Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.4.99.10 (sialyltransferase)
 1,547 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Four different glycolipid:glycosyltransferase activities involved in the biosynthesis in vitro of gangliosides and blood group-related glycosphingolipids have been tested in a simian virus 40-transformed glial cell culture derived from the cerebrum of a fetus with Tay-Sachs disease (TSD). The TSD cultured brain cells contained little activity of either UDP-Gal:GM2(beta 1-3)galactosyltransferase (GalT-3; EC 2.4.1.62), which catalyzes the formation of GM1a from GM2 (tay-Sachs) ganglioside, or GDP-Fuc:nLcOse4Cer (alpha 1-2)fucosyltransferase (FucT-2; EC 2.4.1.89), which catalyzes the formation of H1 glycolipid from nLcOse4Cer. These cells contained a potent inhibitor of the second reaction (catalyzed by a Golgi-rich membrane fraction from bovine spleen), whereas no inhibition of the first reaction (catalyzed by a membrane fraction from 14-day-old embryonic chicken brain) was observed. The activity of UDP-Gal:LcOse3Cer(beta 1-4)galactosyltransferase (GalT-4; EC 2.4.1.86) was 30- to 80-fold higher than the activity of GalT-3. The presence of CMP-AcNeu:nLcOse4Cer sialyltransferase activity and the absence of either GalT-3 or FucT-2 suggested a probable pathway for the synthesis of sialylneolactotetraosylceramide [GM1b(GlcNAc)] in addition to a specific blockage of GM1a ganglioside synthesis from GM2 in these TSD transformed cells.
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PMID:Differential activities of glycolipid glycosyltransferases in Tay-Sachs disease: studies in cultured cells from cerebrum. 29 63

The assembly of most of the ceramide-linked glycolipids (GSLs) in eukaryotic cells occurs in Golgi bodies. At least 18 different glycolipid:glycosyltransferases (GSL:GLTs) have been characterized, 10 of which have been solubilized. These GLTs can be classified into 2 distinct groups: 1) GLTs dedicated to either Dol-P-P-sugar(s) or ceramide-linked sugar(s); and 2) GLTs with dual loyalties (i.e., they compete with glycolipid- and glycoprotein-bound oligosaccharides). Studies with solubilized and purified GalNAcT-1 and GalNAcT-2 from embryonic chicken brains prove that GalNAcT-1 (UDP-GalNAc:GM3 beta 1-4GalNAcT) is specific for GSL, whereas GalNAcT-2 (UDP-GalNAc:Gb3 beta 1-3GalNAcT) can transfer to an oligosaccharide containing the alpha-linked terminal galactose. Similarly, GalT-3 (UDP-Gal:GM2 beta 1-3GalT) is more specific for ganglio-oligosaccharide and GalT-4 (UDP-Gal:Lc3 beta 1-4GalT) can transfer galactose to N-acetylglucosamine linked to p-nitrophenol, glycolipid or glycoprotein. Both GalT-3 and GalT-4 have been separated and purified from embryonic chicken brains. Studies with solubilized SAT-4 and SAT-3, from bovine spleen and embryonic chicken brains, respectively, suggest the existence of 2 different gene-expressed alpha 2-3SATs. The newly discovered FucT-3 (GDP-Fuc:NeuGc-iLc6-alpha 1-3FucT) from human colon carcinoma (Colo-205) has also been solubilized and separated from other GSL:GLTs. Using a new activity gel-Western blot combined technique, the molecular mass of this FucT-3 was determined to be 105 kDa.
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PMID:Solubilized glycosyltransferases and biosynthesis in vitro of glycolipids. 314 22

On the basis of our previous and present studies with embryonic chicken brain system, we have proposed stepwise biosynthesis of GD1a (Gg-series) and LD1 (Lc-series) gangliosides, starting from ceramide (Fig. 4). At least three different galactosyltransferases GalT-2 (UDP-Gal:Glc-Cer), GalT-3(UDP-Gal:GM2) and GalT-4(UDP-Gal:LcOse3-Cer) and three different sialyltransferases SAT-1(CMP-NeuAc:Lac-Cer), SAT-2(CMP-NeuAc:GM3) and SAT-3(CMP-NeuAc:nLcOse4 Cer) are involved in the biosynthesis in vitro of these gangliosides. All six of these glycosyltransferases have been solubilized using nonionic detergents. Two forms of glycolipid:galactosyltransferases (GalT-3 and GalT-4) have been separated by DEAE sepharose CL-6B chromatography from solubilized supernatant of 11- to 13-day-old embryonic chicken brain. Using microisoelectric focusing (pH gradient 3 to 8) the galactosyltransferases (GalT-3 and GalT-4) have been separated from SAT-3. Two beta-N-acetylglucosaminyltransferases (GlcNAcT-2(UDP-GlcNAc:nLcOse4Cer(beta 1-3] and GlcNAcT-3(UDP-GlcNAc:nLcOse4Cer(beta 1-6] have also been solubilized from mouse T-lymphoma, P-1798, using Triton CF-54. These enzymes are involved in the synthesis of Ii-core gangliosides and 3H-products have been characterized by methylation studies. Further separation of these two GlcNAcT's are in progress.
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PMID:Biosynthesis in vitro of gangliosides containing Gg- and Lc-cores. 643 46

This report concerns the stepwise biosynthesis in vitro of Sialyl Lewis X, (SA-Le(x)), a carcinoembryonic antigen, in human colon carcinoma KM12 cells exhibiting different metastatic behaviors. The significance of SA-Le(x) has become even more apparent since the detection of its terminal epitope NeuAc(alpha 2-3)Gal beta 1-4(Fuc alpha 1-3)GlcNAc-, as the binding ligand of the selectin family member ELAM-1. The activity level of galactosyltransferase GalT-4 which catalyzes the formation of core nLcOse4Cer (Gal beta 1-4GlcNAc beta 1-3Gal beta 1-4Glc-Cer) is very high in all the metastatic lines tested with highly metastatic lines (KM12-SM) exhibiting the highest activity. The same activity pattern for galactosyltransferase is also observed when tested with iLcOse5Cer (GlcNAc beta 1-3nLcOse4Cer), the precursor for polylactosamine glycolipid. Sialyltransferase SAT-3 which catalyzes the formation of LM1 (NeuAc alpha 2-3nLcOse4Cer), the precursor for SA-Le(x), is also present in all the metastatic cell lines although the activity levels are much lower compared to galactosyltransferase. The fucosyltransferase FucT-3, which catalyzes the formation of R'-Gal-Fuc(alpha 1-3)GlcNAc-R linkage, is active with both nonsialylated substrate, nLcOse4Cer, and sialylated substrate, LM1 (NeuAc alpha 2-3nLcOse4Cer) with the formation of either Le(x) (Gal beta 1-4(Fuc alpha 1-3)GlcNAc beta 1-3Gal beta 1-4Glc-Cer) or SA-Le(x) (NeuAc alpha 2-3nLcOse4Cer). However, the sialylated substrate LM1 is preferred to enzymatic activity since it exhibited lower Km (46 microM) than that of nLcOse4Cer (67 microM).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Biosynthesis and regulation of Le(x) and SA-Le(x) glycolipids in metastatic human colon carcinoma cells. 791 80