The ADAR family protein. (a) Domain architecture of metazoan ADARs. The deaminase domain is depicted in purple, while the dsRBMs are shown in orange and Z-DNA binding domains, unique to human ADAR1, are presented in green. The human genome contains three ADAR genes (hADAR1 to 3). That of the squid Loligo pealeii contains an ADAR2-like gene (sqADAR2) that produces variants (a and b) through alternative splicing. C. elegans contains two genes (ceADAR1 and 2), while the genome of D. melanogaster encodes only one (dADAR), an enzyme homologous to hADAR2. Although the dsRBMs found in the Hydra magnapapillata genome are highly divergent, five such motifs are recognizable in hmADAR, the only identified gene in this species. Human and Drosophila ADAT architectures are included (red), as these enzymes are believed to be ancestral to present-day ADARs. (b) Cladogram based on ADAR catalytic domain sequences. MacVector was used to generate a relatedness tree based on the protein sequences of ADAR catalytic domains from different species. C. elegans ADAR2 is absent due to difficulty aligning the catalytic domain. Note that human and Drosophila ADATs (red) cluster as the outgroup.
Savva et al. Genome Biology 2012 13:252 doi:10.1186/gb-2012-13-12-252