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)

Binding of the mouse IgM antibody 6C4 is lost after treatment of human free secretory component with peptide N-glycosidase F (Bakos et al. (1991) J. Immunol. 146, 162-168) or periodate, suggesting that asparagine-linked oligosaccharides contain the epitope recognized by this antibody. Inhibition of antibody binding to free secretory component by milk oligosaccharides established that lacto-N-tetraose is the minimum structure recognized by the antibody, but larger oligosaccharides with terminal Gal beta 1-3GlcNAc sequences bind with much higher affinity. Antibody binding is enhanced by substitution with the Lewis Fuc alpha 1-4 and is inhibited by Fuc alpha 1-2Gal substitution. Free secretory component, however, does not bind other antibodies that recognize Le(a) or Leb oligosaccharides, and binding is lost after digestion with a beta-galactosidase that cleaves Gal beta 1-3 linkages but not after digestion with alpha-L-fucosidase. Therefore, the major epitope recognized by 6C4 on free secretory component is probably not an asparagine-linked Le(a) oligosaccharide. The antibody also binds to human milk lactoferrin, some human mucins, and lacto-series glycolipids including III4 alpha Fuc-lactotetraosyl ceramide and lactotetraosyl ceramide. Based on affinity chromatography of oligosaccharides released from free secretory component, the epitope recognized by antibody 6C4 is present on approximately 3.5% of the asparagine-linked oligosaccharides.
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PMID:Recognition of type 1 chain oligosaccharides and lacto-series glycolipids by an antibody to human secretory component. 757

Lymphocytic beta 1,4-galactosyltransferase (beta 1,4-GalTase, EC 2.4.1.38) activity was measured in B cells using a neoglyco-protein, N-acetylglucosamine-phenylisothiocyanate-bovine serum albumin (GlcNAc-pITC-BSA), as an acceptor substrate in a novel enzyme-linked immunosorbent assay (ELISA)-based method. This assay proved to be much simpler to use than the lengthy and expensive radiochemical assays commonly used, and has the additional advantage that it specifically detects the enzyme mediating transfer via the Gal beta 1,4GlcNAc linkage. A F(ab')2 antibody against GalTase was able to specifically inhibit the reaction. Greater sensitivity for beta 1,4-GalTase activity was obtained using GlcNAc-pITC-BSA as an acceptor substrate rather than ovalbumin. Low levels of beta-galactosidase activity were detectable in lymphocyte cell lysates at acidic pH, although such activity was not detectable at the neutral pH used in the beta 1,4-GalTase activity assay. Using this assay with the GlcNAc-pITC-BSA acceptor, similar beta 1,4-GalTase activities were observed in CD19+ B cells from patients with rheumatoid arthritis (RA) to those seen in normal control individuals.
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PMID:beta 1,4-Galactosyltransferase activity in B cells detected using a simple ELISA-based assay. 757 90

GABAA receptor channels (GABARs) composed of varying combinations of alpha 1, beta 1, and gamma 2S subunits were transiently expressed in mammalian cell lines. The whole-cell patch-clamp recording technique was used to determine which combinations of GABAR subunits produced functional receptor channels and whether assembly of GABAR subunits into receptor channels followed a random or preferred sequence. To identify rapidly cells expressing GABARs, mammalian cell lines were cotransfected with combinations of GABAR subunit cDNAs and the Escherichia coli beta-galactosidase gene as a transfection marker. Positively transfected cells were identified by staining with the enzyme substrate fluorescein di-beta-galactopyranoside. Using this technique, we confirmed that functional alpha 1 beta 1 and alpha 1 beta 1 gamma 2S GABARs were assembled in transfected mouse L929 fibroblast cells, but surprisingly, functional alpha 1 gamma 2S and beta 1 gamma 2S GABARs were not expressed. It was determined that after transient transfection, levels of expressed receptors varied little among individual cells permitting comparison of absolute whole-cell GABA-evoked current values. Whole-cell currents recorded from cells coexpressing alpha 1 beta 1 gamma 2S subunits were three to four times larger than those recorded from cells coexpressing alpha 1 beta 1 subunits, and they were always enhanced by coapplied diazepam. The increase in whole-cell current was due in part to the larger single-channel current of the alpha 1 beta 1 gamma 2S GABARs. GABARs comprised of alpha 1 beta 1 gamma 2S subunits were formed preferentially over GABARs of alpha 1 beta 1 subunits alone, since only after substantially increasing the ratio of the beta 1 expression vector over the alpha 1 and gamma 2S subunit expression vectors were alpha 1 beta 1 GABARs formed in the presence of the gamma 2S subunit. These findings suggest that assembly of GABARs from constituent subunits did not proceed randomly to form all possible combinations, but that certain subunit combinations were preferred intermediates during the assembly process.
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PMID:Assembly of GABAA receptor subunits: analysis of transient single-cell expression utilizing a fluorescent substrate/marker gene technique. 768 69

