Psychiatry related information on URIDINE DIPHOSPHATE XYLOSE

• Furthermore, when the ratio of UDP-xylose to cellohexaose and the reaction time were increased, both AtXT1 and AtXT2 added a second xylosyl residue adjacent to the first, which generated dixylosylated cellohexaose [1].

High impact information on URIDINE DIPHOSPHATE XYLOSE

• We describe a new gene, fringe connection (frc), that encodes a nucleotide-sugar transporter that transfers UDP-glucuronic acid, UDP-N-acetylglucosamine and possibly UDP-xylose from the cytoplasm into the lumen of the endoplasmic reticulum/Golgi [2].
• Zeatin O-xylosyltransferase (EC 2.4.2.-) mediates the formation of O-xylosylzeatin from trans-zeatin and UDP-xylose in immature seeds of Phaseolus vulgaris [3].
• The human solute carrier gene SLC35B4 encodes a bifunctional nucleotide sugar transporter with specificity for UDP-xylose and UDP-N-acetylglucosamine [4].
• The latter shows sequence similarity to enzymes that oxidize the C-4'' position of sugar nucleotides, like UDP-galactose epimerase, dTDP-glucose-4,6-dehydratase, and UDP-xylose synthase [5].
• Mass spectrometry analysis of nucleotide sugar pools showed that the resulting mutant lacked both UDP-glucuronic acid and its downstream product, UDP-xylose, thus confirming the effect of the knockout and indicating that an alternate pathway for UDP-glucuronic acid production was not used [6].

Biological context of URIDINE DIPHOSPHATE XYLOSE

• Topography of glycosylation and UDP-xylose production [7].
• Preincubation of intact microsomes with UDP-Glc or UDP-xylose at 37 degrees C, but not at 0 degrees C, led to expansion of the microsomal UDP-sugar pool on which endogenous esterification depended, suggesting that both UDP-sugars can enter the microsomal vesicles by a temperature-dependent mechanism [8].
• Photoincorporation of [beta-32P]5-N3UDP-GlcA into bovine liver UDP-Glc dehydrogenase (EC 1.1.1.22) was saturable with an apparent Kd of 12.5 microM, and was inhibited by the known active-site effectors UDP-GlcA, UDP-Glc, and UDP-xylose [9].
• A xylogenic suspension cell culture of tobacco has been used as a source for the purification of the enzymes responsible for the oxidation of UDP-glucose to UDP-glucuronic acid and its subsequent decarboxylation to UDP-xylose [10].

Anatomical context of URIDINE DIPHOSPHATE XYLOSE

• The specific translocation rate of UDP-xylose into sealed, "right-side-out" vesicles from the Golgi apparatus was 2-5-fold higher than into sealed right-side-out vesicles from the rough endoplasmic reticulum (RER) [11].
• Both permeable and intact fibroblasts were exposed to labeled UDP-xylose, UDP-galactose, and UDP-glucuronic acid, all donors of mucopolysaccharide precursors [12].
• UDP-sugars and adenine nucleotides were extracted from freshly isolated chondrocytes and primary cell cultures and analysed by anion-exchange h.p.l.c. The pool sizes of UDP-N-acetylglucosamine, UDP-N-acetylgalactosamine, UDP-glucose-galactose, UDP-glucuronate and UDP-xylose were 2.9, 1.2, 2.5, 0.6 and 0.03 nmol/10(6) freshly isolated chondrocytes [13].
• Arabinoxylans in crop plants are the major sugar components of the cell walls, and UDP-xylose is a key substrate in the biosynthesis of xylans [14].

Associations of URIDINE DIPHOSPHATE XYLOSE with other chemical compounds

• The enzyme that transfers D-xylose from UDP-xylose to the beta-linked mannose of plant N-linked oligosaccharides was purified about 51,000-fold to apparent homogeneity from soybean microsomes [15].
• AtUTr1- MycHis does not transport GDP-mannose, GDP-fucose, CMP-sialic acid, UDP-glucuronic acid, or UDP-xylose when expressed in S. cerevisiae [16].
• Such stimulation was only apparent when microsomes had been preincubated and thereby preloaded with UMP or UDP, indicating that UMP and UDP exeted their effect on UDP-xylose uptake by trans-stimulation from the luminal side of the ER membrane [17].
• UGT2B7 catalyzed the addition of the glucose and glucuronic acid moieties to an hydroxyl group on HDCA and also possessed some capacity to use UDP-xylose as sugar donor [18].
• It was further demonstrated that dodecyl-beta-D-maltoside served as an acceptor in the transfer of xylose from UDP-xylose, indicating that the exogenous substrate behaved similarly to glycogenin itself in this regard [19].
• A approximately 200 fold increase of UDP-glucuronic acid occurred in pgsI-208 cells, demonstrating a lack of UDP-xylose-mediated control of the cytoplasmically localized UDP-glucose dehydrogenase in the mutant [20].

Gene context of URIDINE DIPHOSPHATE XYLOSE

• Biosynthesis of UDP-xylose. Cloning and characterization of a novel Arabidopsis gene family, UXS, encoding soluble and putative membrane-bound UDP-glucuronic acid decarboxylase isoforms [21].
• 6. There is no change in the apparent moleculare weight of UDP-glucose dehydrogenase on binging UDP-xylose [22].
• This stimulation was found in native microsomal vesicles as well as in the intact endoplasmic reticulum (ER) membrane, as studied in permeabilized hepatocytes, indicating the potential physiological importance of UDP-xylose in the regulation of UGT [17].
• The most probable kinetic mechanism for the xylosyltransferase reaction was found to be an ordered single displacement with UDP-xylose as the leading substrate and the xylosylated peptide as the first product released [23].
• The transfer of xylose from UDP-xylose to the core beta-linked mannose of N-linked oligosaccharides by beta1,2-xylosyltransferase (XylT) is a widespread feature of plant glycoproteins which renders them immunogenic and allergenic in man [24].

Analytical, diagnostic and therapeutic context of URIDINE DIPHOSPHATE XYLOSE

• 4. The markedly different titration profiles obtained on titrating enzyme and the enzyme-NAD+ complex with UDP-xylose suggests a conformational difference between these two species 5 [22].

References