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. 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. Self-associates. Interacts with SP1 in an oxidative stress-regulated manner. Interacts with SIGMAR1 in an oxidative stress-regulated manner. Interacts with ZBTB16 (via C2H2-type zinc finger domains 1 and 2). Predominantly in the nucleus, but some amounts were also found in the cytoplasm. Oxidative stress stimulates its shuttling from the cytoplasm into the nucleus. Recruited to nuclear bodies via its interaction with ZBTB16. Localizes to the cell soma and neuritis and only slightly to the nucleus in the neurons of most brain areas. Predominantly expressed in brain. Auto-ubiquitinated. Belongs to the TRAFAC class dynamin-like GTPase superfamily. GB1/RHD3 GTPase family. GB1 subfamily.