E3 ubiquitin-protein ligase that plays an important role in neuronal differentiation, including neurogenesis and gliogenesis, during brain development. During embryonic development initiates neuronal differentiation by inducing cell cycle arrest at the G0/G1 phase through up-regulation of cell-cycle regulatory proteins . Plays a role not only in the fetal period during the development of the nervous system, but also in the adult brain, where it is involved in the maintenance of neural functions and protection of the nervous tissue cells from oxidative stress-induced damage. Exhibits GTPase and E3 ubiquitin-protein ligase activities. Regulates dendritic spine density and synaptic neurotransmission; its ability to hydrolyze GTP is involved in the maintenance of dendritic spine density.