Members of this family such as UL21a found in Human cytomegalovirus (HCMV) is required for HCMV to establish efficient productive infection. It is a short-lived cytoplasmic protein that facilitates HCMV replication. It has also been shown to be responsible for APC1, APC4 and APC5 degradation.
Jiyao W et al.(2023). "The conserved domain database in 2023.",