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 proteinuria rate and the relative clearances of beta 2-microglobulin, orosomucoid, albumin, transferrin and IgG were measured in forty-two workers exposed to cadmium and in seventy-seven control workers. A tubular type proteinuria with an increased excretion of beta 2-microglobulin and often also a glomerular type proteinuria with an increased excretion of orosomucoid, albumin, transferrin and IgG were observed mainly in workers exposed to cadmium for more than 25 years and whose cadmium concentration in blood exceeded 1 microgram Cd/100 ml and that in urine 10 microgram Cd/g creatinine. The glomerular dysfunction was also suggested by an increased plasma level of beta 2-microglobulin and creatinine. Both tubular and glomerular impairments occurred with the same prevalence and were not necessarily associated. The increased release of beta-galactosidase by the kidney suggested that cadmium can damage some epithelial cells.
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PMID:Renal excretion of proteins and enzymes in workers exposed to cadmium. 11 May 96

Complexes containing plasmid DNA, transferrin-polylysine conjugates, and polylysine-conjugated peptides derived from the N-terminal sequence of the influenza virus hemagglutinin subunit HA-2 have been used for the transfer of luciferase or beta-galactosidase marker genes to K562 cells, HeLa cells, and BNL CL.2 hepatocytes. These DNA complexes mimic the entry of viruses into cells, as they contain functions for (i) the packaging of the nucleic acid with polylysine, (ii) the attachment to the cell and receptor-mediated endocytosis with transferrin as a ligand, and (iii) the release from endosomes by using membrane-disrupting influenza peptides. The presence of these influenza peptide conjugates in the DNA complexes renders the complexes active in membrane disruption in a liposome leakage assay and results in a substantial augmentation of the transferrin-polylysine-mediated gene transfer.
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PMID:Influenza virus hemagglutinin HA-2 N-terminal fusogenic peptides augment gene transfer by transferrin-polylysine-DNA complexes: toward a synthetic virus-like gene-transfer vehicle. 151 16

We inserted a full-length murine cDNA, which had been isolated from F9 embryonal carcinoma cells by using a bovine lactose synthetase A protein cDNA as a probe, in a mammalian expression vector (pCMGT1) and expressed it in COS-1 cells to characterize the pCMGT1-directed enzyme. The galactosyltransferase activity toward asialo-agalacto-transferrin (AsAg-Tf) in the pCMGT1-transfected cells was approximately eightfold higher than that in mock- or non-transfected cells. In contrast, no difference was observed in the specific activity of galactose transfer between pCMGT1-transfected cells and mock- or non-transfected cells when asialo-ovine submaxillary mucin were used as an acceptor. Since almost all [3H]galactose incorporated into the AsAg-Tf was released by digestion with streptococcal beta-galactosidase, most of the linkage created by this enzyme was in the Gal beta 1-4GlcNAc group. The acceptor specificity of the pCMGT1-directed enzyme was changed from N-acetylglucosamine to glucose by adding alpha-lactalbumin in the reaction mixture. Alpha-Lactalbumin also partially inhibited the galactose transfer to AsAg-Tf. The kinetic study revealed that the apparent Km values of the pCMGT1-directed enzyme for N-acetylglucosamine, AsAg-Tf and UDP-Gal are 2 mM, 60 microM and 24 microM, respectively. These results indicated that the murine cDNA isolated from F9 cells encodes an active enzyme which catalyzes not only the lactose synthesis but also the transfer of galactose to N-acetylglucosamine residues of Asn-linked sugar chains of glycoproteins in a beta 1-4 linkage.
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PMID:Characterization of a murine beta 1-4 galactosyltransferase expressed in COS-1 cells. 170 63

