Structure of wheat gamma-gliadin genes.

We have cloned and sequenced two linked members of the wheat (Triticum aestivum) gliadin multigene family. One gene encodes a gamma-gliadin which is 292 amino acids (aa) long. S1 mapping indicates that this gene is transcriptionally active. The second gene, which is only marginally active by S1 mapping, is closely related to the first gene. Moreover, it is probably incapable of encoding a full-length gamma-gliadin due to the presence of two premature in-frame stop codons. Neither gene contains introns. Nucleotide sequences of the two genes show the presence of characteristic repeats which have a derived aa consensus sequence Pro-Gln-Gln-Pro-Gln-Gln-Pro-Phe-Pro-Gln. A comparison of the promoter regions of these gamma-gliadin genes with those of the alpha-gliadin genes shows the presence of a highly conserved region that could be involved in tissue specific and developmental regulation.