Exonuclease, RNase T/DNA polymerase III This entry includes a variety of exonuclease proteins, such as ribonuclease T [<cite idref="PUB00004421"/>] and the epsilon subunit of DNA polymerase III. Ribonuclease T is responsible for the end-turnover of tRNA,and removes the terminal AMP residue from uncharged tRNA. DNA polymerase III is a complex, multichain enzyme responsible for most of the replicative synthesis in bacteria, and also exhibits 3' to 5' exonuclease activity.