Needed for efficient replication. Recruits the DNA polymerase processivity factor to pre-replication foci. Isoforms 1, 2, 3 and 4 interacts with themselves and with each other via their shared N-terminal regions; these interactions are important to both their intranuclear targeting and the recruitment of UL44 to subnuclear sites for viral replication. Found in subnuclear structures known as promyelocytic leukemia oncogenic domains (PODs) or nuclear domain 10 (ND10) during the early. Isoforms 1, 2, 3 and 4 share a common N-terminus. Most abundant product which level of expression remains constant throughout infection. Belongs to the herpesviridae U79/UL112 family.