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

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Query: EC:3.1.6.1 (sulfatase)
3,205 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The aim of this work was to establish, on a quantitative basis, the subcellular distribution of the enzyme system that converts arachidonic acid into prostaglandin (PG) E2 in mouse resident peritoneal (MRP) macrophages. Kinetic studies were conducted on cell-free extracts derived from cells cultivated for 1 d, using [1-14C]arachidonic acid as substrate and measuring the label in PGE2 after extraction and thin layer chromatography. The activity was synergistically enhanced by L-adrenaline and reduced glutathione, inhibited by indomethacin, and linearly related to the concentration of the cell-free extract. It was labile at 0 degrees C in the medium used for homogenization and fractionation of the cells (half-life less than 2 h). Addition of catalase (0.15 mg/ml) to the suspension medium increased the initial activity (by congruent to 70%) and the stability (half-life congruent to 6 h) of the enzyme in cytoplasmic extracts. It enabled us to establish the density distribution after isopycnic centrifugation in a linear gradient of sucrose. The sample centrifuged consisted of untreated cytoplasmic extracts, or cytoplasmic extracts treated with digitonin and Na pyrophosphate. Comparison of the centrifugation behavior of PGE2 synthesis activity with that of various enzymes used as reference for the major subcellular entities has revealed that PGE2 synthesis fairly fits the density profile of sulfatase C in each case. The conclusion is that at least the rate-limiting reaction in the conversion of arachidonic acid into PGE2 is catalyzed by an enzyme associated with the endoplasmic reticulum.
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PMID:Subcellular localization of the PGE2 synthesis activity in mouse resident peritoneal macrophages. 642 Apr 97

Macrophages are common in rat testicular interstitial tissues. Interstitial-tissue macrophages were characterized using ultrastructural, cytochemical, immunologic, and autoradiograhic methods. Testicular interstitial-tissue macrophages have a single indented nucleus, paranuclear Golgi complex, rough endoplasmic reticulum, coated vesicles, and numerous heterogeneous lysosomal vacuoles. Long filopodia and lamellopodia extent from the macrophage cell body into the lymphatic space. Macrophages are usually found adjacent to Leydig cells, and numerous Leydig cell processes are inserted into coated membrane invaginations on the macrophage surface. Secondary lysosomal vacuoles in the macrophage are cytochemically reactive for acid phosphatase (trimetaphosphatase) and aryl sulfatase. Testicular interstitial macrophages are endocytically active, avidly incorporating exogenously administered trypan blue dye and monomeric plutonium-citrate. Macrophages were isolated from the testes by allowing them to adhere to glass. The isolated macrophages were found to have receptors for the Fc portion of immunoglobulin G on their surface. The association of macrophages with Leydig cells and their endocytic and immunologic activity suggests that these cells may play an important role(s) in testicular functions. In addition, the ability of these cells to incorporate exogenous materials indicates that they could have a role in gonadal toxicity reactions.
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PMID:Structure, cytochemistry, endocytic activity, and immunoglobulin (Fc) receptors of rat testicular interstitial-tissue macrophages. 668 29

This study has examined the fine structure and some cytochemical characteristics of the endodermal and mesothelial cells of the rhesus monkey yolk sac between 25 and 66 days of gestation. The endodermal cells were characterized by abundant granular endoplasmic reticulum, some agranular endoplasmic reticulum, a well-developed Golgi apparatus, and numerous large mitochondria. During the earlier part of the period studied, endodermal cells had a few acid phosphatase and arylsulfatase-positive lysosomes and moderate numbers of catalase-positive microperoxisomes. During the later stages of development, large granules (believed to be lysosomes) with a heterogeneous content were numerous in the cytoplasm. Mesothelial cells showed fewer development changes. Throughout this period they were usually flattened cells with long microvilli, small mitochondria, and limited amounts of granular endoplasmic reticulum. The mesothelial cells had acid phosphatase reaction product in the Golgi region and occasional large vesicles, but were negative for arylsulfatase and catalase. One specimen was incubated at 37 degrees C in the presence of horseradish peroxidase in order to examine endocytosis. Both the mesothelial cells and endodermal cells internalized the peroxidase into a variety of cytoplasmic vesicles. Based on their cytology, the endodermal cells may function in the synthesis of serum proteins during this period, as has been suggested in other species. They may also be involved in lipid metabolism. The mesothelial cells appeared less synthetically active, but evidence suggested that they may be involved in collagen and extracellular matrix production. The endocytic activity displayed by both cell types may indicate a role in fluid and metabolite transfer across the epithelia. The cytology of both cell types was very similar to that described for human yolk sacs, suggesting that the rhesus monkey may be a useful species in which to study the maturation of yolk sac function.
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PMID:A fine structural and cytochemical study of the rhesus monkey yolk sac: endoderm and mesothelium. 684 66

