E3 ubiquitin-protein ligase involved in the positive regulation of abscisic acid (ABA) signaling and responses to salt and osmotic stresses during seed germination and early seedling development. Acts additively with RHA2A in regulating ABA signaling and drought response. 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. Interacts with NAC19. Expressed in vascular tissue, root tips, embryos and pistils. By the proteasome inhibitor MG132. Down-regulated during reinitiation of mitotic activity. The ring domain is sufficient for the interaction with NAC19. No visible phenotype.