Exhibits weak E3 ubiquitin-protein ligase activity ( ). E3 ubiquitin ligases accept ubiquitin from an E2 ubiquitin-conjugating enzyme in the form of a thioester and then directly transfer the ubiquitin to targeted substrates ( ). Can ubiquitinate AKT1 preferentially at 'Lys-284' involving 'Lys-48'-linked polyubiquitination and seems to be involved in regulation of Akt signaling by targeting phosphorylated Akt to proteasomal degradation . Mediates polyubiquitination of cytoplasmic TP53 at 'Lys-24' which targets TP53 for proteasomal degradation, thus reducing TP53 levels in the cytoplasm and mitochondrion . Proposed to preferentially act as a SUMO E3 ligase at physiological concentrations . Plays a role in the control of mitochondrial morphology by promoting mitochondrial fragmentation, and influences mitochondrial localization ( ). Likely to promote mitochondrial fission through negatively regulating the mitochondrial fusion proteins MFN1 and MFN2, acting in a pathway that is parallel to the PRKN/PINK1 regulatory pathway . May also be involved in the sumoylation of the membrane fission protein DNM1L (, ). Inhibits cell growth (, ). When overexpressed, activates JNK through MAP3K7/TAK1 and induces caspase-dependent apoptosis . Involved in the modulation of innate immune defense against viruses by inhibiting RIGI-dependent antiviral response . Can mediate RIGI sumoylation and disrupt its polyubiquitination .
Subcellular locations: Mitochondrion outer membrane, Peroxisome
Transported in mitochondrion-derived vesicles from the mitochondrion to the peroxisome.
Widely expressed with highest levels in the heart, skeletal muscle, placenta, kidney and liver. Barely detectable in colon and thymus.