SIVA plays an important role in the apoptotic pathway induced by the CD27 antigen, a member of the tumor necrosis factor receptor (TFNR) superfamily. SIVA is a small cysteine-rich protein with a unique N-terminal amphipathic helical region, a death domain homology region (DDHR) and a C-terminal cysteine-rich B-box-like or zinc-finger-like structure. The DDHR domain binds to CD27 and induces apoptosis in T cells through a caspase-dependent mitochondrial pathway. SIVA inhibits BCL2L1 isoform Bcl-xL anti-apoptotic activity and inhibits activation of NFk-B and promotes T-cell receptor-mediated apoptosis. SIVA represents a potential therapeutic target for the treatment of neuronal cell death diseases.Synonyms: Apoptosis regulatory protein Siva, CD27-binding protein, CD27BP