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

---

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

The genome of pseudorabies virus (PrV) encodes at least seven glycoproteins. The glycoprotein complex gII consists of three related polypeptides, two of them derived by proteolytic cleavage from a common precursor and linked via disulfide bonds. It is homologous to herpes simplex virus (HSV) gB and is therefore thought to be essential for PrV replication, as is gB for HSV replication. To isolate PrV mutants deficient in gII expression, we established cell lines that stably carry the PrV gII gene. Line N7, of Vero cell origin, contains the gII gene under its own promoter and expresses gII after transactivation by herpesviral functions after infection. MDBK-derived line MT3 contains the gII gene under control of the mouse metallothionein promoter. However, it has essentially lost inducibility and constitutively produces high amounts of correctly processed glycoprotein gII. We used a beta-galactosidase expression cassette inserted into a partially deleted cloned copy of the gII gene for cotransfection with PrV DNA. gII- PrV mutants were isolated from viral progeny by taking advantage of their blue-plaque phenotype when incubated under an agarose overlay containing a chromogenic substrate. Analysis of these mutants proved that gII is indeed essential for PrV replication, since the gII- mutants grew normally on gII-complementing cells but were unable to produce plaques on noncomplementing cells. Surprisingly the PrV gII- mutants were also able to grow on a cell line constitutively expressing the gB-homologous glycoprotein gI from bovine herpesvirus 1 (BHV-1) to the same extent as on cells expressing PrV gII. gII- PrV propagated on cells expressing BHV-1 gI became susceptible to neutralization by anti-BHV-1 gI monoclonal antibodies. We also found that BHV-1 gI is present in the envelope of purified gII- pseudorabies virions grown on cells expressing BHV-1 gI, as judged by radioimmunoprecipitation and immunoelectron microscopy. These results prove that BHV-1 gI is integrated into the PrV envelope and can functionally replace glycoprotein gII of PrV.
...
PMID:Pseudorabies virus mutants lacking the essential glycoprotein gII can be complemented by glycoprotein gI of bovine herpesvirus 1. 184 88

We have used cDNA encoding the cellular receptor for poliovirus (PVR) to prepare polyclonal antisera against beta-galactosidase PVR fusion proteins. One of these antisera allowed identification of a glycoprotein doublet band of about 67 kDa in membrane preparations of HeLa cells and in a PVR cosmid-bearing mouse cell line. In vitro translation of PVR-specific transcripts gave rise to a protein of 46 kDa; the product had a molecular weight of 67 kDa when microsomal membranes were added to the cell-free extract. Overexpression of PVR cDNA in mouse L-cells by means of a recombinant vaccinia virus led to the synthesis of a glycoprotein having a molecular weight identical to that of the glycosylated in vitro product. The vaccinia virus-mediated protein was also recognized by a monoclonal antibody that blocks poliovirus infection. Its biological activity was demonstrated by poliovirus binding and infectivity assays. The data show that PVR is a glycoprotein of 67 kDa and that this protein is sufficient to confer poliovirus susceptibility to mouse cells.
...
PMID:Vaccinia virus-mediated expression and identification of the human poliovirus receptor. 185 Sep 5

Using an overlay technique, we previously showed that the Gram-negative periodontal pathogen Fusobacterium nucleatum binds to a glycoprotein of Mr 89,000 (Prakobphol, A., Murray, P., and Fischer, S.J. (1987) Anal. Biochem. 164, 5-11) in the parotid saliva of some individuals. We now show that deglycosylation of the purified glycoprotein results in loss of receptor activity. Amino acid analysis of the protein core showed predominantly proline, glycine, and glutamic acid/glutamine, a characteristic of proline-rich glycoproteins (PRG). The amino terminus contained repeating sequences of Ser-Gln-Gly-Pro-Pro-Pro-Arg-Pro-Gly-Lys-Pro-Glu-Gly-Pro-Pro-Pro- Gln-Gly that had significant compositional and sequence homology to that encoded by exon 3 of the PRB3 gene. We analyzed the PRG oligosaccharides by a combination of mass spectrometry techniques and nuclear magnetic resonance spectroscopy. Twenty-seven highly fucosylated structures were identified. The most abundant was as follows (where Fuc is fucose). (formula; see text) To understand the structural basis of F. nucleatum binding, we screened glycolipids and neoglycolipids carrying carbohydrate structures related to those of the PRG for receptor activity; components with unsubstituted terminal lactosamine residues best supported adherence. Neoglycolipids constructed from PRG oligosaccharides were also receptors. Treatment with beta-galactosidase, but not alpha-fucosidase, abolished binding, suggesting that unsubstituted lactosamine units, including the 6-antenna of the major oligosaccharide, mediate F. nucleatum adherence.
...
PMID:Structure and bacterial receptor activity of a human salivary proline-rich glycoprotein. 189 23

