| Type: | Family | Name: | Pollen allergen Lol p2 |
| Description: | Grass pollen allergy is a major human health problem throughout the world, perennial ryegrass (Lolium perenne) being one of the more important species causing such allergy. Several proteins from this grass pollen have been characterised and used to study specific serum antibody responses inindividuals allergic to pollen proteins. Such individuals often show concordant presence of serum antibodies to all three Lol p allergens. Most(~95%) possess serum IgE and/or IgG antibodies to Lol p I, and ~45% have antibodies to Lol p II and III. Both Lol p II and III are highly cross-reactive with human, goat and rabbit antibodies. However, antibodies to Lol p I are unique and do not cross-react with Lol p II and III [].The amino acid sequences of Lol p II and Lol p III are highly similar, sharing 59% identity. Both have a region of amphipathicity (residues 61-67, Lol p III numbering) that might contain sites for binding to Ia molecules or T cell receptors. This region is identical between Lol p II and III, except for an Arg-Lys substitution, and could account for the DR3 association with responsiveness to both molecules [, ]. However, althoughLol p II and III show significant structural similarities and antibody cross reactivity, it is intriguing that only Lol p III is able to inducesignificant T cell responses []. Also interesting is that immune responseto Lol p III is associated with DR5 (in addition to DR3), whereas no DR5 association is found in Lol p II. One possibility is that Lol p III has anadditional site that binds to the DR5 Ia molecule. Indeed, Lol p III has a second highly amphipathic peptide (residues 24-30, RPGDTLA), which is different and not amphipathic in Lol II []. Moreover, comparison of thesequences of DRB gene products has shown that the first hypervariable region (residues 9-13) of DR3 and DR5, and no other region, contains thesequence EYSTSTS. It is thought that this sequence in the DR beta 1 polypeptide chain is associated with the immune responsiveness to theallergen Lol p III. In addition, both allergens share similar structure with an antibody-binding fragment for Lol p I. However, Lol p II appears tocontain unique Ia recognition sites not shared with Lol p II and III. This could explain why Ab responses to the three allergens are associated withDR3 and why most Lol p II and III responders are also Lol p I responders, but Lol p I responders are not necessarily Lol p II and III responders.The structure of allergen Phl p 2 from Timothy grass () has been determined to 1.9A by X-ray crystallography [], and more recently by NMR []. The proteincontains mainly beta structures typical of the immunoglobulin-like fold. | Short Name: | Allergen_Lolp2 |
