Amino acid sequence data from vicilin of pea (Pisum sativum L.) were compared with predicted sequences from complementary DNA species. The sites of potential post-translational proteolytic cleavage of vicilin precursor polypeptides were located in polar regions of the polypeptide, at acidic or amide residues. Proteolysis did not take place in precursors containing a functionally distinct sequence: neutral residue-hydrophobic residue-basic residue at the cleavage site. Differences between the genomic sequences encoding vicilin thus specify proteolytic cleavage of vicilin precursor polypeptides.