The tegumental glycocalyx of excysted juvenile (EJ) of Paragonimus ohirai was immunobiochemically characterized using a monoclonal antibody (MS-Mab). HPLC gel filtration showed that the antigens detected by two-site ELISA had a molecular weight of greater than or equal to 2 x 10(6) Da (dextran marker). On reduced SDS-PAGE, the glycocalyx antigen retained in the stacking gel was cleaved into several much smaller antigens after pronase treatment. The antigenic activity of the glycocalyx was stable in two-site ELISA to heat and acid treatments, but sensitive to alkali, periodate, base/borohydride, and pronase treatments. Precipitin formation in immunodouble diffusion between MS-Mab and EJ crude antigen was inhibited only by two monosaccharides: galactose and N-acetylgalactosamine. The purified glycocalyx bound strongly to PNA lectin, fairly well to RCA120 lectin, and slightly to SBA lectin, but not to Con A, WGA, UEA-1, DBA, or LFA lectins. Exo-beta-galactosidase treatment increased SBA binding, whereas it decreased PNA binding. PNA was observed to strongly bind to the body surface of living EJ. The antigenic activity of the glycocalyx was remarkably lost by incubation with exo-beta-galactosidase and O-glycanase. The glycocalyx was reactive with sera of P. ohirai-infected rats, and its reactivity was remarkably reduced by O-glycanase treatment. The ELISA level was higher in sera at an early stage of infection than in a late one. These studies show that the EJ tegumental glycocalyx is antigenic in infection, a marked, high molecular weight glycoprotein containing antigenic O-linked sugars, and that the sugar epitope is at the nonreducing terminal of the O-linked sugars and is composed of galactose and N-acetylgalactosamine.
...
PMID:Paragonimus ohirai: immunobiochemical characterization on the tegumental glycocalyx of excysted juvenile recognized by a monoclonal antibody. 190 99

Bacteroides fragilis NCDO 2217 produced a wide range of cell-associated hydrolytic enzymes (neuraminidase, alpha-fucosidase, alpha-N-acetylgalactosaminidase, beta-galactosidase, beta-N-acetylglucosaminidase) that could potentially degrade the carbohydrate moieties of mucin, a complex glycoprotein. The type of substrate used for growth markedly influenced their formation in batch cultures. Synthesis of neuraminidase, alpha-fucosidase, alpha-N-acetylgalactosaminidase and to a lesser extent, beta-N-acetylglucosaminidase, was inversely related to growth rate in continuous cultures (D = 0.03 h-1-0.23 h-1) in which porcine gastric mucin provided the sole source of carbon and nitrogen.
...
PMID:Formation of glycoprotein degrading enzymes by Bacteroides fragilis. 190 53

TIMP (tissue inhibitor of metalloproteinase) is a glycoprotein inhibitor of metalloproteinases that we hypothesize to be involved in the tissue remodeling that occurs during each hair growth cycle. We examined this hypothesis by studying the expression of TIMP at selected times during a single hair cycle using TIMP-lacZ transgenic mice to localize TIMP gene activity in the hair follicle. TIMP gene induction was visualized by staining mouse back skin for beta-galactosidase (beta-gal) activity. Paraffin sections were analyzed for the localization of TIMP expression. TIMP gene activation appears in hair follicles only during the mid-anagen (the growing stage of the hair cycle) primarily in Henle's layer of the inner root sheath. Some expression of TIMP is also seen in a few connective tissue cells, in the sebaceous gland and in cells at the proximity of the dermal papilla cells in catagen (regressing) and telogen (resting) follicles. These results are consistent with a role for TIMP in cyclic remodeling of connective tissue in hair follicles.
...
PMID:Localization of TIMP in cycling mouse hair. 190 71

