Has E2-dependent E3 ubiquitin-protein ligase activity. Ubiquitinates MAGED1 antigen leading to its subsequent degradation by proteasome. May be involved in protein sorting. 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. Binds ubiquitin-conjugating enzymes (E2s). Binds, in vitro and in vivo, the MAGE conserved domain of MAGED1. Binds weakly Necdin, in vitro. Interacts with UBE2D2. Alternative splicing appears to be tissue-specific. Expressed in brain, liver, kidney. Highest levels in brain where it is found in many regions including cortical and subcortical areas and in neurons of the amygdala. Weak expression also found in testis. Also expressed in developing embryo. By fear memory. Differential induction of isoforms. The RING-type zinc finger domain interacts with an ubiquitin-conjugating enzyme (E2) and facilitates ubiquitination. Substrate for E2-dependent ubiquitination.