A schematic drawing showing the genomic organization of the first exons and promoter regions for the AdK-L and AdK-S genes in the human genome. The AdK gene (both AdK-L and AdK-S isoforms) in human is comprised of 11 exons. Except for the first exons, all the remaining exons (not shown here) are common to these isoforms. The Exon-1 and promoter region for the AdK-L isoform were identified in earlier work [32, 36]. The intron-1 for the AdK-L is now shown to contain the first exon for the AdK-S isoform. The first exons for the AdK-L and AdK-S isoforms encode for all the amino acids that distinguish these two isoforms. The upstream regions of both exons contain binding sites for several transcriptional factors, only some of which are shown here. The introns and exons are not drawn to the scale in this diagram.