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:3.2.1.23 (beta-galactosidase)
14,648 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The synthesis and secretion of pro-cathepsin D is increased by estrogens in MCF7 cells. We quantified the effect of estradiol on other lysosomal enzymes in order to investigate the mechanism of this hypersecretion. Precursors of beta-hexosaminidase, cathepsin B and beta-galactosidase, which are routed to lysosomes via the mannose-6-phosphate (Man-6-P) receptor, were secreted in much lower amounts than pro-cathepsin D, but their secretion was also increased by estradiol. The activity of acid phosphatase, which is routed to lysosomes via a different transmembrane mechanism, was not altered by estradiol. While estradiol stimulated gene expression of pro-cathepsin D, it had no effect on that of pro-cathepsin B. We conclude that estradiol stimulates the secretion of several lysosomal pro-enzymes in MCF7 cells, suggesting that a general mechanism is responsible for this derouting rather than a specific alteration of cathepsin D structure.
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PMID:Estradiol increases the secretion by MCF7 cells of several lysosomal pro-enzymes. 222 57

Three lysosomal hydrolases, beta-galactosidase, beta-glucuronidase, and beta-N-acetylglucosaminidase, were examined in blood-derived macrophages and media of two patients with I-cell disease. The activities of the three enzymes were lower in I-cell macrophages than in normal controls. However, the media collected from these cells possessed higher activities than control media. beta-N-acetylglucosaminidase derived from media of I-cell macrophages was not endocytosed by fibroblasts from patients with Sandhoff's disease and was only partially endocytosed by I-cell macrophages. These findings indicate that blood-derived macrophages of patients with I-cell disease are affected. In addition, the data presented suggest the presence of two types of receptors in human blood-derived macrophages: mannose and mannose-6-phosphate.
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PMID:Lysosomal hydrolases in blood-derived macrophages of patients with I-cell disease. 309 18

The mutagenicity of urine obtained from five cigarette smokers was investigated using two bacterial assays: the Ames test and the SOS Chromotest. Urinary mutagens were extracted on Amberlite XAD-2 resin. Four urine samples showed activity towards Salmonella typhimurium tester strain TA98 with S9 mix while no SOS-inducing activity could be measured with Escherichia coli strain PQ37 in the SOS Chromotest. Using factorial design and a positive control benzo[a]pyrene (BaP), the concentration of S9, nicotinamide adenine dinucleotide phosphate (NADP) and glucose-6-phosphate (G6P) were optimized (2%, 0.5 mM and 10 mM respectively) for the SOS Chromotest. The SOS-inducing power of BaP was 1.42/nM with the standard S9 mix and 3.26/nM with the optimized S9 mix. B buffer and the age of L-broth were found to decrease the sensitivity of beta-galactosidase assays in the SOS Chromotest. A 4000-fold urine concentrate from a smoker was finally tested using the Ames test and the modified SOS Chromotest. Mutagenic and toxic activities were found toward tester strain TA98 (+S9 mix) showing that the SOS Chromotest is not at present suitable for assaying urinary mutagens in the presence of an in vitro metabolic activating mixture.
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PMID:Applicability of the SOS Chromotest to detect urinary mutagenicity caused by smoking. 313 23

Highly purified cultures of rat astrocytes and oligodendrocytes were examined for their ability to bind and internalize lysosomal enzymes. Astrocytes displayed a saturable uptake of beta-glucosidase and beta-galactosidase. The uptake was specifically inhibited by mannose-6-phosphate but not by several other sugars or sugar phosphates, indicating that the process was mediated by mannose-6-phosphate receptors. When cells were allowed to take up 125I-beta-glucosidase for 1 hr at 37 degrees C and subcellular organelles were isolated, the enzyme was shown to comigrate with a lysosomal organelle marker enzyme, suggesting that the enzyme was targeted to lysosomes. Astrocyte receptors were probed directly by binding of 125I labeled beta-glucosidase to astrocyte membranes at 4 degrees C. Binding was saturable and competitively inhibited by mannose-6-phosphate. In contrast to the astrocytes, cultured oligodendrocytes showed no specific binding or uptake of the lysosomal enzymes. Immunocytochemical staining of mixed glial cultures supported the biochemical data; only the astrocytes stained positive with anti-mannose-6-phosphate receptor antibodies.
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PMID:Binding and internalization of lysosomal enzymes by primary cultures of rat glia. 316 Aug 66

