Bak BH3 corresponds to amino acids 72 - 87 in the BH3 region of human Bak and is the miminal sequence for binding to Bcl-xL (B-cell lymphoma-extra large), a transmembrane molecule in the mitochondria which is a member of the Bcl-2 family and key regulator of apoptosis. Bak BH3 has high affinity binding to a surface pocket of the Bcl-XL protein that is essential for its death antagonist function. Bcl-2 is a potent suppressor of apoptosis, and its overexpression contributes to tumourigenesis in many types of human cancers.
