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)

Human factor VIII/von Willebrand factor protein containing 120 +/- 12 nmol of sialic acid and 135 +/- 13 nmol of galactose/mg of protein was digested with neuraminidase. The affinity of native factor VIII/von Willebrand factor and its asialo form for the hepatic lectin that specifically binds asialoglycoproteins was assessed from in vitro binding experiments. Native factor VIII/von Willebrand factor exhibited negligible affinity while binding of the asialo derivative was comparable to that observed for asialo-alpha1-acid glycoprotein. Incubation of asialo-factor VIII/von Willebrand factor with Streptococcus pneumoniae beta-galactosidase removed only 62% of the galactose but abolished binding to the purified hepatic lectin. When the asialo derivative was incubated with purified beta-D-galactoside alpha2 leads to 6 sialyltransferase and CMP-[14C]NeuAc, only 61% of the galactose incorporated [14C]NeuAc. From the known specificites of these enzymes, it is concluded that galactose residues important in lectin binding are present in a terminal Gal/beta1 leads to 4GlcNAc sequence on asialo-factor VIII/von Willebrand factor. The relative ristocetin-induced platelet aggregating activity of native, asialo-, and agalacto-factor VIII/von Willebrand factor was 100:38:12, respectively, while procoagulant activity was 100:100:103.
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PMID:Carbohydrate on human factor VIII/von Willebrand factor. Impairment of function by removal of specific galactose residues. 10 Apr 92

During studies on the Golgi apparatus immunolocalization of beta-galactoside alpha 2,6-sialyltransferase in intestinal cells, immunostaining of a number of post-Golgi apparatus structures including mucus droplets and plasma membrane were observed. In order to determine if this labeling was in fact due to sialyltransferase and not carbohydrate-specific antibodies in the polyclonal antiserum preparation, fusion protein to sialyltransferase was used to epitope purify polypeptide-specific antibodies. The affinity purification was performed on a column containing a beta-galactosidase-sialyltransferase fusion protein expressed in Escherichia coli. Using such antibodies we present evidence that in intestinal cells sialyltransferase is not only present in the Golgi apparatus cisternal stack but also its transtubular network and various post-Golgi apparatus structures. In absorptive enterocytes, post-Golgi apparatus vesicles, the brush border and basolateral plasma membrane, multivesicular bodies, and lysosome-like structures were labeled. In goblet cells the limiting membrane and lumen of forming and mature mucus droplets as well as the plasma membrane exhibited label for sialyltransferase. The results provide evidence for "ecto-sialyltransferase" in the plasma membranes of these cells, and suggest that most of the sialyltransferase is released from the Golgi membranes and becomes secreted with the goblet cell mucus. In addition, the polypeptide epitope-purified antibody was also used to examine regional expression of sialyltransferase in the rat intestinal epithelium. Immunolabel was restricted to the large intestine and not found in duodenum, jejunum, and ileum. Direct measurement of the enzyme activity was found to correlate with the immunoelectron microscopic data. This observation suggests that there is regional specific expression of the beta-galactoside alpha 2,6-sialyltransferase.
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PMID:Post-Golgi apparatus localization and regional expression of rat intestinal sialyltransferase detected by immunoelectron microscopy with polypeptide epitope-purified antibody. 245 61

The subcellular distribution of sialyltransferase and its product of action, sialic acid, was investigated in the undifferentiated cells of the rat intestinal crypts and compared with the pattern observed in the differentiated cells present in the surface epithelium. Sialyltransferase was immunocytochemically detected with an antibody, affinity-purified on a beta-galactosidase/sialyltransferase fusion protein, which recognizes only protein epitopes of the enzyme. A similar pattern and intensity of immunolabeling were observed in the Golgi apparatus, apical and basolateral plasma membranes of both undifferentiated and differentiated absorptive cells. However, in the goblet cells, the mucus was only weakly labeled in cells present in the basal portion of the crypts but increased in intensity through the zone of migration to the surface epithelium. Sialic acid as detected with the Limax flavus lectin was observed in the Golgi apparatus and post-Golgi apparatus structures of both absorptive and goblet cells regardless of their position along the crypt-to-surface epithelium axis. However, a striking difference in the plasma membrane distribution of sialic acid existed between undifferentiated cells of the lower half of the crypts and those of the upper half and the surface epithelium: in the former, label was present in both the apical and basolateral domain, whereas in the latter it became restricted to the apical domain. These results suggest that the presence of sialyltransferase immunoreactivity in the goblet cell mucus and the polarization of sialic acid to the apical plasma membrane of both goblet and absorptive cells may be markers for the differentiated state.
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PMID:Alteration in sialyltransferase and sialic acid expression accompanies cell differentiation in rat intestine. 245 28

