When complexed to BIRC5, interferes with apoptosome assembly, preventing recruitment of pro-caspase-9 to oligomerized APAF1, thereby selectively suppressing apoptosis initiated via the mitochondrial/cytochrome c pathway. Down-regulates hepatitis B virus (HBV) replication.
Specificity
Natural and recombinant Human Hepatitis B virus X-interacting protein
Homodimer (Probable). Interacts with phosphorylated BIRC5; the resulting complex binds pro-caspase-9, as well as active caspase-9, but much less efficiently. Interacts with SUPV3L1. Interacts with hepatitis B virus (HBV) oncoprotein HBX C-terminus.