Zein, the major storage protein of maize endosperm, is constituted by a group of similar polypeptides encoded by a multigene family. The structural genes are located into three main clusters on chromosomes 4, 7 and 10. The rate of accumulation of zein polypeptides is under the control of several positive regulatory loci. The mutant alleles at these loci (
O2, O6, O7, F12, De-B30, Mc
) reduce more or less drastically the rate of zein deposition. By analysing the interactions among the mutants, epistatic, additive and synergistic effects were observed indicating the existence of multiple pathways controlling zein deposition. Proteins, other than zeins, associated with the
O2, O6
and
F12
loci have been identified and characterized.
