title: The location and characterisation of the O-linked glycans of the human insulin receptor.
abstract: O-linked glycosylation is a post-translational and post-folding event involving exposed S/T residues at beta-turns or in regions with extended conformation. O-linked sites are difficult to predict from sequence analyses compared to N-linked sites. Here we compare the results of chemical analyses of isolated glycopeptides with the prediction using the neural network prediction method NetOGlyc3.1, a procedure that has been reported to correctly predict 76% of O-glycosylated residues in proteins. Using the heavily glycosylated human insulin receptor as the test protein six sites of mucin-type O-glycosylation were found at residues T744, T749, S757, S758, T759, and T763 compared to the three sites (T759 and T763- correctly, T756- incorrectly) predicted by the neural network method. These six sites occur in a 20 residue segment that begins nine residues downstream from the start of the insulin receptor beta-chain. This region which also includes N-linked glycosylation sites at N742 and N755, is predicted to lack secondary structure and is followed by residues 765-770, the known linear epitope for the monoclonal antibody 18-44.
authors.affiliation: Commonwealth Scientific and Industrial Research Organisation, Molecular and Health Technologies, Parkville, Victoria 3052, Australia.
authors.forename: Lindsay G
authors.initials: LG
authors.lastname: Sparrow
authors.forename: Jeffrey J
authors.initials: JJ
authors.lastname: Gorman
authors.forename: Phillip M
authors.initials: PM
authors.lastname: Strike
authors.forename: Christine P
authors.initials: CP
authors.lastname: Robinson
authors.forename: Neil M
authors.initials: NM
authors.lastname: McKern
authors.forename: V Chandana
authors.initials: VC
authors.lastname: Epa
authors.forename: Colin W
authors.initials: CW
authors.lastname: Ward
mesh_terms: D000116:Acetylgalactosamine / Q000032:analysis; D000818:Animals; D016466:CHO Cells; D002460:Cell Line; D002851:Chromatography, High Pressure Liquid; D006224:Cricetinae; D003412:Cricetulus; D000939:Epitopes / Q000276:immunology; D006020:Glycopeptides / Q000032:analysis; D006031:Glycosylation; D006801:Humans; D009004:Monosaccharide Transport Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D016571:Neural Networks, Computer; D011134:Polysaccharides / Q000032:analysis*; D011487:Protein Conformation; D011499:Protein Processing, Post-Translational; D017526:Receptor, IGF Type 1 / Q000032:analysis; D011972:Receptor, Insulin / Q000737:chemistry* / Q000235:genetics / Q000276:immunology; D011993:Recombinant Fusion Proteins / Q000032:analysis; D012694:Serine / Q000737:chemistry; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013912:Threonine / Q000737:chemistry; D000099237:UDP-Galactose Translocators
chemical_list: D000116:Acetylgalactosamine; D000939:Epitopes; D006020:Glycopeptides; D009004:Monosaccharide Transport Proteins; D011134:Polysaccharides; D017526:Receptor, IGF Type 1; D011972:Receptor, Insulin; D011993:Recombinant Fusion Proteins; D012694:Serine; D013912:Threonine; D000099237:UDP-Galactose Translocators