Rhodopsin's oligosaccharide chains contain predominantly two types of sugar residues: mannose and N-acetylglucosamine. In the present work, bovine and rat rhodopsin were analysed biochemically for the presence of a third sugar, galactose. Treatment of bovine rod outer segments (ROS) with galactose oxidase followed by reduction with tritium-labeled sodium borohydride revealed the presence of existing molecules of galactose on rhodopsin. Rats injected intravitreally with [3H]galactose and [14C]leucine and maintained in darkness were killed 1 hr, 6 hr, 1, 3 or 5 days following the injection. Retinas were collected for subcellular fractionation and rhodopsin from each of the fractions was purified by ConA sepharose chromatography and SDS-PAGE. During the first 6 hr, galactose selectively labeled rhodopsin in the Golgi-enriched fraction resulting in increased [3H]/[14C] ratios in both Golgi and ROS. The data suggested that trimming was occurring at the transition from Golgi to ROS. Furthermore, a decrease in isotope ratio in the ROS between 6 hr and 1 day suggested further trimming of rhodopsin after membrane assembly in the ROS. Additional in vivo experiments demonstrated existing molecules of galactose on rhodopsin's oligosaccharide chain using lectin affinity chromatography. Rats injected intravitreally with [35S]methionine were dark-adapted for 2 hr. Following subcellular fractionation of retinas, ConA purified rhodopsin from ROS was applied to one of two additional lectin columns: Ricinus communis agglutinin (RCA) or Griffonia simplicifolia I (GSA). Eight to nine percent of the labeled rhodopsin was bound to and eluted from RCA, whereas none bound to GSA, indicating the presence of a beta-galactoside. The RCA agarose eluted protein co-electrophoresed with a rhodopsin standard and was light sensitive. Galactose was shown to be the terminal sugar on this subset of rhodopsin and was not capped by neuraminic acid. Binding of rhodopsin's oligosaccharide to RCA was abolished by pre-treatment with beta-galactosidase. Decreased binding of rhodopsin to RCA was observed following intravitreal injection of castanospermine but not swainsonine. Of those two inhibitors of glycoprotein trimming, only castanospermine would be expected to prevent the addition of galactose to the oligosaccharide. The association of galactose with rat rhodopsin appeared to be a transient one. At 2 hr, 8-9% of rhodopsin contained galactose, at 6 hr only 2.2% had galactose and by 24 hr less than 1% did. The galactose was trimmed from rhodopsin's oligosaccharide presumably after its role was complete. Separation of rhodopsin of the plasma membranes from rhodopsin of discs indicated that 75% of the galactose-containing rhodopsin was in the plasma membrane and only 25% was in the discs. These findings suggested a possible role for galactose in new disc formation with subsequent removal after the discs are sealed.
...
PMID:Transient hyperglycosylation of rhodopsin with galactose. 193 88

We describe the isolation and characterization of infectious pseudorabies virus (PrV) mutants expressing functional beta-galactosidase. To obtain high level expression of the enzyme, sequences of the bacterial beta-galactosidase gene starting with codon 8 were inserted in frame behind the promoter and the first seven codons of the nonessential PrV glycoprotein gX-gene. Cotransfection of this construct with viral DNA yielded PrV mutants that could be easily identified after plaque staining with a chromogenic substrate. These mutants carry the gX-beta galactosidase fusion gene inserted into the authentic gX-gene leading to loss of gX-expression. The gX-beta galactosidase fusion gene could be excised as an expression cassette and placed into other non-essential PrV genomic regions, such as the thymidine kinase gene and the glycoprotein gI-gene, resulting in inactivation of the target genes. The fusion gene remains stably integrated in the viral genome at all three locations tested. It therefore appears ideal as an insertional and easily identifiable marker and greatly facilitates isolation and purification of PrV mutants.
...
PMID:A glycoprotein gX-beta-galactosidase fusion gene as insertional marker for rapid identification of pseudorabies virus mutants. 196 40

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.
...
PMID:Rapid characterization of asparagine-linked oligosaccharides isolated from glycoproteins using a carbohydrate analyzer. 199 74

The gene for the CD4-membrane glycoprotein-receptor for HIV has been cloned. The 179 amino acids fragment of the CD4-receptor responsible for binding of gp120 HIV glycoprotein has been fused with beta-galactosidase and shown to be expressed in Escherichia coli cells. The recombinant protein in ELISA and immunoblotting techniques reacts with the monoclonal antibodies OKT4A and Leu3A known to block the interaction between the CD4 and gp120 HIV glycoprotein. The recombinant protein can be used for different scientific and practical purposes including studying of the mechanisms for HIV interaction with the sensitive cells as well as for viral gp120 protein purification, etc.
...
PMID:[Cloning and expression of the CD4 receptor gene from human T-lymphocytes in Escherichia coli cells]. 202 97


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---