Retention of plasmid DNA in mammalian cells is enhanced by binding of the Epstein-Barr virus replication protein EBNA1.

The capacity to bind the Epstein-Barr viral protein EBNA1 increases the retention of the plasmid in dividing cells. This retention requires binding of multiple EBNA1 molecules for function, although significant retention activity is seen with fewer EBNA1 binding sites than are required to activate replication or transcription. The regions of EBNA1 that are required for increased plasmid retention overlap with those required for activation of transcription and replication. The similarities in traits of EBNA1 that are required for support of DNA replication and retention of plasmid DNA indicate that both may be mediated by interactions with an overlapping set of cellular proteins.