E3 ubiquitin-protein ligase that acts as a negative regulator of abscisic acid (ABA) signaling. Mediates ubiquitination and subsequent proteasomal degradation of the transcription factor ABI3. 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 ABI3 (via C-terminus). Highly expressed in leaves and at lower levels in flowers and seeds. Auto-ubiquitinated. Hypersensitivity to abscisic acid (ABA).