title: Barley γ3-hordein: glycosylation at an atypical site, disulfide bridge analysis, and reactivity with IgE from patients allergic to wheat.
abstract: Post translational modifications of a seed storage protein, barley γ3-hordein, were determined using immunochemical and mass spectrometry methods. IgE reactivity towards this protein was measured using sera from patients diagnosed with allergies to wheat. N-glycosylation was found at an atypical Asn-Leu-Cys site. The observed glycan contains xylose. This indicates that at least some γ3-hordein molecules trafficked through the Golgi apparatus. Disulfide bridges in native γ3-hordein were almost the same as those found in wheat γ46-gliadin, except the bridge involving the cysteine included in the glycosylation site. IgE reacted more strongly towards the recombinant than the natural γ3-hordein protein. IgE binding to γ3-hordein increased when the protein sample was reduced. Glycosylation and disulfide bridges therefore decrease epitope accessibility. Thus the IgE from patients sensitized to wheat cross-react with γ3-hordein due to sequence homology with wheat allergens rather than through shared carbohydrate determinants.
authors.affiliation: INRA, UMR1318, Institut Jean-Pierre Bourgin, RD10, F-78000 Versailles, France.
authors.forename: Jacques
authors.initials: J
authors.lastname: Snégaroff
authors.forename: Isabelle
authors.initials: I
authors.lastname: Bouchez
authors.forename: Mohamed El Amine
authors.initials: Mel A
authors.lastname: Smaali
authors.forename: Catherine
authors.initials: C
authors.lastname: Pecquet
authors.forename: Nadia
authors.initials: N
authors.lastname: Raison-Peyron
authors.forename: Pascale
authors.initials: P
authors.lastname: Jolivet
authors.forename: Michel
authors.initials: M
authors.lastname: Laurière
mesh_terms: D003429:Cross Reactions; D004220:Disulfides / Q000737:chemistry* / Q000276:immunology; D000939:Epitopes / Q000737:chemistry / Q000276:immunology; D005260:Female; D005512:Food Hypersensitivity / Q000276:immunology*; D005983:Glutens / Q000737:chemistry* / Q000276:immunology; D006031:Glycosylation; D001467:Hordeum / Q000737:chemistry* / Q000276:immunology; D006801:Humans; D007073:Immunoglobulin E / Q000737:chemistry* / Q000276:immunology*; D008297:Male; D014908:Triticum / Q000737:chemistry / Q000276:immunology; D014994:Xylose / Q000737:chemistry / Q000276:immunology
chemical_list: D004220:Disulfides; D000939:Epitopes; D007073:Immunoglobulin E; D005983:Glutens; D014994:Xylose