Zeins are major seed storage proteins. Expressed in developing endosperm. Maximum expression between 18 and 28 days after pollination. The alpha zeins of 19 kDa and 22 kDa account for 70% of the total zein fraction. They are encoded by a large multigene family. Structurally, 22K and 19K zeins are composed of nine adjacent, topologically antiparallel helices clustered within a distorted cylinder. Not expressed in opaque-2 mutants. The floury-2 (fl2) mutation is associated with the synthesis of a novel 24 kDa alpha-zein storage protein and an altered protein body morphology (AC Q41896). The 24 kDa protein is expressed as a 22 kDa alpha-zein 16 with an uncleaved signal peptide, resulting in an enhanced lysine content of the grain and a soft texture of the endosperm. Belongs to the zein family.