction of the BMECs. In contrast, approximately 52% of AcP activity was associated with the microsome fraction of the cells. The results of this study are consistent with the demonstration in vivo of acid hydrolases as potential factors in the endocytic pathway for transport of proteins through the BBB and as contributors to the BBB's enzymatic barrier function.
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PMID:Demonstration of acid hydrolase activity in primary cultures of bovine brain microvessel endothelium. 249 11

Fibroblasts from I-cell disease, a genetically-determined lysosomal storage disease, are shown to contain large amounts of phase-dense lysosomes. These lysosomes accumulated acridine orange and were specifically labeled with antibodies to arylsulfatase A. In normal skin fibroblasts the number of arylsulfatase-containing lysosomes was considerably lower. By immunocytochemistry, metabolic labeling and enzyme assay, the arylsulfatase A in I-cell fibroblasts was shown to be synthesized, stored and secreted at a level that was several-fold higher than that present in heterozygous I-cell or normal fibroblasts. Arylsulfatase A in I-cell fibroblasts differed from arylsulfatase in normal fibroblasts by the absence of endoglycosidase H-sensitive phosphorylated oligosaccharides. These findings indicate that arylsulfatase A in I-cells is targeted to lysosomes by a mechanism that does not appear to involve the phosphorylated mannose marker.
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PMID:Targeting of phosphomannosyl-deficient arylsulfatase A to lysosomes of I-cell fibroblasts. 289 90