Genomic structure and organization of a prototypical avian preproghrelin gene (based on the chicken gene). The gene exhibits five exons (four coding exons shown in black) and four introns with the positions of the proximal promoter (PR) and the start (ATG) and stop (TGA) codons indicated. The portions of the preproghrelin precursor protein encoded by each exon are indicated in boxes. Also indicated are two sequence features detected in different avian genes. These include an 8 bp insertion/deletion (INDEL) located in exon 1 and exon extensions ( and ) of exons 1 and 2 detected only in the turkey.
