EDD, the ER ubiquitin ligase from the HECT ligases, contains an N-terminal ubiquitin-associated domain which binds ubiquitin. Ubiquitin is recognised by helices alpha-1 and -3 in in the UBA domain. EDD is involved in DNA damage repair pathways and binds to mono-ubiquitinated proteins.
Jiyao W et al.(2023). "The conserved domain database in 2023.",