Promotes apoptosis by activating caspases in the cytochrome c/Apaf-1/caspase-9 pathway. Acts by opposing the inhibitory activity of inhibitor of apoptosis proteins (IAP). Inhibits the activity of BIRC6/bruce by inhibiting its binding to caspases.
Attenuates the stability and apoptosis-inhibiting activity of XIAP/BIRC4 by promoting XIAP/BIRC4 ubiquitination and degradation through the ubiquitin-proteasome pathway. Also disrupts XIAP/BIRC4 interacting with processed caspase-9 and promotes caspase-3 activation.
Defective in the capacity to down-regulate the XIAP/BIRC4 abundance.
Subcellular locations: Mitochondrion, Cytoplasm, Cytosol
Released into the cytosol in a PARL-dependent manner when cells undergo apoptosis.
Ubiquitously expressed with highest expression in testis. Expression is also high in heart, liver, kidney, spleen, prostate and ovary. Low in brain, lung, thymus and peripheral blood leukocytes. Isoform 3 is ubiquitously expressed.