| UPA00128 |
GDP-L-fucose biosynthesis via de novo pathway~Biosynthesis of GDP-L-fucose via de novo pathway. GDP-L-fucose, the substrate for fucosyltransferases for addition of fucose to polysaccharides or glycoproteins in both procaryotes and eucaryotes, is made from GDP-D-mannose. L-Fucose is a component of bacterial surface antigens, including the extracellular polysaccharide colanic acid produced by most Escherichia coli strains, as well as by other species of the family Enterobacteriaceae. In the de novo pathway, GDP-L-fucose is synthesized from GDP-mannose via an oxidation, an epimerization, and a reduction. These steps are catalyzed by two enzymes, GDP-mannose-4,6-dehydratase and GDP-4-keto-6 -deoxy-mannose-3,5-epimerase-4-reductase (FX in mammals). In mammals, the de novo pathway is the major route for cellular GDP-L-fucose biosynthesis in vivo. Levels of GDP-L-fucose in human hepatocellular carcinoma tissues are significantly increased compared with adjacent nontumor tissues or normal livers. (relationship between elevated FX expression and increased production of GDP-L-Fucose). |
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Unexplained |
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