A nucleotide sequence is provided for expression of a heterologous protein of interest that is localized to the endoplasmic reticulum protein bodies in transgenic plants, plant cells, and seeds. Said nucleotide sequence comprises a promoter, the 5' untranslated region from the maize .gamma.-zein gene, the .gamma.-zein signal peptide sequence, a sequence encoding a heterologous protein of interest, and the 3' untranslated region from the maize .gamma.-zein gene, operatively linked.