protein_function: Promotes apoptosis by activating caspases in thecytochrome c,Apaf-1,caspase-9 pathway. Acts by opposing theinhibitory activity of inhibitor of apoptosis proteins (IAP).Inhibits the activity of BIRC6,bruce by inhibiting its binding tocaspases. Isoform 3 attenuates the stability and apoptosis-inhibiting activity of XIAP,BIRC4 by promoting XIAP,BIRC4ubiquitination and degradation through the ubiquitin-proteasomepathway. Isoform 3 also disrupts XIAP,BIRC4 interacting withprocessed caspase-9 and promotes caspase-3 activation. Isoform 1is defective in the capacity to down-regulate the XIAP,BIRC4abundance..
Diablo homolog, mitochondrial, also known as second mitochondria-derived activator of caspases(SMAC), is a protein that in humans is encoded by the DIABLO gene(direct IAP binding protein with low pI). It is mapped to 12q24.31. DIABLO can bind mammalian IAP homolog A(MIHA, or API3) and can also interact with MIHB, MIHC, and OpIAP, the baculoviral IAP. This gene encodes an inhibitor of apoptosis protein(IAP)-binding protein. The encoded mitochondrial protein enters the cytosol when cells undergo apoptosis, and allows activation of caspases by binding to inhibitor of apoptosis proteins. Over expression of the encoded protein sensitizes tumor cells to apoptosis. A mutation in this gene is associated with young-adult onset of nonsyndromic deafness-64.
