Major seed storage protein. Homotrimer. Cotyledonary membrane-bound vacuolar protein bodies. N-glycosylated; glycans consist in Man9(GlcNAc)2 and Man7(GlcNAc)2 when dually glycosylated at Asn-258 and Asn-347, whereas it consists in Xyl-Man3(GlcNAc)2 when solely glycosylated at Asn-258. Belongs to the 7S seed storage protein family.