Seed storage protein (PubMed:15233621, PubMed:19006093, PubMed:21563837, PubMed:21735061, PubMed:22966848, PubMed:22616776, PubMed:22812192, PubMed:23411333, Ref.12, PubMed:24577577, PubMed:25209075). Does not have superoxide dismutase (SOD) activity (PubMed:31753489). Homotrimer (PubMed:19006093, PubMed:31753489). Homohexamer (PubMed:19006093). Expressed in seed (at protein level) (PubMed:15233621, PubMed:19006093, PubMed:21563837, PubMed:21735061, PubMed:22966848, PubMed:22616776, PubMed:22812192, PubMed:23411333, PubMed:24577577, PubMed:25209075, PubMed:31753489). Expressed in seed (Ref.12). Expressed during seed maturation. Expressed at three fruit developmental stages, at early stage (approximately 45 days before harvest), at middle stage (approximately 30 days before harvest) and at final harvest stage. Expressed more in ripe than in unripe seeds (Ref.12). Expressed in raw seeds (PubMed:15233621, PubMed:19006093, PubMed:22616776, PubMed:22812192, PubMed:23411333). N-glycosylated at Asn-301 mostly with xylosylated paucimannosidic-type N-glycan MMX (an N-linked glycan with beta-1,2-xylose residue in the structure) and also with MMXF (a complex N-linked glycan with alpha-1,3-fucose and beta-1,2-xylose residues in the structure). A mixture of proteolytically processed and unprocessed subunits exist. Causes an allergic reaction in human (PubMed:15233621, PubMed:19006093, PubMed:21563837, PubMed:22616776, PubMed:22812192, PubMed:34146442). Binds to IgE of patients allergic to hazelnuts (PubMed:15233621, PubMed:19006093, PubMed:21563837, PubMed:22616776, PubMed:22812192, PubMed:34146442). Natural glycosylated protein binds to IgE in 47% and recombinant (non-glycosylated) protein in 43-40% of the 65 tested adult patients from Switzerland and Germany (PubMed:15233621). Natural protein binds to IgE in 50% of the tested patients from Netherlands (PubMed:19006093). The IgE-binding of the natural protein can be decreased by glycation (Maillard reaction) of the protein at 60 and 145 (routine hazelnut roasting condition), but not at 37 degrees Celsius (PubMed:21563837). IgE-binding of the natural protein is also strongly reduced by autoclaving at 138 degrees Celsius for 15 or 30 minutes, but not by high pressure treatment alone (300 Mba, 400 Mba, 500 Mba and 600 Mba) (PubMed:22616776). Allerginicity to this protein in a birch-endemic region (Belgium) seems to be predominantly found in children with severe hazelnut allergy compared to adults or children with milder forms of hazelnut-allergy. Natural protein binds to IgE in 36%, 40% and 12.5% of the 22 preschool children, 10 schoolchildren and 8 adults tested, respectively, with systemic allergic reactions toward hazelnut. In a set of 40 patients (6 preschool children, 10 schoolchildren and 24 adults) having oral allergy symptoms, only 2 patients (of preschool age) show IgE-binding to this protein. Also, only 8% of the 24 hazelnut-allergic infants with atopic dermatitis tested show IgE reactivity to this protein (PubMed:22812192). Induces histamine release from human basophils (PubMed:15233621, PubMed:22812192). Both natural and recombinant proteins induce histamine release from human basophils in a similar manner indicating that the carbohydrate structures are not involved in IgE-binding (PubMed:15233621). Induces beta-hexosaminidase release from humanized rat basophilic leukemia (RBL) cells. Heating, with or without glucose, at 145 degrees Celsius increases the basophil degranulation capacity (PubMed:21563837). In order to protect patients that are allergic to hazelnuts, it is extremely important to find ways to detect traces amounts of hazelnut in foods that should not contain it for the food labeling and safety purposes. This protein is used in the development of these methods (PubMed:21735061, PubMed:22966848, PubMed:23411333, PubMed:24577577, PubMed:25209075). For the detection of hazelnut, a liquid chromatography tandem mass spectrometry (LC-MS/MS) method in selected reaction monitoring (SRM) mode is developed by using selected marker peptides from this protein as standards (PubMed:21735061). It is found that LC-MS/MS performs well in detecting these peptides in prepared model chocolates spiked with hazelnut. The sensitivity level is approximately 1 mg/kg (PubMed:24577577). A stable peptide (residues 395-403) from this protein is identified by MALDI-MS and it can be used as an analytical target for the development of robust quantitative analytical methods. This peptide is identifiable even when the protein goes through a number of changes at the molecular level, such as denaturation, the Maillard reaction and oxidation, reactions that typically occur during food processing (PubMed:22966848). A quantitative method is developed, where the coding DNA of this protein is first extracted based on hexadecyltrimethylammonium bromide (CTAB)-phenol-chloroform method and then detected by Real-Time PCR (RT-PCR) in commercial foods such as chocolates, biscuits, cereal snacks, cookies and nougat with 100% specificity and with 1 ppm sensitivity limit of detection of raw hazelnut. The reliability of the method is even more improved if two other hazelnut target genes (allergens Cor a 9 and Cor a 13) are amplified in addition to this one. The detection is proven to be accurate even when the quality and quantity of the DNA is greatly diminished by roasting and autoclaving. High-hydrostatic pressure treatment has no effect on DNA (PubMed:23411333). The transcription level of the gene encoding this protein is investigated by a relative quantitative RT-PCR technique in order to compare the transcript amounts between different cultivars, and in one of the cultivars also in relation to different years of harvest and ripening stages. Each hazelnut sample is classified by the Principal Components Analysis (PCA) to better interpret the results. The method may help in choosing hypoallergenic genotypes of hazelnut for both growers and consumers (Ref.12). Cold acetone extraction of proteins followed by in-solution tryptic digestion and MALDI-TOF-MS (in alpha-cyano-4-chlorocinnamic acid matrix) is found as a rapid and sensitive method to detect residual amounts of hazelnut proteins in extra virgin olive oil samples, which have been adulterated with cold-pressed hazelnut oil. Peptides from this protein can be used as stable markers in this technique serving as a direct proof of illegal hazelnut existence in olive oil (PubMed:25209075). Belongs to the 7S seed storage protein family.