Glycosylation of proteins

Genes and proteins Animal lectin genes BPGD 

Glycosyl pathways http //www.functionalglycomics.org/static/gt/gtdb.shml GlyProt http //www.dkfz-heidelberg.de/spec/glyprot/php/ 

Animal lectin genomics resources Bacterial PolyS genes 3D structures of lectins Carbohydrate active enzymes Glycan binding proteins 

Navigation of gjycoenzymes In silica glycosylation of proteins (input 3D) 

Note Abbreviations used GS, glycosylation sites polyS, polysaccharides. 

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Under certain conditions glucose molecules can induce free-radical production (see section on non-enzymatic glycosylation of protein). 

Carbohydrates play a major role in protein bioactivity, bioavailability, and antigenicity therefore, the understanding of the glycosylation of protein molecules is very important in the development of effective glycoprotein therapeutics.172 In recent years, there has been considerable activity in the development of simple, rapid, and reliable separation methods for the analysis of... 

Serine and threonine are sites for O-linked glycosylation of proteins, a posttranslation-al modification that should be associated with the Golgi apparatus,... 

Synthesis of dolichol pyrophosphate, a required cofactor in N-hnked glycosylation of proteins in the endoplasmic reticulum... 

The cytotoxicity of fluoroaspartic acids and of fluoroasparagines, their inhibition of the biosynthesis of purines and of the glycosylation of proteins, as well as the inhibition... 

The dolichol-linked D-mannosyl, D-glucosyl, and 2-acetamido-2-deoxy-D-glucosyl residues are used in the glycosylation of proteins and in the biosynthesis of D-m an nan.2,35 GlcNAc-PP-Dol may also play a role in the synthesis of glycosaminoglycans. Reaction 4 is the first step in the formation of lipid-linked precursors for cellulose.46... 

The best known inhibitors of glycosylation of proteins interfere with the lipid-dependent steps.35,228 Substances that specifically block reactions taking place after the transfer of the oligosaccharide to the protein are little known. As several, incompletely (or differently) glycosylated, viral glycoproteins arc still biologically active (see Section IV), these substances would escape the screening procedure based on... 

Thus, the effects of glycosylation inhibitors on intact cells may also be studied best with virus-infected cells. Before release of virus, the glycoproteins are detected in the water-insoluble, membranous fraction. Furthermore, the lipid-linked oligosaccharides may be rather specifically extracted from whole cells, and monosaccharide-lipids may also be determined.3-116 It is thus seen that the various tools of virology and of lipid and carbohydrate biochemistry have proved productive in establishing the mode of action of inhibitors of lipid-depen-dent glycosylation of proteins. 

In contrast to these results, 25-hydroxycholesterol (and also, 20-hy-droxycholesterol, 7-ketocholesterol, and diosgenin) in aortic, smooth-muscle cells effectively blocks the incorporation of acetate into lipid-linked oligosaccharides (and, also, into cholesterol7). Thus, less of the lipid-linked oligosaccharides were available for glycosylation of proteins. In harmony with the presumed, inhibitory mechanism was the observation that incorporation of mevalonate into lipid-linked oligosaccharides was not inhibited, and that mevalonate itself (the product formed by HMG-CoA reductase from HMG-CoA and NADPH) could reverse the inhibition of glycosylation of protein (see Scheme 1). 

The mechanism of inhibition of glycosylation of protein by FMan has not yet been investigated in detail however, the result that residual glycosylation of protein, noted in the presence of FGlc, does not occur in the presence of FMan indicates a different inhibitory mechanism.282 Nucleotide esters of fluoro sugars have not yet been synthesized in sufficient amount to permit testing this idea. 

Because of its inhibition of the formation of Man-P-Dol and GlcNAc-PP-Dol, diumycin may be useful in attempts to discover possible roles of Glc-P-Dol in D-glucan formation, because it would block concomitant formation of D-mannan and glycosylation of proteins. 

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