The anatomy of human, mouse, zebrafish and chicken RGMa genes is shown. Exons are indicated by boxes, with coding regions in blue and non-coding regions in yellow. The assignment of exon numbers is based on comparison with mouse RGMa. The polyadenylation site, when known, is depicted by a vertical arrow. The location of zebrafish exon 1 is based on mapping available EST (expressed sequence tag) data taken from GenBank® (accession numbers AL911518 and EH589480). The length of one of the introns of chicken RGMa is not known (shown as two angled lines), as the putative exon 2 cannot be mapped to the genomic DNA sequence, which appears to be incomplete in this region. Chicken exon assignments are in parentheses because the putative exon 1 cannot be mapped to the genome.