Deaminates adenosine-34 to inosine in many tRNAs. adenosine(34) in tRNA + H(+) + H2O = inosine(34) in tRNA + NH4(+) Heterodimer with TAD3. Present with 830 molecules/cell in log phase SD medium. Belongs to the cytidine and deoxycytidylate deaminase family. ADAT2 subfamily.