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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Genesine, the naked autoglucosylating protein involved in glycogen biosynthesis, was partially purified from rat liver and some of its biochemical properties were characterized. Its activity was strongly activated by Mn2+ and two-pH optimums were obtained. UDP-14C-Glc was the preferred glucosyl donor substrate, but also UDP-14C-Xyl was. It was additionally found that more than one glucose was transferred to the protein or to that alpha1,4 glucan already linked to the protein from UDP-Glc. Glucose, maltose, xylose and UDP were inhibitors of genesine activity.
Cell Mol Biol (Noisy-le-grand) 1998 May
PMID:Rat liver genesine: a biochemical approach. 962 Apr 39

Rat brain glycogen branching enzyme was partially purified in order to elucidate its mechanism of action. The alpha1,4-alpha1,6-glucan polysaccharide was synthesized using rat brain branching enzyme under two different elongation conditions: Glc-1-P and phosphorylase or UDP-Glc and glycogen synthase. The products obtained demonstrated that the cpolysaccharides synthesized (pattern of the spectra obtained in the presence of Krisman's reagent, lambda max, parameter A and R, % beta-amylolysis and degree of branching) under different incubation times are nearly constant. These results imply that the degree of branching of a polysaccharide depends only on the enzyme specificity.
Cell Mol Biol (Noisy-le-grand) 1998 May
PMID:Glycogen brain branching enzyme. 962 Apr 41

Hydrolysis of the major structural polysaccharides of plant cell walls by the aerobic soil bacterium Pseudomonas fluorescens subsp. cellulosa is attributable to the production of multiple extracellular cellulase and hemicellulase enzymes, which are the products of distinct genes belonging to multigene families. Cloning and sequencing of individual genes, coupled with gene sectioning and functional analysis of the encoded proteins have provided a detailed picture of structure/function relationships and have established the cellulase-hemicellulase system of P. fluorescens subsp. cellulosa as a model for the plant cell wall degrading enzyme systems of aerobic cellulolytic bacteria. Cellulose- and xylan-degrading enzymes produced by the pseudomonad are typically modular in structure and contain catalytic and noncatalytic domains joined together by serine-rich linker sequences. The cellulases include a cellodextrinase; a beta-glucan glucohydrolase and multiple endoglucanases, containing catalytic domains belonging to glycosyl hydrolase families 5, 9, and 45; and cellulose-binding domains of families II and X, both of which are present in each enzyme. Endo-acting xylanases, with catalytic domains belonging to families 10 and 11, and accessory xylan-degrading enzymes produced by P. fluorescens subsp. cellulosa contain cellulose-binding domains of families II, X, and XI, which act by promoting close contact between the catalytic domain of the enzyme and its target substrate. A domain homologous with NodB from rhizobia, present in one xylanase, functions as a deacetylase. Mananase, arabinanase, and galactanase produced by the pseudomonad are single domain enzymes. Crystallographic studies, coupled with detailed kinetic analysis of mutant forms of the enzyme in which key residues have been altered by site-directed mutagenesis, have shown that xylanase A (family 10) has 8-fold alpha/beta barrel architecture, an extended substrate-binding cleft containing at least six xylose-binding pockets and a calcium-binding site that protects the enzyme from thermal inactivation, thermal unfolding, and attack by proteinases. Kinetic studies of mutant and wild-type forms of a mannanase and a galactanase from P. fluorescens subsp. cellulosa have enabled the catalytic mechanisms and key catalytic residues of these enzymes to be identified.
Prog Nucleic Acid Res Mol Biol 1998
PMID:Structure and function analysis of Pseudomonas plant cell wall hydrolases. 975 22