Fluorescein isothiocyanate (FITC)-labelled asialotransferrin and pyridyl aminated oligosaccharides were prepared from asialotransferrin and human milk using affinity chromatography and high performance liquid chromatography (HPLC), respectively. These substances were incubated with galactosidase or sialyltransferase and then examined by lectin affinity HPLC. The elution patterns changed according to the period of incubation and amount of enzyme. This analytical method using lectin affinity HPLC with fluorescence labelled glycoprotein or oligosaccharides as the substrates has great value for detecting these enzyme under the same chromatographic conditions. In addition, differences were noted in the activity of beta-galactosidase toward oligosaccharides having the Gal beta(1----3)GlcNAc or Gal beta(1----4)GlcNAc structure at reducing termini.
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PMID:Rapid assay of beta-galactosidase and sialyltransferase by lectin affinity high performance liquid chromatography with fluorescence detection. 250 11

It was previously shown that reductive alkali treatment of purified human cervical mucin releases a heterogeneous population of reduced neutral, sialylated, and sulfated oligosaccharides (Yurewicz, E. C., and Moghissi, K. S. (1981) J. Biol. Chem. 256, 11895-11904). Four major sialylated oligosaccharide fractions were isolated with approximate compositions of Fuc:GlcNac:Gal:NeuAc:N-acetylgalactosaminitol (GalNAcol) = 0:0:0:1:1 (B1a), 0:0:1:1:1 (B2b), 0:1:2:1:1 (B3a), and 1:1:2:1:1 (B4a), where Fuc is fucose. They comprised roughly 3, 11, 7, and 6% of recovered oligosaccharide chains, respectively. On the basis of periodate oxidations, methylation analyses, and sequential degradations with glycosidases, the following structures were determined. (Formula: see text) Oligosaccharides 1 and 2 are characterized by the presence of N-acetylneuraminic acid in alpha 2,6-linkage to N-acetylgalactosaminitol. The remaining oligosaccharides contain N-acetylneuraminic acid in alpha 2,3-linkage to galactose residues. Oligosaccharides 3 and 4 and oligosaccharides 5 and 6 were isolated as unresolved isomeric mixtures in fractions B3a and B4a, respectively. Oligosaccharides 3 and 4 were distinguished on the basis of susceptibility to digestion with Aspergillus niger beta-galactosidase whereas oligosaccharides 5 and 6 were distinguished on the basis of differential rates of digestion with beef kidney alpha-fucosidase. The structural data indicate the presence of at least two sialyltransferases in human cervical epithelium and further suggest a potential physiologically significant competition between sialyltransferase and beta-N-acetylglucosaminyltransferase for C-6 of the N-acetylgalactosamine residue O-glycosidically linked to serine/threonine of the polypeptide core.
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PMID:Structural studies of sialylated oligosaccharides of human midcycle cervical mucin. 355 66

1. The following fractions were prepared from rat kidney and characterized ultrastructurally, biochemically and enzymically: (a) an ordinary rough microsomal (RM(1)) fraction; (b) a special rough microsomal (RM(2)) fraction enriched seven- to nine-fold in acid hydrolases over the homogenate; (c) a smooth microsomal (SM) fraction; (d) a Golgi (GM) fraction enriched 2.5-fold in acid hydrolases and 10-, 15- and 20-fold in sialyltransferase, N-acetyl-lactosamine synthetase and galactosyltransferase respectively; (e) a lysosomal (L) fraction enriched 15- to 23-fold in acid hydrolases. The frequency of Golgi sacs and tubules seen in the electron microscope and the specific activity of the three glycosyltransferases in these fractions increased in the order: RM(2)<RM(1)<SM<GM. 2. Five lysosomal hydrolases, acid phosphatase, beta-N-acetyl-hexosaminidase, beta-galactosidase, beta-glucuronidase and arylsulphatase, were characterized in these fractions with respect to (a) solubility on freeze-thawing and (b) electrophoretic mobility in polyacrylamide gels. 3. In the RM(2) fraction each of these hydrolases occurred largely or exclusively as a single bound basic form coincident with cationic glycoprotein bands in gels (Goldstone et al., 1973). 4. In the L fraction these hydrolases were present largely as soluble, acidic (anionic) forms. 5. The solubility, electrophoretic heterogeneity and anodic mobility of these hydrolases increased progressively in subcellular fractions in the order: RM(2)<RM(1)<SM<GM<L. 6. These findings, together with evidence cited in the text showing that N-acetylneuraminic acid residues are responsible for the solubility and electronegative charge of these acidic forms and incorporation of these residues into the Golgi apparatus, support the following scheme for the biosynthesis of lysosomal enzymes. Each hydrolase is synthesized as a bound basic glycoprotein enzyme in a restricted portion of the rough endoplasmic reticulum. The soluble, acidic forms are generated as the nascent glycoprotein enzymes migrate through the Golgi apparatus through the attachment of sugar sequences containing N-acetylneuraminic acid.
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PMID:Physicochemical modifications of lysosomal hydrolases during intracellular transport. 472 40

