Seed storage protein. Hexamer; each subunit is composed of an acidic and a basic chain derived from a single precursor and linked by a disulfide bond. Expressed only in immature seeds. Expressed between 7 and 28 days after pollination. The sequence of the probable beta chain is highly homologous to the N-terminal sequence of BW24KD, a major buckwheat allergen. Belongs to the 11S seed storage protein (globulins) family.