CWH41, a gene involved in the assembly of cell wall beta-1,6-glucan, has recently been shown to be the structural gene for Saccharomyces cerevisiae glucosidase I that is responsible for initiating the trimming of terminal alpha-1,2-glucose residue in the N-glycan processing pathway. To distinguish between a direct or indirect role of Cwh41p in the biosynthesis of beta-1,6-glucan, we constructed a double mutant, alg5Delta (lacking dolichol-P-glucose synthase) cwh41Delta, and found that it has the same phenotype as the alg5Delta single mutant. It contains wild-type levels of cell wall beta-1,6-glucan, shows moderate underglycosylation of N-linked glycoproteins, and grows at concentrations of Calcofluor White (which interferes with cell wall assembly) that are lethal to cwh41Delta single mutant. The strong genetic interactions of CWH41 with KRE6 and KRE1, two other genes involved in the beta-1,6-glucan biosynthetic pathway, disappear in the absence of dolichol-P-glucose synthase (alg5Delta). The triple mutant alg5Deltacwh41Deltakre6Delta is viable, whereas the double mutant cwh41Deltakre6Delta in the same genetic background is not. The severe slow growth phenotype and 75% reduction in cell wall beta-1,6-glucan, characteristic of the cwh41Deltakre1Delta double mutant, are not observed in the triple mutant alg5Deltacwh41Deltakre1Delta. Kre6p, a putative Golgi glucan synthase, is unstable in cwh41Delta strains, and its overexpression renders these cells Calcofluor White resistant. These results demonstrate that the role of glucosidase I (Cwh41p) in the biosynthesis of cell wall beta-1,6-glucan is indirect and that dolichol-P-glucose is not an intermediate in this pathway.
Mol Biol Cell 1998 Oct
PMID:The role of glucosidase I (Cwh41p) in the biosynthesis of cell wall beta-1,6-glucan is indirect. 976 40

Hemocytes of the solitary ascidian Halocynthia roretzi released phenoloxidase in response to sheep red blood cells and yeast cells but not to latex beads. Phenoloxidase was also released from the hemocytes by treatments with zymosan and lipopolysaccharides but not with beta 1-3 glucan. EDTA scarcely inhibited the activity of phenoloxidase but inhibited the release of the enzyme. Phenoloxidase was purified from H. roretzi hemocytes by SP-Sephadex chromatography and Sephadex G-100 gel filtration. The molecular weight of the purified enzyme was estimated to be 62,000. Phenoloxidase activity was strongly inhibited by diethyldithiocarbamate, phenylthiourea and reducing agents. H. roretzi phenoloxidase was characterized as a metalloenzyme that required copper ions for the expression of full activity. The phenoloxidase showed antibacterial activity in the presence of L-(3,4-dihydroxy)-phenylalanine and H. roretzi plasma. Thus, it can be concluded that phenoloxidase released from H. roretzi hemocytes functions as a humoral factor in the defense system of H. roretzi.
Comp Biochem Physiol B Biochem Mol Biol 1998 Apr
PMID:Ascidian phenoloxidase: its release from hemocytes, isolation, characterization and physiological roles. 978 68

A high density lipoprotein (HDL) and beta-glucan binding protein (BGBP) have been found in the hemolymph of marine shrimp. These proteins are involved in the transport of lipid and the recognition of foreign matter, respectively. Similarities in the color of the proteins and the molecular mass were noted. For a detailed comparison, HDL and BGBP were purified from two shrimp species, Penaeus vannamei and Penaeus californiensis, and their biochemical characteristics determined. Both proteins from each of the shrimp species are monomeric with approximately the same molecular mass in sodium dodecyl sulfate-polyacrylamide gel electrophoresis (approximately 100-112 kDa) and contain carbohydrate and lipid. The amino acid composition is similar and there is a high degree of similarity in the N-terminus. Furthermore, they are recognized by antibodies prepared independently. These results reveal that BGBP and HDL in shrimp hemolymph are the same protein, suggesting that there is a close relationship between the ability to respond to foreign matter and the diet as a provider of essential nutrients.
Comp Biochem Physiol B Biochem Mol Biol 1998 Nov
PMID:Shrimp plasma HDL and beta-glucan binding protein (BGBP): comparison of biochemical characteristics. 997 3

It has been proposed that synthesis of beta-1,6-glucan, one of Saccharomyces cerevisiae cell wall components, is initiated by a uridine diphosphate (UDP)-glucose-dependent reaction in the lumen of the endoplasmic reticulum (ER). Because this sugar nucleotide is not synthesized in the lumen of the ER, we have examined whether or not UDP-glucose can be transported across the ER membrane. We have detected transport of this sugar nucleotide into the ER in vivo and into ER-containing microsomes in vitro. Experiments with ER-containing microsomes showed that transport of UDP-glucose was temperature dependent and saturable with an apparent Km of 46 microM and a Vmax of 200 pmol/mg protein/3 min. Transport was substrate specific because UDP-N-acetylglucosamine did not enter these vesicles. Demonstration of UDP-glucose transport into the ER lumen in vivo was accomplished by functional expression of Schizosaccharomyces pombe UDP-glucose:glycoprotein glucosyltransferase (GT) in S. cerevisiae, which is devoid of this activity. Monoglucosylated protein-linked oligosaccharides were detected in alg6 or alg5 mutant cells, which transfer Man9GlcNAc2 to protein; glucosylation was dependent on the inhibition of glucosidase II or the disruption of the gene encoding this enzyme. Although S. cerevisiae lacks GT, it contains Kre5p, a protein with significant homology and the same size and subcellular location as GT. Deletion mutants, kre5Delta, lack cell wall beta-1,6 glucan and grow very slowly. Expression of S. pombe GT in kre5Delta mutants did not complement the slow-growth phenotype, indicating that both proteins have different functions in spite of their similarities.
Mol Biol Cell 1999 Apr
PMID:Uridine diphosphate-glucose transport into the endoplasmic reticulum of Saccharomyces cerevisiae: in vivo and in vitro evidence. 1019 54

