E3 ubiquitin ligase that ubiquitinates apbb1 for its degradation by the proteasome and thus prevents apoptosis and promotes survival of neurons (By similarity). Has a dual role in neurons as it is also required for dendrite growth and maintenance for which its ligase activity is not critical (By similarity). May act as a scaffold molecule to regulate this process (By similarity). Acts as a downstream effector of the interconnected PI3K and MAPK signaling pathways and thus participates in the regulation of the cell cycle (By similarity). 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.