Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.26 (invertase)
 4,927 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Concanavalin A (Con A) was utilized free, bound to Sepharose 4 B or cross-linked to glutaraldehyde to investigate the possibility of binding this lectin to radish beta-fructosidase (E.C.3.2.1.26). The choice of cross-linked Con A as affinoadsorbent is discussed and standard conditions for binding are defined. Specificity of precipitation of this enzyme by the lectin was especially investigated. Thus, the possibility of binding was tested in the presence of high ionic strength, ethylene glycol, alpha-methyl mannoside, alpha-methyl glucoside and during periodate oxidation of the enzyme. Based on the interactions observed between beta-fructosidase and Con A under these conditions it is concluded that the saccharide binding site of the lectin is primarily involved with a secondary contribution from the hydrophobic site. The specificity of binding and the complete precipitation of beta-fructosidase activity by the insolubilized lectin imply that all beta-fructosidase activity measured in Raphanus sativus seedling extracts is linked to (a) glycoprotein form(s) of this enzyme.
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PMID:Evidence for the glycoprotein nature of radish beta-fructosidase. 43 59

Teratocarcinoma stem cells maintained in the undifferentiated state express a carbohydrate-binding component that recognizes oligomannosyl residues. This cell surface molecule is detected by a rosetta assay in which the stem cells form rosettes with glutaraldehyde-fixed trypsinized rabbit erythrocytes. Addition of simple sugars to the assay mixture has little effect, but rosette formation is inhibited by a series of mannose-rich glycoproteins (yeast invertase, yeast mannans and horseradish peroxidase). Periodate oxidation eliminates the inhibitory activity of invertase whereas pronase digestion has little effect, indicating that carbohydrate moieties are essential for inhibition. Invertase and its glycopeptide derivatives also inhibit the reaggregation of dispersed stem cells and promote the dissociation of preformed aggregates. These results suggest that intercellular adhesion of teratocarcinoma stem cels may be the consequence of the interaction of a lectin-like component detected in the rosette assay with a complementary oligosaccharide receptor on adjacent cells.
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PMID:Teratocarcinoma stem cells have a cell surface carbohydrate-binding component implicated in cell-cell adhesion. 47 26

beta-Glucanases secreted into culture fluid by protoplasts or intact cells of the yeast Saccharomyces cerevisiae were investigated for the presence of covalently linked carbohydrates. Gel filtration of the enzymes on Biogel A-1.5m showed that endo-beta-1,3-glucanase is a polydisperse enzyme of high-molecular weight which elutes in about the same volume as external yeast invertase. Exo-beta-glucanase was eluted from the gel as a much lighter enzyme. Endo-beta-1,3-glucanase added to a mixture of extracellular mannoproteins was precipitated by concanavalin A to a similar extent to mannan, invertase and acid phosphatase. Under the same conditions exo-beta-glucanase did not interact with the lectin, but was partially precipitated from the solution in the absence of foreign mannan or mannan-proteins. The results show that endo-beta-1,3-glucanase of S. cerevisiae is a mannoprotein of a similar nature to external invertase and acid phosphatase. However, exo-beta-glucanase appears to be a glycoprotein which does not contain the highly branched mannan polymer in its molecule.
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PMID:Interaction of concanavalin A with external mannan-proteins of Saccharomyces cerevisiae. Glycoprotein nature of beta-glucanases. 79 52

Ethanol feeding to rats for 40 days enhanced (p < 0.001) the activities of alkaline phosphatase, sucrase, gamma-glutamyltransferase (GTP), and p-nitrophenyl (PNP)-beta-D-galactosidase (p < 0.05) with no change in leucine amino peptidase (LAP) and PNP-beta-D-glucosidase activities in intestine compared with control rats. The activities of alkaline phosphatase, sucrase, and GTP were diminished (p < 0.01) in ethanol-fed malnourished rats. There was no change in LAP activity, but the levels of glucosidase and galactosidase were elevated under these conditions. Brush-border sialic acid, fucose, hexose, and hexosamine contents were elevated in ethanol-fed protein-deficient animals. Ethanol administration to normally fed rats elevated the membrane sialic acid and hexose contents, reduced fucose content, and had no effect on brush-border hexosamine content compared with the control group. These results are in agreement with data on lectin binding to brush borders under these conditions. Alcohol ingestion reduced the incorporation of [14C]-glucosamine into brush borders in rats maintained on an 18% protein diet but augmented the incorporation of [14C]-glucosamine and [14C]-mannose in protein-malnourished membranes. These observations suggest that nutrition status influences the sensitivity of microvillus membrane glycosylation to ethanol feeding in rat intestine.
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PMID:Chronic ethanol feeding and microvillus membrane glycosylation in normal and protein-malnourished rat intestine. 142 85

