Involved in RNA editing. Catalyzes the specific deamination of adenosine-34 in several cytosolic tRNA species. Generates inosine at the wobble position of the anticodon loop. adenosine(34) in tRNA + H(+) + H2O = inosine(34) in tRNA + NH4(+) Interacts with TAD2. Localizes predominantly to the nucleus. Embryonic lethality due to embryo development arrest at the globular stage. Belongs to the cytidine and deoxycytidylate deaminase family. ADAT3 subfamily.