Trims short 3' overhangs of a variety of RNA species, leaving a one or two nucleotide 3' overhang. Responsible for the end-turnover of tRNA: specifically removes the terminal AMP residue from uncharged tRNA (tRNA-C-C-A). Also appears to be involved in tRNA biosynthesis. Binds two Mg(2+) per subunit. The active form of the enzyme binds two Mg(2+) ions in its active site. The first Mg(2+) forms only one salt bridge with the protein. Homodimer. Member of the DEDD group of RNAses that are characterized by the presence of four acidic residues in the active site. These residues are conserved even when the proteins have highly divergent sequences. Belongs to the RNase T family.