Promotes efficient viral DNA replication. Recruits the DNA polymerase processivity factor to pre-replication foci. Isoforms p34, p43, p50 and p84 self-interact and interact with each other via a shared N-terminal region; these interactions play an important role in their intranuclear targeting and in 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 stages of viral infection (PubMed:16501081). Isoforms 1, 2, 3 and 4 share a common N-terminus. The isoforms p34, p43, p50 and p84 are cleaved by host calpain-1/CAPN1 and calpain-2/CAPN2 to generate p20, p26 and p28. Most abundant product which level of expression remains constant throughout infection. Belongs to the herpesviridae U79/UL112 family.