E3 ubiquitin-protein ligase which ubiquitinates itself in cooperation with an E2 enzyme UBE2D2/UBC4 and serves as a targeting signal for proteasomal degradation. May play a role in regulation of neuronal functions. May act as a regulator of synaptic vesicle exocytosis by controlling the availability of SNAP25 for the SNARE complex formation. 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 SNAP25. Enriched at synaptic terminals where it exists in a soluble form and a synaptic vesicle-associated form. Associated with the cytoskeleton (By similarity). Found in proximal dendrites of pyramidal neurons in the cerebral cortex and hippocampus, and Purkinje cells in the cerebellum (PubMed:20085810). Brain. Expression is higher in the cerebral cortex and hippocampus (at protein level). Its expression is mainly confined to the central nervous system. The developing neocortex, the dorsal thalamus, the midbrain, the basal area of the hindbrain and spinal cord show high level of expression during embryogenesis. In adult brain, it is detected in the Purkinje cells of the cerebellum, in the hippocampus, and in the cortex. First seen at 9.5 dpc. From 9.5 dpc to 11.5 dpc, it remains uniformly present in the ventral part of the entire neuroepithelium and in the dorsal root ganglia. A more restricted central nervous system (CNS) expression is observed at 13.5 dpc and 15.5 dpc when it is present in specific regions of the forebrain, midbrain, hindbrain and spinal cord. The coiled coil domain mediates the interaction with the N-terminal t-SNARE domain of SNAP25. Auto-ubiquitinated. May be due to an intron retention. May be due to a competing acceptor splice site and to an exon skipping. May be due to a competing donor splice site and ?. May be due to an intron retention. May be due to exon skipping. May be due to an exon inclusion. Belongs to the TRIM/RBCC family.