There is currently little evidence that, beyond HRD1 and MARCH6 (the human Doa10 homologue), any of these additional ligases partner with UBE2J2 to catalyze non-lysine ubiquitylation under normal conditions, but it has been speculated that during cytomegalovirus infection the ligase TMEM129, which uses UBE2J2 as its cognate E2 partner, is appropriated by the viral protein US11 to degrade MHC-1 HC via oxyester-linked ubiquitylation (van den Boomen et al., 2014; McClellan et al., 2019). Here, UBE2J2 is linked to cytomegalovirus infection.