E3 ubiquitin-protein ligase involved in the positive regulation of abscisic acid-dependent drought stress responses. Possesses E3 ubiquitin ligase activity in vitro. 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. Induced by abscisic acid (ABA), and drought and salt stresses. No visible phenotype under normal growth conditions, but mutant plants have decreased sensitivity to abscisic acid (ABA) and reduced tolerance to drought stress.