Inhibitor of apoptosis domain
The inhibitor of apoptosis domain -- also known as IAP repeat, Baculovirus Inhibitor of apoptosis protein Repeat, or BIR -- is a structural motif found in proteins with roles in apoptosis, cytokine production, and chromosome segregation. Proteins containing BIR are known as inhibitor of apoptosis proteins, or BIR-containing proteins, and include BIRC1, BIRC2, BIRC3, BIRC4, BIRC5 and BIRC6.
BIR domains belong to the zinc-finger domain family and characteristically have a number of invariant amino acid residues, including 3 conserved cysteines and one conserved histidine, which coordinate a zinc ion. They are typically composed of 4-5 alpha helices and a three-stranded beta sheet.
