Participates in the last steps of viral maturation and release. Associates with nuclear capsids prior to DNA encapsidation and later preserves the integrity of nucleocapsids through secondary envelopment at the assembly compartment. Interacts with host CCNA2 and thereby blocks the onset of lytic gene expression to promote establishment of a quiescent state of infection in undifferentiated cells. Interacts with host BICD1 and RAB6A. Interacts with small capsid protein UL48A; this interaction links together the capsid and pp150. Interacts with host CCNA2. Found initially localized in the host nucleus, associated either with the nuclear membrane or with viral assembly regions, and later in the host cytoplasm. Phosphorylated by host CCNA2. Belongs to the herpesviridae large structural phosphoprotein family.