Rice storage proteins have high content of 10-kDa and 16-kDa polypeptide and low content of 13b polypeptide. Rice storage proteins accumulate as two types of protein bodies in the starchy endosperm. Rice prolamine is stored in protein body type I (PB-I, spherical proteinaceous particles of lamellar structure). Rice glutelin is deposited in protein body type II (PB-II, a uniformly electron dense structure, 2-3 micron diameter). In SDS-PAGE analysis, PB-I has 10-kDa, 13a (a larger component of 13 kDa), 13b (a smaller component of 13 kDa) and 16-kDa polypeptides; and polypeptides of PB-II are 22-23 kDa, 26 kDa and 37-39 kDa. The dominant gene Esp4 appeared to be inherited maternally.