Functions as an E3 ubiquitin ligase (By similarity). May be involved in the abscisic acid-mediated signaling pathway, at least during germination. 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. Binds to SD11, SD16, SD17, SD18, SD113, SD129 and SD25. Relocates from nucleus to plasma membrane when phosphorylated. A number of isoforms are produced. According to EST sequences. Phosphorylated by SD1-6 and SD1-7. Reduced abscisic acid (ABA) sensitivity during seed germination.