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. Accumulates in seeds 8 days after anthesis. First observed in siliques 15 days post anthesis and accumulates progressively as native isoforms or proteolytic fragments during the last week of seed maturation/desiccation. Present in dry seeds, but disappears during their germination (at protein level). Ubiquitinated. Proteolytically processed during seed maturation at a conserved Asn-Gly peptide bond by an asparaginyl endopeptidase to produce two mature polypeptides referred to as alpha and beta subunits that are joined together by a disulfide bond. Phosphorylated in seeds on some Tyr residues in response to abscisic acid (ABA). Belongs to the 11S seed storage protein (globulins) family.