The application of gene transfer techniques to organ transplantation offers the potential for modulation of immunity directly within an allograft without systemic side effects. Expression vectors and promoter elements are important determinants of gene transfer and expression. In this study, various vectors (naked plasmid DNA, retroviral vector, herpes simplex viral vector, and adenoviral vector) with various promoters (RSV-LTR, SV40, MuLV-LTR, HCMVie1) were directly compared to demonstrate the successful gene transfer and expression of beta-galactosidase in murine myoblasts in vitro and within murine heterotopic, nonvascularized cardiac isografts or allografts in vivo. Expression of transferred genes was not toxic to cells and strength of expression varied according to the type of vector. Plasmid DNA was expressed in myocytes, retroviral vector was expressed in the graft infiltrating cells, and herpes simplex and adenoviral vectors were expressed in both myocytes and graft-infiltrating cells. Preliminary studies evaluated the ability of these vectors to deliver immunologically important signals. Allografts injected with pSVTGF-beta 1, a plasmid-encoding transforming growth factor beta 1 (TGF-beta 1) under the control of the SV40 promoter, showed significant prolongation of graft survival of 26.3 +/- 2.5 days compared with 12.6 +/- 1.1 days for untreated allografts, and 12.5 +/- 1.5 days for the allografts injected with control plasmid (P < 0.05). Allografts injected with MFG-vIL-10, a retroviral vector encoding viral interleukin-10 under the control of the MuLV-LTR, showed prolongation of graft survival of 36.7 +/- 1.3 days versus 12.6 +/- 1.1 days for the untreated allograft, and 13.5 +/- 2.0 days for the allografts injected with control retroviral vector (P < 0.001). Both vectors were transcriptionally active in vivo and did not appear to have toxic effects. Gene therapy for transplantation can induce transient expression of immunologically relevant molecules within allografts that impede immune activation while avoiding the systemic toxicity of conventional immunosuppression.
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PMID:Multiple vectors effectively achieve gene transfer in a murine cardiac transplantation model. Immunosuppression with TGF-beta 1 or vIL-10. 770 73

The receptor protein for thyrotrophin (thyroid-stimulating hormone; TSH) is associated with a glycosphingolipid moiety. The protein belongs to the family of receptors that couple to guanine nucleotide binding proteins; the glycosphingolipid contains sialic acid and belongs to the family of gangliosides. This report defines the structure of the receptor ganglioside in the Fisher rat thyroid cell line (FRTL-5). Receptor protein was purified by TSH affinity chromatography from FRTL-5 cells, biosynthetically labelled with [3H]galactose and [3H]glucosamine, and resolved by SDS-PAGE. A single radiolabelled band of Mr approximately 80 kDa, corresponding to the predicted size of the cloned receptor, contained ganglioside. Gangliosides were extracted from unlabelled receptor protein after SDS-PAGE and probed on TLC plates with 125I-labelled Limax flavus agglutinin or the B subunit of cholera toxin, before and after digestion with Vibrio cholerae sialidase or beta-galactosidase. The TSH receptor (TSH-R) ganglioside belongs to the gangliotetraose family, having sialic acid attached to both galactose molecules. Its sialic acid is devoid of negative charge because of the formation of internal esterlactones. Its structure is lactonized N-acetylneuraminyl-(alpha 2-->3)galactosyl(beta 1-->3)-N-acetylgalactosaminyl(beta 1-->4)-[N-acetylneuraminyl(alpha 2-->3)]galactosyl(beta 1-->4)glucosyl(beta 1-->1)ceramide (GDla-lactone). Ganglioside lactones have not been previously described as components of thyroid cells. They are highly rigid and are more likely than their parent structures to serve as molecular recognition sites and elicit immunoreactivity. Identification of this unique ganglioside intimately associated with the TSH receptor implies that it has an integral role in receptor structure and function.
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PMID:Characterization of ganglioside associated with the thyrotrophin receptor. 773 42

