Figure 3.

Unique role for Cela1 in the placental mammalian lineage. (A) Cela1 protein sequences were analyzed with clustering of mammalian Cela1 protein sequences away from mammalian Cela2 and Cela3 and nonmammalian Cela1, Cela2, and Cela3. Common names are listed. Different vertebrate classes are color coded, and sequences for Cela1, Cela2, and Cela3 are coded in black, gray, and white, respectively. Only two mammalian Cela1 protein sequences failed to cluster with the other mammalian Cela1 sequences: the platypus and the Tasmanian devil (red arrows). The rabbit Cela1 protein sequence was likely incorrect because it included introns in its protein sequence, but it was retained for completeness (blue arrow). (B) Phylogenetic tree of Ensembl 200-bp promoter sequences for all Cela family members. Like the pattern observed with protein sequences, mammalian Cela2 and Cela3 promoter sequences were similar to nonmammalian Cela1, Cela2, and Cela3 sequences, but mammalian Cela1 sequences were less similar. Again, the Tasmanian devil and platypus Cela1 sequences failed to cluster with other mammalian Cela1 sequences. (C) Using the Ensembl and Entrez Gene databases, the absence or presence of the Cela1 gene (green or red, respectively) or the presence of zero, one, or two Cela2 and Cela3 genes (red, yellow, and green, respectively) were plotted in a simplified heat map. Annotated mammals were segregated by diet, and nonplacental mammals are highlighted in blue. Except for the opossum, all annotated mammals had retention of the Cela1 gene, whereas herbivores had more frequent loss of Cela2 and Cela3 homologs. Primates had higher retention of both Cela2 and Cela3 homologs.