The cell wall of yeast contains a major structural unit, consisting of a cell wall protein (CWP) attached via a glycosylphosphatidylinositol (GPI)-derived structure to beta 1,6-glucan, which is linked in turn to beta 1, 3-glucan. When isolated cells walls were digested with beta 1,6-glucanase, 16% of all CWPs remained insoluble, suggesting an alternative linkage between CWPs and structural cell wall components that does not involve beta 1,6-glucan. The beta 1,6-glucanase-resistant protein fraction contained the recently identified GPI-lacking, O-glycosylated Pir-CWPs, including Pir2p/Hsp150. Evidence is presented that Pir2p/Hsp150 is attached to beta 1,3-glucan through an alkali-sensitive linkage, without beta 1,6-glucan as an interconnecting moiety. In beta 1,6-glucan-deficient mutants, the beta 1,6-glucanase-resistant protein fraction increased from 16% to over 80%. This was accompanied by increased incorporation of Pir2p/Hsp150. It is argued that this is part of a more general compensatory mechanism in response to cell wall weakening caused by low levels of beta 1,6-glucan.
Mol Microbiol 1999 Mar
PMID:The contribution of the O-glycosylated protein Pir2p/Hsp150 to the construction of the yeast cell wall in wild-type cells and beta 1,6-glucan-deficient mutants. 1020 54

Anti-tumor active polysaccharide against Sarcoma 180 was isolated by DEAE-Sepharose CL-6B and Sepharose 4B column chromatography from the hot-water soluble fraction of the mycelium of liquid-cultured Agaricus blazei mill. This polysaccharide did not react with antibodies of anti-tumor polysaccharides such as lentinan, gliforan, and FIII-2-b which is one of anti-tumor polysaccharides from Agaricus blazei. Moreover, the analyses of 13C-NMR and GC-MS suggested that this polysaccharide was preliminarily glucomannan with a main chain of beta-1,2-linked D-mannopyranosyl residues and beta-D-glucopyranosyl-3-O-beta-D-glucopyranosyl residues as a side chain. This polysaccharide was completely different from the anti-tumor polysaccharide from fruiting body of Agaricus blazei, beta-1,6-glucan.
Biochem Mol Biol Int 1999 Apr
PMID:Anti-tumor polysaccharide from the mycelium of liquid-cultured Agaricus blazei mill. 1031 24

A lectin specific for laminarin, a beta-1,3-glucan, agglutinating baker's yeast and enhancing prophenoloxidase activation by laminarin, has been purified from the cockroach, Blaberus discoidalis, serum. Purification involved gel filtration with Bio-gel P300 and affinity chromatography on blue Sepharose CL-6B and laminarin-Sepharose 4B. The purified lectin has a molecular mass estimate of 520 kDa determined by gel filtration, and approximately 80 and 82 kDa by SDS-PAGE, under non-reducing and reducing conditions, respectively. After isoelectric focusing the lectin focused as a single band at pH 4.9. The purified lectin was stained by the periodic acid/Schiff's reagent showing that it is a glycoprotein, and was deglycosylated by endo-beta-N-acetylglu-cosaminidase F. Amino acid composition analysis showed the protein is similar to previously purified beta-1,3-glucan binding proteins from other invertebrates. In electron micrographs by negative staining, the protein formed large aggregates with 'Y'-shaped 'structural units' ca. 79 x 65 nm. Immunological tests confirmed that this lectin is not related to any other lectins previously purified from the same insect. This protein appears to be part of the hexamerin family of proteins. This is one of the first reports of a hexamerin-like molecule with lectin activity.
Comp Biochem Physiol B Biochem Mol Biol 1999 Mar
PMID:Identification, purification and properties of a beta-1,3-glucan-specific lectin from the serum of the cockroach, Blaberus discoidalis which is implicated in immune defence reactions. 1037 58


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