Linear IgE epitope mapping of the English walnut (Juglans regia) major food allergen, Jug r 1

Jason M. Robotham, Suzanne S Teuber, Shridhar K. Sathe, Kenneth H. Roux

Research output: Contribution to journalArticlepeer-review

90 Scopus citations


Background: Peanut and tree nut allergies can be life-threatening, and they appear to be growing in prevalence. Jug r 1, a 2S albumin seed storage protein, was previously characterized as a major English walnut food allergen. Objective: We sought to identify the linear IgE-binding epitopes of Jug r 1 and to determine which, if any, amino acids are necessary for this binding to occur. Methods: Pools of sera from walnut-allergic patients and overlapping peptides synthesized on an activated cellulose membrane were used to screen for IgE-binding epitopes. Mutational analysis of the immunodominant epitope was carried out through single and multisite amino acid substitutions. Inhibition assays were performed through use of affinity-purified IgE, soluble forms of the epitope peptide, and the recombinant 2S albumin, r Jug r 1. Results: One immunodominant linear epitope was identified. Amino acid mutations to the epitope demonstrated that the residues RGEE, at positions 36 through 39, were minimally required for IgE binding. Probing of this epitope with sera from each of 20 patients revealed 15 of the sera to be positive. Binding of patients' IgE to the epitope was inhibited with a soluble form of the peptide; however, soluble peptide did not completely inhibit the binding of IgE to the intact r Jug r 1. Conclusion: One major linear IgE-reactive epitope and its critical core amino acid residues have been identified. Mutation of any of these core amino acids resulted in loss of IgE binding to the epitope, and this points toward the feasibility of reducing allergenicity in genetically modified walnuts. However, strong evidence for the existence of conformational epitopes was also obtained.

Original languageEnglish (US)
Pages (from-to)143-149
Number of pages7
JournalJournal of Allergy and Clinical Immunology
Issue number1
StatePublished - 2002


  • 2S albumin
  • Epitope mapping
  • Food allergy
  • Jug r 1
  • Nut allergy
  • Walnut

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology


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