Prediction of Glycosylation Across the Human Proteome and the Correlation to Protein Function

The addition of a carbohydrate moeity to the side chain of a residue in a protein chain in uences the physicochemical properties of the protein Gly cosylation is known to alter proteolytic resistance protein solubility stability local structure lifetime in circulation and immunogenicity Of the various forms of protein glycosylation found in eukaryotic systems the most important types are N linked O linked GalNAc mucin type and O linked GlcNAc intracellular nuclear glycosylation N linked glycosylation is a co translational process involving the transfer of the precursor oligosac charide GlcNAc Man Glc to asparagine residues in the protein chain The asparagine usually occurs in a sequon Asn Xaa Ser Thr where Xaa is not Proline This is however not a speci c consensus since not all such sequons are modi ed in the cell O linked glycosylation involves the post translational transfer of an oligosaccharide to a serine or threonine residue In this case there is no well de ned motif for the acceptor site other than the near vicinity of proline and valine residues We have developed glycosylation site prediction methods for these three types of glycosylation using arti cial neural networks that examine correla tions in the local sequence context and surface accessibility In this paper we have used glycosylation site information on human proteins to illustrate the contribution of glycosylation to protein function and assess how widespread this modi cation is across the human proteome