Ubiquitin-conjugating enzyme E2 A, RAD6 homolog A, HR6A, hHR6A, Ubiquitin carrier protein A, Ubiquitin-protein ligase A, UBE2A, RAD6A
Accepts ubiquitin from the E1 complex and catalyzes its covalent attachment to other proteins. In association with the E3 enzyme BRE1 (RNF20 and/or RNF40), it plays a role in transcription regulation by catalyzing the monoubiquitination of histone H2B at Lys-120 to form H2BK120ub1. H2BK120ub1 gives a specific tag for epigenetic transcriptional activation, elongation by RNA polymerase II, telomeric silencing, and is also a prerequisite for H3K4me and H3K79me formation. In vitro catalyzes Lys-11, as well as Lys-48-linked polyubiquitination. Required for postreplication repair of UV-damaged DNA.