<p><b>Copyright information:</b></p><p>Taken from "Adaptive evolution of multiple-variable exons and structural diversity of drug-metabolizing enzymes"</p><p>http://www.biomedcentral.com/1471-2148/7/69</p><p>BMC Evolutionary Biology 2007;7():69-69.</p><p>Published online 2 May 2007</p><p>PMCID:PMC1885805.</p><p></p> Each cluster contains multiple variable first exons arrayed in tandem and a common set of 4 downstream constant exons. These exons are indicated by vertical colored bars: (green) phenol-group variable exons; (orange) bilirubin-group variable exons; (blue) zebrafish variable exons; (gray) pseudogene (ψ) or relic (r); and (red) constant exons. The approximate length of each cluster is shown below the corresponding panels