The catabolite repression caused by glucose and glucose-6-phosphate has been studied for both beta-galactosidase and thiogalactoside transacetylase, the products of the operator proximal and distal cistrons of the lac operon, respectively. We find that both cistrons are affected coordinately by this form of repression. We also find that a single alteration at the lac promoter region is sufficient to abolish sensitivity to repression of both cistrons. From this, we conclude that there is only one target site for catabolite repression in the lac operon.
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PMID:Polycistronic effects of catabolite repression on the lac operon. 411 94

Ghosts of T4 bacteriophage inhibit the uptake of thiomethyl-beta-galactoside (TMG), alpha-methylglucoside, glucose-6-phosphate, and glycerol in Escherichia coli B. The transport of orthonitrophenyl-beta-galactoside (ONPG) is also inhibited to a lesser degree and without alteration of the apparent K(m) of transport. These effects of ghosts parallel those of energy poisons on these systems. However, no one energy poison can produce such pronounced inhibitory effects in all these systems. The effect of the intact phage in these systems was either absent or very slight relative to the ghost. The effect of ghosts on the uptake of TMG was not immediate; at 10 C, no effect of the ghosts was apparent for at least 2 min. This suggests that a step, more temperature dependent than the attachment of the ghost, is necessary for the inhibitory action. The intracellular level of adenosine triphosphate (ATP) in the ghost-infected cells fell to less than 25% of the control value, and the ATP lost from the cell appeared in extracellular medium. Phage, on the other hand, caused no decrease in the intracellular ATP level. This loss of ATP from the cells after ghost infection suggests an alteration of the barrier properties of the membrane so that ATP can leave the cell; however, the accessibility of extracellular ONPG to intracellular beta-galactosidase does not increase. The dissimilarity of the actions of phage and ghosts on all properties examined does not support the model that the initial events in their infections are identical but that the intact phage, unlike the ghost, can provide information for the repair of its effects.
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PMID:Metabolism of T4 bacteriophage ghost-infected cells: effect of bacteriophage and ghosts on the uptake of carbohydrates in Escherichia coli B. 493 22

The addition of 88 mM sucrose to the culture medium of human skin fibroblasts from normal subjects caused remarkable increase in the intracellular lysosomal hydrolase activities. The mechanism of this induction by sucrose loading was carefully studied with several fibroblast strains of different inherited lysosomal storage disorders. In single lysosomal hydrolase defect such as GM1-gangliosidosis, mannosidosis and Sandhoff disease, no induction of the deficient hydrolase was found with 88 mM sucrose loading. In contrast, sucrose loading caused normalization of intracellular lysosomal hydrolase activities in I-cell disease fibroblasts and cytoplasmic inclusion materials disappeared. Subsequent investigations reveal that I-cell disease cells are classified into three subgroups by the degree of hydrolase induction by sucrose loading; a high responding, an intermediate responding and a no-response group. The heterogeneity may be based upon different induction by sucrose loading of the enzyme, probably the residual phosphotransferase which is involved in the processing steps of lysosomal enzyme molecules. With the addition of mannose-6-phosphate and 10 mM NH4Cl to cultured skin fibroblasts, it was shown that sucrose loading caused increased synthesis of lysosomal enzyme proteins. The result of the test with 2,4-dinitrophenol suggests that sucrose is indeed pinocytosed by cultured human skin fibroblasts and localized in lysosomes and that this event is the essential factor to trigger the induction of lysosomal hydrolases. Simultaneous loading of both invertase and sucrose in cultured cells caused no induction of alpha-mannosidase activity. This result indicates that invertase is also pinocytosed, reaches the lysosomes and hydrolyzes sucrose in the lysosomes. Lysosomal overloading with sucrose resulted in induction of lysosomal hydrolases and invertase blocked the induction of alpha-mannosidase activity. However, some induction still exists in beta-galactosidase and alpha-fucosidase activity. Thus it is very likely that the induction of lysosomal hydrolases demands a complicated process. In this article, we investigated the effects of sucrose on the lysosomal hydrolases in cultured human skin fibroblasts of several inherited lysosomal storage disorders and normal subjects and discuss the possible mechanism of the induction of lysosomal hydrolase activities by sucrose loading.
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PMID:The effects of sucrose loading on lysosomal hydrolases. 670 43

