InterPro domain: IPR002530

Alpha-prolamins are the major seed storage proteins of species of the grass tribe Andropogonea. They are unusually rich in glutamine, proline, alanine, and leucine residues and their sequences show a series of tandem repeats presumed to be the result of multiple intragenic duplication [ 1 ]. In Zea mays (Maize), the 22kDa and 19kDa zeins are encoded by a large multigene family and are the major seed storage proteins accounting for 70% of the total zein fraction. Structurally the 22kDa and 19kDa zeins are composed of nine adjacent, topologically antiparallel helices clustered within a distorted cylinder. The 22kDa alpha-zeins are encoded by 23 genes [ 2 ]; twenty-two of the members are found in a roughly tandem array forming a dense gene cluster. The expressed genes in the cluster are interspersed with nonexpressed genes. Interestingly, some of the expressed genes differ in their transcriptional regulation. Gene amplification appears to be in blocks of genes explaining the rapid and compact expansion of the cluster during the evolution of maize.

1. Studies of the zein-like alpha-prolamins based on an analysis of amino acid sequences: implications for their evolution and three-dimensional structure. Proteins 15, 88-99
2. Sequence, regulation, and evolution of the maize 22-kD alpha zein gene family. Genome Res. 11, 1817-25