RNA-editing enzyme. Molecular model of a left-handed, RNA double helix (Z-RNA, centre) bound by the Z alpha domain of the human RNA-editing enzyme ADAR1 (double-stranded RNA adenosine deaminase, orange and blue). ADAR1 de-stabilises double stranded RNA (ribonucleic acid) by converting adenosine to inosine in the genetic sequence. ADAR1 is needed for the breakdown of adenosine from food and for the turnover of nucleic acids (RNA and DNA) in tissues.