A cytokine preparation from rat peritoneal exudate cells was studied. The preparation was pronase sensitive and heat labile, but was insensitive to trypsin treatment. Administration to rats resulted in elevated serum levels of alpha 1-acid glycoprotein, sialyltransferase activities and cortisol, but depressed serum albumin levels; in addition, hepatic sialyltransferase activities were increased and hepatic beta-galactosidase and beta-N-acetylhexosaminidase activities were depressed.
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PMID:Studies on rat cytokines as mediators of the acute phase response. 634 Jun 81

Beta 1,4 galactosyl- and alpha 2,6 sialyltransferase (gal-T EC 2.4.1.22 and sialyl-T EC 2.4.99.1) sequentially elongate and terminate complex N-glycan chains of glycoproteins. Both enzymes reside in trans Golgi cisternae; their ultrastructural relationship, however, is unknown. To delineate their respective Golgi compartment(s) we conducted a double label immunofluorescent study by conventional and confocal laser scanning microscopy in HepG2, HeLa, and other cells in presence of Golgi-disturbing agents. Polyclonal, peptide-specific antibodies to human sialyl-T expressed as a beta-galactosidase-sialyl-T fusion protein in E. coli were developed and applied together with mABs to human milk gal-T. In untreated HepG2 and HeLa cells Golgi morphology identified by immunofluorescent labeling of sialyl-T and gal-T, respectively, was nearly identical. Treatment of cells with brefeldin A (BFA) led to rapid and coordinated disappearance of immunostaining of both enzymes; after BFA washout, vesicular structures reappeared which first stained for gal-T followed by sialyl-T; in the reassembled Golgi apparatus sialyl-T and gal-T were co-localized again. In contrast, monensin treatment produced a reversible swelling and scattering of gal-T positive Golgi elements while sialyl-T positive structures showed little change. Treatment with nocodazole led to dispersal of Golgi elements in which gal-T and sialyl-T remained co-localized. Treatment with chloroquine affected Golgi structures less than monensin and led to condensation of gal-T positive and to slight enlargement of sialyl-T positive structures. Sequential recovery from BFA of gal-T and sialyl-T and their segregation by monensin suggest that these enzymes are targeted to different Golgi subcompartments.
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PMID:Double immunofluorescent staining of alpha 2,6 sialyltransferase and beta 1,4 galactosyltransferase in monensin-treated cells: evidence for different Golgi compartments? 769 43

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

A cDNA clone encoding a new type of GalNAc alpha 2,6-sialyltransferase (ST6GalNAc II) with a structure similar to that of a previously cloned GalNAc alpha 2,6-sialyltransferase (ST6GalNAc I; Kurosawa, N., Hamamoto, T., Lee, Y.-C., Nakaoka, T., Kojima, N., and Tsuji, S. (1994) J. Biol. Chem. 269, 1402-1409) was obtained from chicken testes. The predicted amino acid sequence of ST6GalNAc II encodes a protein with type II transmembrane topology, as found for other glycosyltransferases, and showed 32% identity with that of ST6GalNAc I. Transfection of the full length ST6GalNAc II gene into COS cells led to GalNAc alpha 2,6-sialyltransferase activity with a different substrate specificity from that of ST6GalNAc I. Moreover, asialofetuin after treatment with beta-galactosidase did not serve as an acceptor for this enzyme. 14C-Sialylated oligosaccharides obtained from resialylated asialobovine submaxillary mucin with this enzyme were identical to Gal beta 1,3([14C]NeuAc alpha 2,6)GalNAc-ol but not [14C]NeuAc alpha 2,6GalNAc-ol. These results clearly show that the expressed enzyme is a novel type of sialyltransferase that requires beta-galactoside residues linked to GalNAc residues, whereas sialic acid residues linked to galactose residues are not essential for the activity.
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PMID:Cloning and expression of Gal beta 1,3GalNAc-specific GalNAc alpha 2,6-sialyltransferase. 803 63


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