Basophils and mast cells possess large metachromatically staining granules which contain sulfated glycosaminoglycans as well as vasoactive compounds. To determine whether these granules might also have lysosomal properties, we used electron microscopy and cytochemistry to localize arylsulfatase B in rat basophils and mast cells. In basophils of bone marrow, enzymatic reaction product was consistently seen in many, but not all, of the basophil granules. In some cells, the enzyme could also be demonstrated in the Golgi region, restricted to a single cisterna and small vesicles. It was never seen in rough endoplasmic reticulum (RER), although the paucity of cells made adequate sampling difficult. In mast cells of bone marrow and the peritoneal cavity, enzymatic reaction product was consistently found in some cytoplasmic granules of varying sizes and shapes where it characteristically rimmed the periphery of the granule just beneath the limiting membrane. It should be emphasized, however, that the majority of granules were not reactive. Reaction product could also be found occasionally in segments of RER, and in the Golgi region with a distribution similar to that of the basophil. The presence of lysosomal arylsulfatase in granules of developing basophils in bone marrow suggests that some basophil granules, like those of neutrophils, eosinophils, and monocytes are primary lysosomes. Some mast cell granules also contain this lysosomal enzyme, although it is not clear from the present data whether these granules are primary or secondary lysosomes.
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PMID:Cytochemical localization of arylsulfatase B in rat basophils and mast cells. 741 98

The biosynthesis of acid sphingomyelinase in normal and I-cell disease fibroblasts was investigated by metabolic labeling with [35S]methionine and immunoprecipitation followed by polyacrylamide gel electrophoresis and fluorography. Two major polypeptides with apparent molecular masses of 75 and 72 kDa (peptide chains of 64 and 61 kDa, respectively) and a minor one with molecular mass of 57 kDa (peptide chain of 47 kDa) were found intracellularly soon after pulse labeling. The 75-kDa form is assumed to be the propropolypeptide of sphingomyelinase which is converted into the precursor form of 72 kDa. The precursor is subjected to two distinct processing events. A minor part is already cleaved in the endoplasmic reticulum-Golgi complex yielding the beta-endo-N-acetylglucosaminidase H-resistant form of 57 kDa; whereas, the major part of the precursor is processed within 4 h to a 70-kDa mature beta-endo-N-acetylglucosaminidase H-sensitive form of sphingomyelinase, which is subsequently converted into a polypeptide with molecular mass of 52 kDa within a chase of about 20 h. Both the precursor (72 kDa) as well as its early cleavage product of 57 kDa are secreted into the culture medium to a minor extent. Intracellular transport of sphingomyelinase into lysosomes depends on the phosphomannosyl specific receptor by following criteria: (i) about 80% of newly synthesized precursor was secreted in NH4Cl-treated fibroblasts as well as in I-cells, (ii) the maturation of sphingomyelinase was inhibited in normal fibroblasts exposed to NH4Cl as well as in I-cell fibroblasts, and (iii) the [32P]phosphate associated with oligosaccharides was cleavable by beta-endo-N-acetylglucosaminidase H. However, endocytosis of radiolabeled extracellular precursor by fibroblasts was not prevented by the addition of mannose 6-phosphate, whereas uptake of arylsulfatase A and beta-hexosaminidase was almost completely blocked under these conditions. This indicates that endocytosis of acid sphingomyelinase by cultured fibroblasts might be mediated by an alternative pathway.
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PMID:Processing of human acid sphingomyelinase in normal and I-cell fibroblasts. 810 25

In sulfatases a Calpha-formylglycine residue is found at a position where their cDNA sequences predict a cysteine residue. In multiple sulfatase deficiency, an inherited lysosomal storage disorder, catalytically inactive sulfatases are synthesized which retain the cysteine residue, indicating that the Calpha-formylglycine residue is required for sulfatase activity. Using in vitro translation in the absence or presence of transport competent microsomes we found that newly synthesized sulfatase polypeptides carry a cysteine residue and that the oxidation of its thiol group to an aldehyde is catalyzed in the endoplasmic reticulum. A linear sequence of 16 residues surrounding the Cys-69 in arylsulfatase A is sufficient to direct the oxidation. This novel protein modification occurs after or at a late stage of cotranslational protein translocation into the endoplasmic reticulum when the polypeptide is not yet folded to its native structure.
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PMID:Conversion of cysteine to formylglycine: a protein modification in the endoplasmic reticulum. 934 45

