E3 ubiquitin-protein ligase that acts as a positive regulator of abscisic acid-related stress signal transduction (PubMed:17573536, PubMed:18685183). Interacts with and ubiquitinates ATP1/SDIRIP1 to modulate ATP1/SDIRIP1 stability through the 26S proteasome pathway. Regulates abscisic acid (ABA) and salt stress responses by negatively affecting ATP1/SDIRIP1 stability. The SDIR1-ATP1/SDIRIP1 complex plays an important role in ABA signaling through the ubiquitination pathway (PubMed:25616872). 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. Interacts with ATP1/SDIRIP1. Ubiquitous. Expressed at all developmental stages. Up-regulated by salt and drought stress, but not by abscisic acid. The up-regulation is stronger and earlier when the roots are colonized by the endophytic fungus P.indica. The RING-type zinc finger domain is required for E3 ligase activity. Longer primary root and NaCl and ABA insensitivity.