Serine/threonine protein kinase that plays important roles in several processes including viral morphogenesis, nuclear viral egress, viral replication or regulation of host cell cycle progression (PubMed:17910700, PubMed:32973148). Participates in the acquisition of tegument during virion morphogenesis in the nucleus (By similarity). Phosphorylates host SAMHD1 and thereby counteracts its antiviral effect by reducing its dNTP hydrolase activity (PubMed:31548683). Inhibits host DNA synthesis by cyclin A/CDKN2A sequestration to the cytoplasm (PubMed:32973148). ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Interacts with host CCNA2; this interaction sequesters CCNA2 to the cytoplasm. Present in host nucleus at early times but redistributes to a predominantly cytoplasmic localization pattern at 24 hours post infection. Deletion mutants show a loss of typical nucleocapsid clustering in host-infected nuclei. Belongs to the protein kinase superfamily. Tyr protein kinase family. HCMV ganciclovir subfamily.