Four different insect cell lines that can be used as hosts for baculovirus infection were assayed for the presence of endogenous exoglycosidases. All four cell lines, derived from Spodoptera frugiperda, Trichoplusia ni, Bombyx mori, or Malacosoma disstria, contained N-acetyl-beta-glucosaminidase, N-acetyl-beta-galactosaminidase, beta-galactosidase, and sialidase activities. Exoglycosidase activities were found in cell lysates as well as cell-free supernatants from uninfected and wild-type baculovirus infected cells. Oligosaccharide analysis of cellular glycoproteins using lectins recognizing Gal beta 1, 3GalNAc, Gal beta 1, 4GlcNAc, and NeuAc alpha 2,6Gal demonstrated that only Gal beta 1,3GalNAc was present. The demonstration that these cells contain exoglycosidases raises the possibility that the oligosaccharides of baculovirus-expressed glycoproteins are subject to enzymatic degradation.
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PMID:Insect cell hosts for baculovirus expression vectors contain endogenous exoglycosidase activity. 776 90

Endo-beta-galactosidase from Escherichia freundii cleaves linear polylactosamine structure as follows: R-GlcNAc-beta 1-3Gal-beta 1-4GlcNAc-beta 1-R' + H2O-->R-GlcNAc-beta 1-3Gal + GlcNAc-beta 1-R'. Staining with Griffonia simplicifolia agglutinin II (GSA-II) following enzyme digestion reveals the distribution of R-GlcNac-beta 1-3Gal-beta 1-4GlcNAc-beta 1-R' structures in tissue sections. In this study, the procedure was applied to formalin-fixed, paraffin-embedded tissue sections from 26 cases of papillary carcinomas including 2 follicular variants, 8 follicular carcinomas, 7 adenomas, 1 anaplastic carcinoma and 1 medullary carcinoma in order to investigate whether different types of polyactosamine-containing structure are produced in these thyroid neoplasms. Simultaneously, the susceptibility of the ABH antigens expressed in these neoplastic cells to endo-beta-galactosidase digestion was examined. Most of the papillary carcinoma cells from all the individuals examined were strongly stained by GSA-II following enzyme digestion. Without enzyme digestion, little or no reactivity with GSA-II was observed. Among other types of neoplasms, only one case of follicular carcinoma exhibited reactivity with GSA-II following enzyme digestion. ABH antigens were expressed in 22 cases of papillary carcinomas, 2 adenomas, 5 follicular carcinomas and 1 anaplastic carcinoma, and their expression was dependent on the ABO blood group of the patients. Endo-beta-galactosidase digestion resulted in the elimination of these antigens not only in papillary carcinomas but also in other neoplasms.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Histochemical differences of the lectin affinities of backbone polylactosamine structures carrying the ABO blood group antigens in papillary carcinoma and other types of thyroid neoplasm. 777 98

Serum resistance of gonococci in most patients is due to sialylation of a Gal beta 1-4GlcNAc group on a conserved 4.5 kDa lipopolysaccharide (LPS) component by host cytidine 5'-monophospho-N-acetyl neuraminic acid (CMP-NANA) catalysed by a gonococcal sialyl transferase. This sialylation is enhanced by a low M(r) factor(s) which, like CMP-NANA, is released in diffusates from high M(r) fractions obtained from sonicates dialysed at 4 degrees C. Also, as shown here, this factor(s) is released when the sonicates are dialysed at 18-20 degrees C. The enhancement of sialylation, first demonstrated using enzymes in gonococcal extracts, has been shown to occur in live gonococci and hence probably to have a role in pathogenicity. Gonococci, emerging from lag phase and incubated for 2 h with CMP-14CNANA fixed up to 90% more radiolabel than controls when the second factor(s) was present; their LPS separated by SDS-PAGE contained more radiolabel than control samples and label was not detected in any other component. Fractions with enhancing activity absorbed maximally at about 260 nm but a mixture of UDP-galactose (UDP-Gal), UDP-N-Acetyl galactosamine (UDP-GalNAc), UDP-glucose (UDP-Glc) and UDP-N-Acetyl glucosamine (UDP-GlcNAc) showed no significant enhancing activity. The enhancing action of the low M(r) fractions was unaffected by incubation with beta-galactosidase.
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PMID:Sialylation of lipopolysaccharide by CMP-NANA in viable gonococci is enhanced by low Mr material released from blood cell extracts but not by some UDP sugars. 783 May 28

