The addition of chemical tags to proteins has long been recognized as one important mech￾anism to regulate different functions of the target protein. Of particular interest is the
enzymatic addition of one acetyl group to proteins, a reversible process that has been dis￾covered more than 40 years ago, and which can occur co- and posttranslationally. Highly
speci fi c acetyltransferases catalyze the addition of an acetyl group to target sequences in
proteins, and deacetylases speci fi cally remove these chemical tags if necessary.