Bovine liver beta-glucuronidase and testicular beta-galactosidase were assimilated by generalized gangliosidosis fibroblasts at respectively rates of 90 and 464 times the rate of assimilation of horseradish peroxidase. Assimilation of either of the two enzymes by the fibroblasts was saturable, suggesting the participation of receptor-mediated adsorptive endocytosis for internalization. The rate of assimilation of either enzyme was not affected by high levels of the other enzyme, suggesting that distinct receptors for each enzyme occur on the fibroblasts' cell surface. Furthermore, although assimilation of beta-galactosidase was inhibited by mannose, methyl mannosides, mannosyl alpha 1 leads to 2 mannose, and mannose-6-phosphate, these compounds did not detectably inhibit the assimilation of beta-glucuronidase. These results suggest that testicular beta-galactosidase was assimilated by the well-established phosphomannosyl recognition system. However, liver beta-glucuronidase was assimilated by a distinct, noncompeting, and as yet undefined, recognition system.
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PMID:Selective noncompetitive assimilation of bovine testicular beta-galactosidase and bovine liver beta-glucuronidase by generalized gangliosidosis fibroblasts. 676 54

The uhp-coded hexose phosphate transport system of Escherichia coli is normally induced by the presence of extracellular glucose-6-phosphate (G6P), whereas internally generated G6P does not provide a regulatory signal. Strains carrying uhp-lac operon fusions in which lac operon expression is under the control of the uhpT promoter were isolated. The direction of transcription of the uhp T gene was found to be counterclockwise on the E. coli chromosome map. The effects of added sugar phosphates on induction of beta-galactosidase and G6P uptake activities were compared in two fusion-carrying strains differing only in the presence of functional Uhp+ activity. Induction of uhp expression by G6P was equally effective in the two strains; accumulation of G6P diminished its ability to serve as an inducer. Mannose-6-phosphate was an effective competitive inhibitor of G6P uptake, but did not inhibit induction by G6P of uhp expression. No sugar phosphates were found that inhibited induction by G6P. Inorganic phosphate competitively inhibited induction by G6P whether G6P transport activity was present or not. Thus, the transport activity is not involved in the regulation of its synthesis, and these results strongly support the view that the uhp regulatory system senses only the external environment.
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PMID:Exogenous induction of the Escherichia coli hexose phosphate transport system defined by uhp-lac operon fusions. 679 54

This study demonstrates that beta-glucuronidase from rat preputial glands binds with high affinity to spermatozoa from the cauda epididymis. The binding was calcium-independent and was inhibited by mannose-6-phosphate, but not by other phosphorylated or non-phosphorylated sugars. Binding was also inhibited by alpha-mannosidase from Dictyostelium discoideum, an enzyme known to have mannose-6-phosphate as the ligand. From solubilized sperm membranes, a protein of > 200 kDa and one of 45 kDa, were absorbed to a column of D. discoideum enzyme and to a phosphomannan column respectively, and eluted with mannose-6-phosphate. According to histochemical observations at the light and the electron microscopic level, gold particles coated with the enzyme became bound to the external surface of the plasmalemma in the acrosomal region of caudal spermatozoa. Similar labelling was observed using gold particles coated with antibodies against the rat 300 kDa phosphomannosyl receptor. The existence of phosphomannosyl receptors on the sperm plasma membrane, and our previous demonstration of the presence of affinity sites for epididymal beta-galactosidase on these gametes which is inhibited by phosphofructosyl derivatives, suggest strongly that maturing spermatozoa could be a target for glycosidases secreted into the lumen of the cauda epididymis, which then become bound to these cells via different ligand-receptor systems.
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PMID:Phosphomannosyl receptors on the surface of spermatozoa from the cauda epididymis of the rat. 755 73


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