T3 receptors (TRs) regulate transcription by binding to specific DNA response elements as heterodimers with the retinoid X receptors (RXRs). To study the consequences of this heterodimerization for transcriptional regulation in the absence of complications associated with its effects on DNA binding affinity, we expressed in the yeast Saccharomyces cerevisiae a chimeric protein consisting of the rat TR beta 1 ligand-binding domain fused to the DNA-binding domain of the bacterial repressor lexA (lexATR). LexATR is a weak, T3-responsive activator of a beta-galactosidase reporter gene controlled by upstream lexA-binding sites (lexA-beta-gal). In contrast, coexpression of human RXR alpha (hRXR alpha) strongly enhances both the basal and ligand-induced transcriptional activities. Both the N-terminal activation domain of RXR and sequences at the extreme C terminus of lexATR are required for this T3- and RXR-dependent transcriptional activation. The lexATR chimera was also used to characterize receptor-receptor interactions using the two-hybrid system. Coexpression of B42RXR, a fusion protein of the human RXR alpha ligand-binding domain and the B42 transcriptional activation domain, strongly increases the transcriptional activity of lexATR in the absence of T3 or 9-cis-retinoic acid. We conclude that RXR is essential for full, T3-dependent transcriptional activity of the TR in yeast, and that protein-protein interaction of TR and RXR in vivo is ligand-independent.
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PMID:A chimeric thyroid hormone receptor constitutively bound to DNA requires retinoid X receptor for hormone-dependent transcriptional activation in yeast. 783 57

Somatic mutations and drugs that either reduce beta 1-6GlcNAc-branching of N-linked oligosaccharides or block the addition of terminal sequences containing galactose and sialic acid have been shown to inhibit tumour growth and metastasis. In an attempt to further define the oligosaccharide sequences that contribute to the malignant phenotype, we have selected spontaneous wheat germ agglutinin-resistant (WGAR) mutants from highly metastatic murine lymphoid tumour cells and characterized four mutant phenotypes. Mutants were selected from VM4, a clone of the MDAY-D2 tumour cell line which had been transfected with the bacterial beta-galactosidase gene (LacZ). VM4 cells retained the malignant phenotype of MDAY-D2 and the cells expressed LacZ, which facilitated the counting of metastases as the tumour cells stained blue when incubated with 5-bromo-4-chloro-3-indolyl beta-D-galactopyranoside (X-gal). The most frequently isolated mutant was defective in the transport of UDP-Gal into the Golgi, and as previously observed for this mutation, the cells were non-metastatic and produced very slow-growing solid tumours. Mutants expressing CMP-SA hydroxylase, and consequently glycoconjugates with N-glycolylneuraminic acid (NeuNGc), remained highly metastatic, but grew more slowly than VM4 cells as s.c. tumours in mice. A novel WGAR mutant showing a large increase in Gal beta 1-4GlcNAc:alpha 2-6 sialyltransferase (SA-T) mRNA levels (ST6N) and enzyme activity was observed to be less metastatic and also grew more slowly at the s.c. site of inoculation. Finally, a fourth phenotypic class of WGAR mutants showed a complex phenotype including expression of a beta Gal-binding cell surface lectin and reduced sialylation of glycoconjugates. These results suggest that changes in either the amount, the type or linkage of sialic acid in tumour cell glycoconjugates can affect tumour growth and metastasis.
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PMID:Sialylation and malignant potential in tumour cell glycosylation mutants. 788 Nov 81


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