Disease relevance of Xylt1

• The data suggest a participation of myofibroblasts with increased xylosyltransferase activities in accumulation of versican in fibrotic foci of injured lung tissue at the early stages of development of lung fibrosis [1].
• Purification of rat chondrosarcoma xylosyltransferase [2].

High impact information on Xylt1

• A xylosyltransferase in rat kidney, tentatively identified as glycogenin (Meezan, E., Ananth, S., Manzella, S., Campbell, P., Siegal, S., Pillion, D. J., and Rodén, L. (1994) J. Biol. Chem. 269, 11503-11508), was purified by a procedure in which affinity chromatography on UDP-glucuronic acid-agarose was a particularly useful step [3].
• The specific activity of xylosyltransferase (using silk fibroin as exogenous acceptor) was 50-100-fold higher in Golgi apparatus membranes than in those from the RER [4].
• Neither the chelator alone nor in combination with low concentrations of nucleotides was inhibitory to glycosyltransferase activities, as shown by xylosyltransferase in chick embryo epiphyseal microsomes and galactosyltransferase in rat serum [5].
• We treated confrontation Schwann cell/astrocyte cultures with the following: (1) a deoxyribonucleic acid (DNA) enzyme against the glycosaminoglycan (GAG)-chain-initiating enzyme, xylosyltransferase-1 (XT-1), (2) a control DNA enzyme, and (3) chondroitinase ABC (Ch'ase ABC) to degrade the GAG chains [6].
• A comparison of the acceptor efficiencies (Vmax/Km) of synthetic peptides containing the proposed xylosylation consensus sequence and the natural acceptor (deglycosylated core protein) was then made by use of the in vitro xylosyltransferase assay [7].

Biological context of Xylt1

• These results suggest that the artificial peptides containing the consensus sequence are analogues of individual substitution sites on the core protein and allowed the kinetic mechanism of the xylosyltransferase reaction to be investigated, with one of the artificial peptides as a model substrate [7].
• Omission of the latter exons in L-APP and L-APLP2 isoforms, respectively, generates a functional recognition sequence for xylosyltransferase-mediated addition of glycosaminoglycans and proteoglycan formation [8].
• We used a newly designed DNA enzyme, which targets the mRNA of a critical enzyme that initiates glycosylation of the protein backbone of PGs, xylosyltransferase-1 [9].

Anatomical context of Xylt1

• A procedure for purification of xylosyltransferase from rat ear cartilage was developed which includes ammonium sulfate fractionation, chromatography on heparin-agarose, on Sephacryl S300 and finally a substrate affinity chromatography applying the dodeca peptide Q-E-E-E-G-S-G-G-G-Q-G-G [10].
• Bleomycin treatment of isolated rat lung fibroblasts resulted in a concentration-dependent increase of xylosyltransferase activity up to 2 mU bleomycin x mL(-1) [1].
• Furthermore, XT activity was investigated in 21 different human cell lines [11].

Associations of Xylt1 with chemical compounds

• 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 [7].
• Changes in xylosyltransferase activity and in proteoglycan deposition in bleomycin-induced lung injury in rat [1].
• Optimal removal of xylose residues after about 1 h was also shown by maximal acceptor activity of the product in a xylosyltransferase assay [12].
• Thus, if xylosyltransferase activity is referred to the amount of galactosamine-containing proteoglycans in cartilage, nearly identical values are obtained (young rats, 80 +/- 30 Bq h-1 mumol-1 GalN; old rats, 85 +/- 35 Bq h-1 mumol-1 GalN) [13].
• The results support the assumption that the synthesis of proteochondroitin sulfate is diminished in costal cartilage of old rats by a mechanism involving a reduced activity of xylosyltransferase [13].

Analytical, diagnostic and therapeutic context of Xylt1

• Deposition of proteoglycans in lung tissue was assessed by immunohistochemistry and the catalytic activity of xylosyltransferase was determined with an acceptor peptide of the sequence Q-E-E-E-G-S-G-G-G-Q-G-G as a substrate [1].

References