A Viral Protein Antagonist for Both AID and APOBEC3

The APOBEC family of cytidine deaminases is part of the innate immune response to infections by multiple RNA- and DNA-containing viruses. Since the activity of these enzymes, typically APOBEC3, often involves mutations that inhibit or block viral replication, viruses have evolved antagonists that limit APOBEC function. The retrovirus mouse mammary tumor virus (MMTV) encodes an APOBEC antagonist, Rem. Surprisingly, Rem appears to inhibit APOBEC3 through proteasomal degradation of a different APOBEC enzyme, AID.