Claim: There are three members of the ADAR family, ADARs 1-3, with ADAR 1 and ADAR 2 being the only enzymatically active members and involved in editing at the Q/R site, and ADAR3 is thought to have a regulatory role in the brain and is restricted to the brain only.
Evidence: There are three members of the ADAR family ADARs 1-3 with ADAR1 and ADAR2 being the only enzymatically active members. Editing at A and B sites has been demonstrated to be due to ADAR1 editing. ADAR3 is thought to have a regulatory role in the brain. The double stranded regions of RNA are formed by base-pairing between residues in the close to region of the editing site with residues usually in a neighboring intron but can be an exonic sequence.