Latin name: Glycine max
Source material: A native extract of allergen Gly m 6 purified from a natural Glycine max.
Common names: Legumin, 11S Globulin, G1 subunit of glycinin, G2 subunit of glycinin, G3 subunit of glycinin, G4 subunit of glycinin, G5 subunit of glycinin.
A legumin-like protein, an 11S Globulin.
Mw: 20-40 kDa
Other allergens isolated
Soya protein consists of 136 phytochemicals and at least 21 allergenic proteins that have been identified. , Seed proteins in Soybean comprise 2 major fractions that account for 70% to 80% of total protein composition: 11S and 7S globulins.
The following allergens have been characterised:
- Gly m 1, a 7-8 kDa protein, also known as HPS or Soybean hydrophobic protein. ,
- Gly m 2, an 8 kDa protein.7,
- Gly m 3, a 12-15 kDa protein, a profilin.4
- Gly m 4, a Bet v 1 homologue.7,
- Gly m 5, a vicilin-like protein, also known as vicilin or alpha subunit of beta-conglycinin.1, 2, 7
- Gly m 6, an 11S globulin (legumin-like protein), also known as legumin and Gly m Glycinin G1, Gly m Glycinin G2, Gly m Glycinin G4.1, 7,
- Gly m 2S albumin.
- Gly m 39kD.9
- Gly m Bd28K.
- Gly m Bd30K, a 30-34 kDa protein, a thiol protease of the papain family, also known as P34.
- Gly m Lectin.
- Gly m Bd 60K.
- Gly m Oleosin.
- Gly m Trypsin Inhibitor.
- Gly m IFR, an isoflavone reductase.
Gly m 6 is a legumin-like protein, also known as legumin or G subunit of glycinin. Unlike Gly m 1 and Gly m 2, major allergens to which subjects are exposed through inhalation of Soybean dust, the exposure route to the Gly m 6 allergen is Soybean ingestion.7
Legumins are seed-storage globulins that are the major components of plant seeds, including Broad bean or Fava bean, and constitute important protein sources for the human diet. Also known as 11S globulins, these proteins are quantitatively important seed-storage proteins. The 11S globulins are classified as part of the Cupin superfamily, and are large (300-450 kDa), generally hexameric, nonglycosylated members of a complex family of proteins, in which individual subunits are found both as intact precursor proteins (50-60 kDa) and composed of 2 polypeptide chains of different molecular masses and amino acid sequences (the heterodimeric form, composed of a 20- to 40-kDa chain plus a 20- to 25-kDa chain), linked together by one disulfide bridge.21, , The legumins are related to each other structurally, and are believed to share ancestors in common with vicilin-like 7S proteins.21
In addition to Gly m 6, several other legumins have been identified as food allergens, including Ana o 2 from Cashew nut, Ara h 3 and Ara h 4 from Peanut, the Soybean G1 and G2 glycinins, Cor a 9 from Hazelnut and possibly a legumin from Buckwheat.21
Sensitisation to the Soybean storage proteins Gly m 5 or Gly m 6 has been shown to be associated with severe reactions to Soybean. Therefore Gly m 5 or Gly m 6 could be considered diagnostic markers for identifying Soy-allergic subjects who are at high risk for severe clinical symptoms.1 However, in Birch tree-prevalent areas, primary sensitisation to Bet v 1 with potential clinical cross-reactivity to Soybean Gly m 4 may be frequent, especially in Soy products with a low level of processing; this factor needs to be taken into account when assessing the risk for severe Soybean-related allergic reactions, as Gly m 4 is able to cause severe allergic reactions to Soy in subjects with Birch pollen allergy.1, 5, 10
The potential benefit of evaluating Gly m 5 or Gly m 6 was demonstrated in a clinical study of 25 European adults and 5 children with confirmed Soybean allergy, where no correlation could be demonstrated between the dose of Soybean and the severity of symptoms, nor between the pattern of IgE reactivity (which was highly individual) and the severity of symptoms. However, of the group, 7 (23%) had severe Soy-related allergic reactions, and of these, 6 who experienced anaphylaxis (either by history, or during Soybean challenge) were sensitized to Gly m 5 or Gly m 6.1 The study also reported that the major Soybean storage proteins are putative major soybean allergens in children: in the 5 children with Soy allergy, a high frequency (>50%) of IgE-binding to Gly m 6, and especially to Gly m 5, was found.
Compiled by Dr Harris Steinman, developer of Allergy Advisor, http://allergyadvisor.com
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- Karamloo F, Wangorsch A, Kasahara H, Davin LB, Haustein D, Lewis NG, Vieths S. Phenylcoumaran benzylic ether and isoflavonoid reductases are a new class of cross-reactive allergens in birch pollen, fruits and vegetables. Eur J Biochem 2001;268(20):5310-20.
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