Sulfatases undergo an unusual protein modification leading to conversion of a specific cysteine residue into alpha-formylglycine. This conversion is essential for catalytic activity. In arylsulfatase A the alpha-formylglycine is generated inside the endoplasmic reticulum at a late stage of protein translocation. Using in vitro translation in the presence of transport-competent microsomes we found that arylsulfatase B is also modified in a similar way by the formylglycine-generating machinery. Modification depended on protein transport and on the correct position of the relevant cysteine. Arylsulfatase A and B did not compete for modification, as became apparent in co-expression experiments. This could argue for an association of the modification machinery with the protein translocation apparatus.
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PMID:Conversion of cysteine to formylglycine in eukaryotic sulfatases occurs by a common mechanism in the endoplasmic reticulum. 950 42

Net sulfation of 4-methylumbelliferone in intact hepatocytes is regulated, in part, by substrate cycling between sulfotransferases (SULT) and arylsulfatases (ARS). Thus, ARS have the potential to influence rates of net sulfate conjugation of a variety of compounds in intact cells via interaction with SULT. Unlike ARSA and ARSB, which are lysosomal, steroid sulfate sulfatase (ARSC, also known as STS) is localized exclusively in the endoplasmic reticulum (ER). The present study was designed to assess the existence and extent of substrate cycling between steroids and their sulfate conjugates through ARSC and SULT, and also to initiate studies of the topology of the catalytic site of ARSC in the rat liver ER. Addition of rat liver microsomes to cytosol and 3'-phosphoadenosine 5'-phosphosulfate (PAPS) reduced rates of sulfation of dehydroepiandrosterone (DHEA) by SULT, and similarly hydrolysis of DHEA sulfate (DHEAS) was reduced when recombinant human hydroxysteroid SULT was added to rat liver microsomes in the presence of PAPS. There was no evidence for ARSC latency in the presence of detergent at either 4 or 37 degrees C, indicating that facilitated transport of steroid sulfates across the ER membrane may not be required for ARSC activity. The effect of proteases on ARSC activity in intact and disrupted microsomes was determined and compared with effects on components of the glucose-6-phosphatase system known to be localized on the lumenal and cytoplasmic surfaces of the ER. In contrast to the components of the glucose-6-phosphatase system, activity of ARSC in both intact and disrupted microsomes was substantially more resistant to protease inactivation. Our results indicate that substrate cycling of steroids and their sulfates does occur, and suggest that the active site of ARSC may be located within the ER membrane.
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PMID:Microsomal steroid sulfatase: interactions with cytosolic steroid sulfotransferases. 956 44

In multiple sulfatase deficiency, a rare human lysosomal storage disorder, all known sulfatases are synthesized as catalytically poorly active polypeptides. Analysis of the latter has shown that they lack a protein modification that was detected in all members of the sulfatase family. This novel protein modification generates a 2-amino-3-oxopropanoic acid (C alpha-formylglycine) residue by oxidation of the thiol group of a cysteine that is conserved among all eukaryotic sulfatases. The oxidation occurs in the endoplasmic reticulum at a stage when the nascent polypeptide is not yet folded. The aldehyde is part of the catalytic site and is likely to act as an aldehyde hydrate. One of the geminal hydroxyl groups accepts the sulfate during sulfate ester cleavage leading to the formation of a covalently sulfated enzyme intermediate. The other hydroxyl is required for the subsequent elimination of the sulfate and regeneration of the aldehyde group. In some prokaryotic members of the sulfatase gene family, the DNA sequence predicts a serine residue, and not a cysteine. Analysis of one of these prokaryotic sulfatases, however, revealed the presence of the C alpha-formylglycine indicating that the aldehyde group is essential for all members of the sulfatase family and that it can be generated from either cysteine or serine.
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PMID:A novel protein modification generating an aldehyde group in sulfatases: its role in catalysis and disease. 969 62

Sulfatases carry at their catalytic site a unique post-translational modification, an alpha-formylglycine residue that is essential for enzyme activity. Formylglycine is generated by oxidation of a conserved cysteine or, in some prokaryotic sulfatases, serine residue. In eukaryotes, this oxidation occurs in the endoplasmic reticulum during or shortly after import of the nascent sulfatase polypeptide. The modification of arylsulfatase A was studied in vitro and was found to be directed by a short linear sequence, CTPSR, starting with the cysteine to be modified. Mutational analyses showed that the cysteine, proline and arginine are the key residues within this motif, whereas formylglycine formation tolerated the individual, but not the simultaneous substitution of the threonine or serine. The CTPSR motif was transferred to a heterologous protein leading to low-efficient formylglycine formation. The efficiency reached control values when seven additional residues (AALLTGR) directly following the CTPSR motif in arylsulfatase A were present. Mutating up to four residues simultaneously within this heptamer sequence inhibited the modification only moderately. AALLTGR may, therefore, have an auxiliary function in presenting the core motif to the modifying enzyme. Within the two motifs, the key residues are fully, and other residues are highly conserved among all known members of the sulfatase family.
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PMID:Sequence determinants directing conversion of cysteine to formylglycine in eukaryotic sulfatases. 1020 63


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