Deaminates adenosine-34 to inosine in many tRNAs. Heterodimer with TAD2. Present with 892 molecules/cell in log phase SD medium. Belongs to the cytidine and deoxycytidylate deaminase family. ADAT3 subfamily. In contrast to other cytidine and deoxycytidylate deaminase, lacks to conserved Glu active site in position 218 which is replaced by a Val residue, suggesting that it acts as a regulatory subunit.