Schematic representation of the intron-exon structures of the wheat PDI and PDI-like genes. Only the ORF sequences have been reported, whereas the 5' and 3' UTRs have been omitted. Exons are indicated by yellow boxes, introns by black boxes, numbers represent their length (bp). Tetrapeptide sequence and position of the thioredoxin-like catalytic sites are indicated as well as the C-terminal tetrapeptide. Exons encoding each identified domain are labelled by braces.