Possesses E3 ubiquitin-protein ligase activity in vitro when associated with the E2 enzyme UBC8 in vitro (PubMed:21969385, PubMed:28626006). Plays combinatory roles with AIRP1 in the positive regulation of the abscisic acid-mediated drought stress response (PubMed:21969385). Plays a positive role in abscisic acid- and high salinity-regulated seed germination through the ubiquitin-proteasome-dependent down-regulation of ATP1/SDIRIP1 (PubMed:28626006). 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. Expressed in germinating seeds, flower organs and siliques. Induced by salt stress, cold stress, drought stress and abscisic acid (ABA). The RING-type zinc finger domain is required for E3 ligase activity. No visible phenotype under normal growth conditions, but mutant seeds are insensitive to germination inhibition by abscisic acid (ABA). Plants over-expressing AIRP2 exhibit tolerance to severe drought stress.