Phytohemagglutinin (PHA), the seed lectin of the common bean, accumulates in protein storage vacuoles of storage parenchyma cells in cotyledons. When expressed in yeast, PHA is efficiently targeted to the yeast vacuole [Tague and Chrispeels (1987). J. Cell Biol. 105, 1971-1979]. To identify vacuolar sorting information in PHA, a series of 3' deletions of the PHA gene were fused in-frame to a truncated yeast invertase gene. An amino-terminal portion of PHA composed of a 20-residue signal sequence and 43 residues of the mature protein efficiently targeted invertase to the yeast vacuole. Internal deletions in a short PHA-invertase fusion showed that targeting information exists between residues 14 and 23 of mature PHA. Based on examinations of three-dimensional structures of related lectins, only a portion of these residues would be available on the surface of PHA for interaction with a putative receptor. Amino acid replacements at these positions in a PHA-invertase hybrid caused secretion of the invertase. The results indicate the presence of a vacuolar targeting domain in PHA that is centered at position 19 of the mature protein. This sequence of PHA also shows sequence identity to a vacuolar sorting domain characterized in yeast carboxypeptidase Y. Single amino acid alterations in a short PHA-invertase hybrid protein that caused the highest levels of secretion introduced a glycosylation site at position 21 of PHA. This observation suggests that glycan addition may interfere with recognition of a sorting determinant. These same amino acid changes did not dramatically increase secretion in a long PHA-invertase fusion or in PHA itself. Thus, a second domain of PHA may function in concert with the first one to bring about correct targeting of PHA.
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PMID:A short domain of the plant vacuolar protein phytohemagglutinin targets invertase to the yeast vacuole. 215 75

When studying mucosal barrier function of developing animals, we noted that intestinal microvillus membranes (MVM) of newborn animals differ in their fluidity and binding characteristics to lectins compared with adult MVM. To further investigate these differences and determine whether maturation of the microvillus surface could be accelerated in utero, pregnant rats were given intraperitoneal cortisone beginning on the 17th day of gestation. Control and cortisone-treated animals were allowed to deliver normally, and the small intestines from newborns were used to isolate MVM. Microvillus membrane surface characteristics were evaluated by employing an 125I-labeled fucose-specific lectin, Ulex europeus (UEA). Changes in MVM proteins were monitored by disaccharidase activities and sodium dodecyl sulfate-polyacrylamide electrophoresis. MVM fluidity was accessed using a 5-doxyl stearic acid label and electron-spin-resonance spectroscopy. Results from these studies indicate that the birth weights of newborn rats exposed to cortisone in utero were significantly reduced; sucrase activity was prematurely induced and specific activities of lactase and maltase were enhanced in the intestines of the cortisone-treated newborns as contrasted with control animals. Furthermore, binding of 125I-UEA to MVM was greatly increased in treated animals. MVM fluidity decreased (P less than 0.001) compared with control animals and resembled the structural characteristics of more mature MVM. These results suggest that cortisone exposure in utero accelerate maturation of the microvillus surface of enterocytes.
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PMID:Development of gastrointestinal mucosal barrier. VII. In utero maturation of microvillus surface by cortisone. 299 Feb 36

