E3 ubiquitin-protein ligase which accepts ubiquitin from specific E2 ubiquitin-conjugating enzymes, and transfers it to substrates, generally promoting their degradation by the proteasome. S-ubiquitinyl-[E2 ubiquitin-conjugating enzyme]-L-cysteine + [acceptor protein]-L-lysine = [E2 ubiquitin-conjugating enzyme]-L-cysteine + N(6)-ubiquitinyl-[acceptor protein]-L-lysine. Protein modification; protein ubiquitination. Interacts with UBE2C/UbcH10 (E2 ubiquitin-conjugating enzyme). In vitro, interacts with cyclin-B. The C-terminal half (AA 188-389) is able to bind cyclin-B and shows a self-ubiquitination activity (mono-, poly, or multi-ubiquitination) in a HECT-like sequence dependent manner. Ubiquitinated by UBCH10 (E2 ubiquitin-conjugating enzyme).