Department of Biochemistry and Molecular Biology, University of Parma, Parco Area delle Scienze 23/A, 43124 Parma, Italy.
Gene. 2012 Jan 10;491(2):173-81. doi: 10.1016/j.gene.2011.09.034. Epub 2011 Oct 12.
Non-specific lipid transfer proteins belonging to LTP1 family represent the most important allergens for non pollen-related allergies to Rosaceae fruits in the Mediterranean area. Peach LTP1 (Pru p 3) is a major allergen and is considered the prototypic allergenic LTP. On the contrary, pear allergy without pollinosis seems to be under-reported when compared to other Rosaceae fruits suggesting that the as-yet-uncharacterized pear LTP1 (Pyr c 3) has in vivo a low allergenicity. We report here on the identification of four cDNAs encoding for LTP1 in pear fruits. The two isoforms exhibiting amino acid sequences most similar to those of peach and apple homologues were obtained as recombinant proteins. Such isoforms exhibited CD spectra and lipid binding ability typical of LTP1 family. Moreover, pear LTP1 mRNA was mainly found in the peel, as previously shown for other Rosaceae fruits. By means of IgE ELISA assays a considerable immunoreactivity of these proteins to LTP-sensitive patient sera was detected, even though allergic reactions after ingestion of pear were not reported in the clinical history of the patients. Finally, the abundance of LTP1 in protein extracts from pear peel, in which LTP1 from Rosaceae fruits is mainly confined, was estimated to be much lower as compared to peach peel. Our data suggest that the two isoforms of pear LTP1 characterized in this study possess biochemical features and IgE-binding ability similar to allergenic LTPs. Their low concentrations in pear might be the cause of the low frequency of LTP-mediated pear allergy.
非特异性脂质转移蛋白属于 LTP1 家族，是地中海地区蔷薇科果实非花粉相关过敏的最重要过敏原。桃 LTP1（Pru p 3）是一种主要过敏原，被认为是典型的变应原 LTP。相比之下，与其他蔷薇科果实相比，梨过敏无花粉症似乎报道较少，这表明尚未确定的梨 LTP1（Pyr c 3）在体内具有较低的变应原性。我们在此报告了在梨果实中鉴定到四个编码 LTP1 的 cDNA。获得了两种同工型，其氨基酸序列与桃和苹果同源物最相似，作为重组蛋白。这些同工型表现出与 LTP1 家族典型的 CD 光谱和脂质结合能力。此外，如先前在其他蔷薇科果实中所示，梨 LTP1 mRNA 主要存在于果皮中。通过 IgE ELISA 测定，这些蛋白对 LTP 敏感的患者血清具有相当的免疫反应性，尽管在患者的临床病史中没有报告食用梨后的过敏反应。最后，与桃皮相比，在梨皮蛋白提取物中 LTP1 的丰度估计要低得多，而 LTP1 主要局限于蔷薇科果实。我们的数据表明，本研究中鉴定的两种梨 LTP1 同工型具有与变应原性 LTP 相似的生化特征和 IgE 结合能力。它们在梨中的低浓度可能是 LTP 介导的梨过敏频率较低的原因。
