UBE3A (also known as E6-AP) is an E3 ubiquitin-protein ligase which accepts ubiquitin from an E2 ubiquitin-conjugating enzyme in the form of a thioester and transfers it to its substrates. It regulates cell proliferation by promoting proteasomal degradation of p27 []. It can also serve as a molecular circadian clock through regulating the BMAL1 transcription factor [].