Chromatographic methods were developed for the separation and characterization of acidic (sialylated) and neutral (asialo-complex and high-mannose) oligosaccharides released from glycoproteins with peptide N-glycosidase F. endo-beta-N-acetylglucosaminidase F and endo-beta-N-acetylglucosaminidase H using a carbohydrate analyzer (Dionex BioLC). All the carbohydrate separations were carried out on a polymeric pellicular anion-exchange column HPIC-AS6/CarboPac PA-1 (Dionex) using only two eluants namely, 0.5 M NaOH and 3% acetic acid/NaOH pH 5.5, which were mixed with water to generate various gradients. Developed conditions for quantitative detection of carbohydrates with pulsed amperometry were necessary to obtain steady baselines at 0.1-0.3 microA output with suitable sensitivity (less than 5 pmol) in separations employing a variety of acidic and alkaline sodium acetate gradients. Oligosaccharides released from heat-denatured and trypsin-treated glycoproteins were purified initially from large-scale digestion (greater than 0.1 g) by extraction of peptide material into phenol/chloroform and finally by ion-exchange chromatography of the acqueous phase. Oligosaccharides isolated from the peptide N-glycosidase digests of bovine fetuin, human transferrin and alpha 1-acid glycoprotein gave multiple peaks in each charge group in separations based on the charge content at pH 5.5. Alkaline sodium acetate gradients were developed to obtain oligosaccharide maps of the glycoproteins within 60 min, in which separated oligosaccharides eluted in the order of neutral, mono-, di-, tri- and tetra-sialylated species based on both charge, size and structure. Baseline separations were obtained with neutral oligosaccharide types but mixtures of high-mannose and complex types were poorly resolved. The high-mannose peaks were eliminated specifically from complex oligosaccharides by digesting with alpha-mannosidase. Treatment with beta-galactosidase, beta-N-acetylglucosaminidase and alpha-mannosidase resulted in a decrease of the oligosaccharide elution times corresponding to the number of sugar residues lost, the profile of changes was highly reproducible. In contrast, treatment with alpha-L-fucosidase, endo-beta-N-acetylglucosaminidase F and endo-beta-N-acetylglucosaminidase H resulted in an increase in their corresponding oligosaccharide retention times similar to the presence of an additional sugar residue. Conditions developed for separation of the reduced oligosaccharides and also a mixture of monosaccharide to oligosaccharide containing about 15 sugar residues within 30 min were useful in determining the effect of endo- and exo-glycosidases on porcine thyroglobulin oligosaccharides. Changes in elution time of the oligosaccharides following specific glycosidase digestions combined with methylation analysis provided a rapid and sensitive tool for confirmation of the carbohydrate primary structures present in thyroglobulin.
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PMID:Rapid characterization of asparagine-linked oligosaccharides isolated from glycoproteins using a carbohydrate analyzer. 199 74

A cell-free assay to monitor receptor-mediated endocytic processes has been developed that uses biotinylated transferrin and avidin-linked beta-galactosidase as receptor-associated and fluid-phase probes, respectively (Wessling-Resnick, M., and Braell, W. A. (1990) J. Biol. Chem. 265, 690-699). The fusion of vesicles from heterologous sources can be detected in this assay: endocytic vesicles from K562 cells (a human cell line) will fuse with vesicles from Chinese hamster ovary cells. Fusion between endocytic vesicles is inhibited upon treatment with N-ethylmaleimide but can be restored by the addition of untreated cytosol from either cell type. The in vitro fusion reaction is also inhibited by the nonhydrolyzable nucleotide analogs guanosine 5'-(3-thiotriphosphate) (GTP gamma S) and adenosine 5'-(3-thiotriphosphate) (ATP gamma S). Other nonhydrolyzable guanine nucleotides are found to inhibit the in vitro reaction in the following order of potency: GTP gamma S greater than 5'-guanylyl imidodiphosphate (GTP-PNP) greater than alpha,beta-methylene GTP (GTP-PCP). The inhibitory effects of the nonhydrolyzable analogs of GTP and ATP are not additive. Moreover, excess GTP relieves the inhibition by GTP gamma S more than it relieves the inhibition by ATP gamma S, while excess ATP preferentially alleviates ATP gamma S (not GTP gamma S) inhibition. These properties suggest that the two nucleotides exert their effects at distinct points in the fusion process. Although micromolar levels of excess Ca2+ also inhibit vesicle fusion, the inhibition exerted by GTP gamma S appears to proceed via a pathway independent of the divalent cation. The GTP gamma S-sensitive step in endocytic vesicle fusion is found to occur at a mechanistic stage prior to and distinct from the N-ethylmaleimide-sensitive step of the reaction. This situation permits the accumulation of a membrane vesicle intermediate in the presence of GTP gamma S; subsequent incubation of these vesicles with cytosol and GTP restores their fusion competence. Characteristics of in vitro endocytic vesicle fusion suggest that similarities exist with steps of the fusion mechanism involved with membrane traffic events of the secretory pathway.
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PMID:Characterization of the mechanism of endocytic vesicle fusion in vitro. 212 Feb 6

A cell-free system which reconstitutes early stages of receptor-mediated endocytosis has been developed, based on detection of the association between avidin-beta-galactosidase (Av beta Gal) and biotin-transferrin (B-Tf). Initially, Av beta Gal (a fluid-phase marker) and B-Tf (receptor-bound) are internalized and delivered to a common endosomal compartment in vivo and in vitro. Subsequently, these two probes enter divergent intracellular pathways: Av beta Gal is sorted from the endosome and directed for delivery to lysosomes, whereas B-Tf is segregated away from the fluid-phase marker, remaining bound to the transferrin receptor for return to the cell surface. Using the avidin-biotin association reaction to monitor the co-localization of these two probes, we have been able to reconstruct this sorting and segregation process in a cell-free system. The in vitro reaction is time-, temperature-, and ATP-dependent, and is not affected by NH4Cl; cell-free segregation of the two probes is also sensitive to N-ethylmaleimide. As these characteristics are also properties of in vitro endocytic vesicle fusion, it is likely that the latter event is a prerequisite for the sorting and segregation process. Both the in vivo and in vitro sorting of Av beta Gal and B-Tf to their respective and distinct destinations can be followed by subcellular fractionation on Percoll gradients. Our observations provide the first evidence that the cellular mechanism to identify, sort, and sequester endocytosed material can be reconstituted in a cell-free system.
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PMID:The sorting and segregation mechanism of the endocytic pathway is functional in a cell-free system. 215 10

