E3 ubiquitin-protein ligase that mediates ubiquitination of PIK3C2B and inhibits its activity; mediates the formation of 'Lys-48'-linked polyubiquitin chains; the function inhibits CD4 T-cell activation. Acts as a regulator of retrograde transport: together with MAGEL2, mediates the formation of 'Lys-63'-linked polyubiquitin chains at 'Lys-220' of WASHC1, leading to promote endosomal F-actin assembly. Has a transcriptional repressor activity. Induces apoptosis by activating Jun N-terminal kinase and p38 kinase and also increases caspase-3-like activity independently of mitochondrial events. May function in male germ cell development. Has DNA-binding activity and preferentially bound to double-stranded DNA. 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. Homomultimerizes. Interacts with PML, EIF3S6, EPC1, CHD4 and EID1. Interacts with MAGED4, MAGEF1 and MAGEL2. Nuclear or cytoplasmic depending on the cell type. Recruited to retromer-containing endosomes via interaction with MAGEL2 (By similarity). Colocalized with PML and EIF3S6 in nuclear bodies. Expressed strongly in testis. Low levels were detected in spleen, thymus, cerebrum and cerebellum. The coiled-coil region mediates interaction with EPC1 and CHD4. The B box and coiled-coil domains mediate interaction with PML. The B box and the distal coiled-coil domains mediate homomultimerisation. The B30.2 domain mediates interaction with EIF3S6. Belongs to the TRIM/RBCC family.