CaCo-2 cells are human colonic adenocarcinoma cells which can differentiate spontaneously into enterocytes when maintained confluent for extended periods of time. Cells kept in culture for 4 days (rapidly growing), 7-9 days (early confluence) and 19-22 days (late confluence) were incubated for 24 h with L-[5,6-3H]fucose or D-[6-3H]glucosamine in order to examine the changes in glycoprotein carbohydrate structure that occur during this differentiation. Labelled glycopeptides obtained by exhaustive Pronase digestion of the cell-surface and cell-pellet fractions were fractionated on Bio-Gel P-6. A high-Mr glycopeptide fraction which was excluded from Bio-Gel P-6 was present in all cases. These glycopeptides were then fractionated by affinity chromatography on Datura stramonium agglutinin-agarose. The glycopeptides which were specifically bound to the lectin column were largely degraded by endo-beta-galactosidase, thereby indicating that they consisted of fucosylated polylactosaminoglycans. The proportion of labelled polylactosaminoglycans decreased with increasing time in culture, whereas sucrase activity, which is characteristic of differentiated enterocytes, increased. These results demonstrate that a relatively large decrease in the proportion of fucosylated polylactosaminoglycans occurs with differentiation of CaCo-2 cells.
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PMID:Differentiation-associated decrease in the proportion of fucosylated polylactosaminoglycans of CaCo-2 human colonic adenocarcinoma cells. 312 22

In order to gain information on the ability of the glycosylation system of Schizosaccharomyces pombe to process heterologous glycoproteins, the expression of Saccharomyces cerevisiae invertase in the former yeast was studied. Sc. pombe cells are able to produce enzymatically active invertase from the S. cerevisiae SUC2 gene introduced by transformation and the enzyme is glycosylated and secreted into the cell wall. However, Sc. pombe transformants do not glycosylate the heterologous enzyme as their own invertase since it is not bound by the lectin from Bandeiraea simplicifolia seeds, which indicates the absence of terminal galactose residues. Moreover, the electrophoretic mobility of the heterologous invertase is similar to that of the large enzyme from S. cerevisiae, both in its native form and after being deglycosylated with Endo H. These results suggest that the polypeptide chain of S. cerevisiae invertase is the primary factor for the glycosylation in Sc. pombe cells.
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PMID:Synthesis of Saccharomyces cerevisiae invertase by Schizosaccharomyces pombe. 329 86

The present study was undertaken to provide further evidence for mechanisms proposed for the toxicity of ingested winged bean lectin in animals: to determine its effect on activities of some hydrolases localized in the brush border membrane of the small intestine. An adaptive increase in sucrase activity of rats given a high-sucrose diet (HSD) was restrained by the addition to HSD of a lectin fraction (WBLF) isolated from raw winged beans but not by that of heated WBLF or soybean trypsin inhibitor. Restraining effects of WBLF added to HSD on time-course changes in activities of sucrase, alkaline phosphatase and leucine aminopeptidase of rats after giving HSD were similar to those of concanavalin A, which had been observed in the previous study. These results substantiate that the mechanism of the toxicity of ingested winged bean lectin involves its binding to the luminal surface of the small intestine and in turn disturbing the functional formation of the brush border membrane.
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PMID:Effect of ingested winged bean lectin on gastrointestinal function in the rat. 371 4

The apical membranes of rabbit gallbladder epithelial cells were isolated by treating the homogenate with Ca2+ or Mg2+ and centrifuging the suspension in Percoll gradient. In this way brush-border membranes were obtained with enrichment factors ranging between 10 and 20 and yields of 15-30%. A second method is described with which membranes were isolated, without any preliminary treatment, first by differential centrifugation, then with Percoll gradient; the final membrane enrichment was over 15, however the yield was very low (3%). Many possible enzymatic markers of the apical plasma membrane were investigated: L-gamma-glutamyltransferase, alkaline phosphatase, leucine aminopeptidase, sucrase. The first appears to be that of choice. Apical membrane fraction could be also evidenced by autofluorescence or by labeling with Lotus tetragonolobus lectin. Preliminary experiments showed that apical plasma membranes isolated in this way form vesicles.
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PMID:Isolation of apical plasma membrane in rabbit gallbladder epithelium by Percoll density gradient centrifugation. 381 91


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