Rabbit alveolar macrophages which were treated at 0 degrees C with phenylarsine oxide and then incubated at 37 degrees C for 10 min exhibited a two- to threefold increase in surface receptor activity for macroglobulin.protease complexes, diferric transferrin, and mannose-terminal glycoproteins. Analysis of the concentration-dependence of ligand binding indicated that changes in ligand-binding activity were due to changes in receptor number rather than alterations in ligand-receptor affinity. Surface receptor number could also be increased by treatment of cells with three other sulfhydryl reagents, N-ethylmaleimide, p-chloromercurobenzoate, and iodoacetic acid. The increase in receptor activity was maximal after 10 min and decreased over the next hour. This decrease in cell-associated receptor activity was due to the release of large membrane vesicles which demonstrated a uniform buoyant density by isopycnic sucrose gradient centrifugation. Treatment of cells with phenylarsine oxide did not decrease the cellular content of lactate dehydrogenase or beta-galactosidase, indicating that cell integrity was maintained and lysosomal enzyme release did not occur. Our studies indicate that phenylarsine oxide treatment in the presence of extracellular Ca2+ results in the fusion of receptor-containing vesicles with the cell surface.
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PMID:Phenylarsine oxide-induced increase in alveolar macrophage surface receptors: evidence for fusion of internal receptor pools with the cell surface. 240 94

The sandwich-type immunometric assay was modified by replacing the solid phase-bound antibody with a lectin for the determination of glycoproteins carrying terminal N-acetylglucosamine residues. Microwells were coated with Bandeiraea simplicifolia II lectin and incubated with glycosylation variants of human serum glycoproteins. The bound glycoproteins were detected by time-resolved fluorometry using europium-labeled antibodies. Agalacto-derivatives of alpha 1-acid glycoprotein and transferrin obtained by neuraminidase and beta-galactosidase treatment bound to the immobilized lectin, whereas the native or desialylated glycoproteins showed no binding. The measuring range of the method for agalacto-alpha 1-acid glycoprotein was 0.01 to 10 micrograms/ml and for agalacto-transferrin 1 to 300 micrograms/ml. The binding of the agalacto-glycoproteins was totally inhibited with 1 to 10 mM N-acetylglucosamine which confirmed the specificity of the method for glycoproteins containing terminal N-acetylglucosamine residues. The results indicate that the novel lectin-immunofluorometric method is sensitive and has a wide measuring range for the determination of glycosylation variants of glycoproteins.
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PMID:A lectin-immunofluorometric assay using an immobilized Bandeiraea simplicifolia II lectin for the determination of galactosylation variants of glycoproteins. 265 80

Human transferrin was incubated with sialidase and beta-galactosidase and then examined by lectin affinity high-performance liquid chromatography (HPLC). The elution patterns were changed according to the period of incubation and the amount of enzyme. This method of studying lectin affinity HPLC using human transferrin as a substrate makes possible the rapid and important detection of glycosidase activity.
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PMID:Assay of glycosidase by lectin affinity high-performance liquid chromatography. 312 7

The expression vector lambda gt11Amp3 has been used to construct a cDNA library from rat liver polyadenylated RNA. Clones expressing antigenic determinants for rat albumin, transferrin, transthyretin, apolipoprotein E and apolipoprotein AII have been identified. Albumin clones containing cDNA inserts ranging from 0.9 kb to 1.9 kb were further identified by restriction mapping and nucleic acid sequencing. The largest insert contained the entire coding sequence for albumin. Characterization of the expressed proteins by acrylamide gel electrophoresis followed by immunological detection indicated that the proteins were produced as hybrids linked to the bacterial beta-galactosidase. A cDNA library for human liver polyadenylated RNA has also been constructed. Clones expressing antigenic determinants for human serum albumin, transferrin and apolipoproteins AI, AII, AIV and E have been isolated and their identity established by nucleotide sequencing and restriction mapping. Both rat and human serum protein cDNA clones are currently being used to study the tissue specific expression of serum proteins and for the isolation and characterization of the corresponding genes.
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PMID:Isolation and characterization of genes for blood proteins. 330 67


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