Active nuclear import and cytoplasmic retention of activation-induced deaminase

The enzyme activation-induced deaminase (AID) promotes antibody diversification after B-cell activation, by causing mutagenic lesions on DNA. Hence, AID's actions must be tightly controlled. AID is found mainly in the cytosolic compartment and contains a known nuclear export sequence. Now a structural nuclear localization sequence and a cytosolic-retention determinant are identified in AID and found to have a role in localization and function.