<p>Exon structure, domain composition and the six basic forms of PDZ/LIM genes. (A) The exon composition of the human PDZ-LIM domain encoding genes in alphabetical order. Indicated are <i>ALP</i> (ENSG00000154553), <i>ZASP</i> (ENSG00000122367, Elfin (ENSG00000107438), ENIGMA (ENSG00000196923), <i>Enigma-Homolog</i> (ENH) (ENSG00000163110) <i>LIMK1</i> (ENSG00000106683, OTTHUMG00000023448), <i>LIMK2</i> (ENSG00000182541), <i>LMO7</i> (ENSG00000136153), <i>Mystique</i> (ENSG00000120913) and RIL (ENSG00000131435). Domains are color coded on the exons: LIM yellow, PDZ blue, CH red and ZM motif green, while transcription start sites are indicated after non coding regions (colored white) with a small arrow on top. (B) Presence of domain architectures for PDZ and LIM genes and their species distribution. Six basic gene structures can be found amongst the different taxons. The <i>tungus gene</i>, found in the two <i>arthropod species investigated and the nematode homolog Eat-1 both</i> encode one N-terminal PDZ and four C-terminal LIM domains. Eat-1 has been described earlier as the <i>Caenorhabditis elegans</i> ALP/Enigma gene <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0000189#pone.0000189-McKeown1" target="_blank">[50]</a>. Only a single <i>LIMK</i> gene was found per invertebrate species examined, and the <i>LMO7</i> homolog lacks the CH domain (<i>CG31534</i>). The LMO7 gene of <i>Drosophila</i> melanogaster lacks not only the CH domain but also the PDZ domain (not shown, see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0000189#pone.0000189.s002" target="_blank">Supplemental table S1</a>). As not all ALP and Enigma subfamily members share the ZM domain (ZASP and ALP contain 2 and Elfin one ZM motif) we have excluded the ZM motif from these groups and show only a ZM motif for eat-1/tungus in this figure.</p
