Sulfur-rich seed storage protein that remains undegraded at germination. Two-subunit monomeric unit made of alpha and beta subunits coupled by disulfide bonds (at pH 4.5 and under non-reducing conditions) (By similarity). Monomeric alpha and beta subunits in reducing conditions (By similarity). Can also form oligomers including dimer, tetramer and cyclic hexamer (trimer of dimers) (at pH > 5.5) (By similarity). Component of globulins complexes which accumulate in seeds (By similarity). Interacts with flavonoids (e.g. apigenin glucosides) present in globulins complexes (By similarity). Present in the extracellular spaces of germinating seedlings. Causes an allergic reaction in human (PubMed:12065909). Binds to IgE (PubMed:12065909). Belongs to the peptidase A1 family.