E3 ubiquitin-protein ligase involved in the regulation of organ and seed size. Acts synergistically with DA1 to regulate seed size. Functions synergistically with DA1 to restrict cell proliferation in the maternal integuments of ovules and developing seeds. Seems to function independently of BB. Possesses E3 ubiquitin-protein ligase activity in vitro (PubMed:24045020). Polyubiquitinates DA1, DAR1 and DAR2, but not DAR3 (PubMed:28167503). 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 DA1 (via C-terminus). Highly expressed during early stages of petal, stamen, carpel and ovule development, and expression decreases at the later stages of organ development. Increased organ size, biomass, and seed size and weight. 'Da' means 'large' in Chinese (PubMed:24045020). Plants overexpressing DA2 exhibit reduced organ size, biomass, and seed size and weight (PubMed:24045020).