The emergence of specific ARID subfamilies appears to have occurred early in evolution. S.cerevisieae encodes two ARID proteins. The ARID sequences do not correlate closely with any particular human subfamily, but overall the proteins seem most similar to the ARID1 and JARID1 subfamilies. Schizosaccharomyces pombe encodes four ARID proteins, two that are members of chromatin remodeling complexes and two that share similarity to the JARID1 subfamily. Ceanorhabditis elegans encodes four ARID proteins, aligning with human subfamilies ARID1, ARID2, ARID3 and JARID1, thus including a single AT-specific subfamily representative (for an excellent review of ARID evolution see ). The ARID protein CFI-1 is the only identified member of an ARID3-type subfamily within C.elegans and prefers the same AT-rich consensus sequence as Dri in a competition assay (37). Drosophila melanogaster encodes six ARID proteins, one aligning with each subfamily except the second AT-rich specific subfamily ARID5. These patterns suggest that ARIDs probably began as sequence non-specific and gained the property of sequence specificity through evolution.
