Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.4.99.6 (sialyltransferase)
 1,546 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A bacterial sialyltransferase, named sialyltransferase 0160, was purified from a marine bacterium that had been isolated from seawater from Sagami Bay, Kanagawa. This strain has been identified as Photobacterium damsela, and named P. damsela JT0160. Sialyltransferase 0160 was purified 688-fold to homogeneity from the crude extract of the cells with a yield of 19% using a combination of anion exchange chromatography, hydroxyapatite chromatography, gel filtration chromatography, and affinity chromatography. The purified enzyme migrated as a single band (61 kDa) on sodium dodecyl sulfate-polyacrylamide gel. This sialyltransferase was found to be a beta-galactoside alpha 2,6-sialyltransferase [EC 2.4.99.1] which catalyzes the incorporation of NeuAc from CMP-NeuAc into the galactose residue of the carbohydrate chain at position 6 on the basis of an analysis of the enzymatic reaction products with HPLC, 1H-, 13C-NMR spectroscopy, and fast atom bombardment mass spectroscopy.
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PMID:Purification and characterization of a marine bacterial beta-galactoside alpha 2,6-sialyltransferase from Photobacterium damsela JT0160. 886 51

Multiple mRNA isoforms are generated from SIAT1, the gene encoding the beta-galactoside alpha 2,6-sialyltransferase (ST6Gal I, SiaT-1, ST6N, alpha 2,6ST). These isoforms are transcriptionally initiated from a number of physically distinct promoter regions. In human B-lymphocytic cells, two SIAT1 mRNA isoforms have been identified. In order to determine if additional SIAT1 mRNA isotypes exist, RNA from Louckes, a human cell line with the mature B-phenotype, was subjected to 5'-RACE analysis. In addition to the two previously characterized mRNA forms, three additional SIAT1 mRNA forms were identified. The new mRNA isoforms incorporate novel sequence blocks into their 5'-UT regions. The data strongly suggest that these novel sequence blocks originate from previously undocumented 5'-noncoding exons and are incorporated into mRNA by alternative splicing events and/or usage of additional transcriptional promoter regions. BLAST analysis reveals no similarity of these novel regions, Exons U, V, and W, to sequences in GenBank. The only exception is Exon V, which contains a portion of Alu, a repetitive element. The data suggest that two of these novel mRNA isotypes are likely to be minor components. However, one form may contribute significantly to the SIAT1 mRNA pool in Louckes cells.
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PMID:Novel heterogeneity exists in the 5'-untranslated region of the beta-galactoside alpha 2,6-sialytransferase mRNAs in the human B-lymphoblastoid cell line, louckes. 892 Sep 23

ST6Gal I (beta-galactoside alpha 2,6-sialyltransferase, SiaT-1, ST6N, EC 2.4.99.1) mediates the attachment of the alpha 2,6-sialyl linkage common on N-linked glycans. Previous work suggests substantial inter-species conservation in SIAT1, the gene encoding ST6Gal I. In human and in rat, hepatic-specific SIAT1 transcription is initiated at Exon I. Here we report a surprising departure in the structural organization of the murine ST6Gal I gene. By a combination of primer extension analysis, 5'-RACE analysis, and analysis of genomic sequences, we show that the murine hepatic ST6Gal I mRNA contains a novel region 5' of Exon I. This novel sequence is encoded on a discrete upstream exon, Exon H. In contrast to human and rat hepatic ST6Gal I, the murine mRNA is transcriptionally initiated at the start of Exon H. Differential mRNA blot analysis indicates that transcripts containing Exon H sequences are preferentially expressed in liver.
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PMID:Murine hepatic beta-galactoside alpha 2,6-sialyltransferase gene expression involves usage of a novel upstream exon region. 914 64

To supply alpha 2,6-sialyltransferase for the large-scale synthesis of sialoside, we investigated culture conditions for the production of sialyltransferase 0160. The addition of galactose and beef extract, and control of the pH of the culture medium were effective on the production of sialyltransferase 0160. The maximal enzyme productivity reached 550 units/L. Using a crude extract of Photobacterium damsela JT0160 cells as an enzyme source, enzymatic syntheses were performed with mono- and di-saccharides as the sialyl acceptors. It was clarified that a crude extract of P. damsela JT0160 cells can be used as an synthetic catalyst for the enzymatic synthesis of sialyloligosaccharides. Furthermore, the enzyme assay showed that sialyltransferase 0160 could transfer NeuAc to not only N-linked but also O-linked carbohydrate chains. These results indicated that an abundant supply of sialyltransferase 0160 and its broad specificity make possible the synthesis of sialoside on a large scale.
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PMID:Mass production of bacterial alpha 2,6-sialyltransferase and enzymatic syntheses of sialyloligosaccharides. 953 77

We have previously shown that costimulation of endothelial cells with IL-1 + IL-4 markedly inhibits VCAM-1-dependent adhesion under flow conditions. We hypothesized that sialic acids on the costimulated cell surfaces may contribute to the inhibition. Northern blot analyses showed that Gal beta 1-4GlcNAc alpha 2, 6-sialyltransferase (ST6N) mRNA was up-regulated in cultured HUVEC by IL-1 or IL-4 alone, but that the expression was enhanced by costimulation, whereas the level of Gal beta 1-4GlcNAc/Gal beta 1-3GalNAc alpha2,3-sialyltransferase (ST3ON) mRNA was unchanged. Removing both alpha 2,6- and alpha 2,3-linked sialic acids from IL-1 + IL-4-costimulated HUVEC by sialidase significantly increased VCAM-1-dependent adhesion, whereas removing alpha 2,3-linked sialic acid alone had no effect; adenovirus-mediated overexpression of ST6N with costimulation almost abolished the adhesion, which was reversible by sialidase. The same treatments of IL-1-stimulated HUVEC had no effect. Lectin blotting showed that VCAM-1 is decorated with alpha 2,6- but not alpha 2,3-linked sialic acids. However, overexpression of alpha 2,6-sialyltransferase did not increase alpha 2,6-linked sialic acid on VCAM-1 but did increase alpha 2,6-linked sialic acids on other proteins that remain to be identified. These results suggest that alpha 2,6-linked sialic acids on a molecule(s) inducible by costimulation with IL-1 + IL-4 but not IL-1 alone down-regulates VCAM-1-dependent adhesion under flow conditions.
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PMID:Endothelial alpha 2,6-linked sialic acid inhibits VCAM-1-dependent adhesion under flow conditions. 1045 33


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