Mutants for the 57H character have high level of 57 kD and low level of 40kDa and 20kDa polypeptides of rice storage proteins. Glutelin, a major storage protein in starchy endosperm in rice, is synthesized as a 57 kDa precursor polypeptide and cleaved into two subunits of glutelin alpha (40 kDa) and beta (20 kDa) by post-translational modification.