RT Journal Article SR Electronic T1 Vitamin K2 Covalently Binds to Bak and Induces Bak-Mediated Apoptosis JF Molecular Pharmacology JO Mol Pharmacol FD American Society for Pharmacology and Experimental Therapeutics SP 613 OP 620 DO 10.1124/mol.112.082602 VO 83 IS 3 A1 Satoki Karasawa A1 Motoki Azuma A1 Takeshi Kasama A1 Satoshi Sakamoto A1 Yasuaki Kabe A1 Takeshi Imai A1 Yuki Yamaguchi A1 Keisuke Miyazawa A1 Hiroshi Handa YR 2013 UL http://molpharm.aspetjournals.org/content/83/3/613.abstract AB Vitamin K2 (VK2, menaquinone) is known to have anticancer activity in vitro and in vivo. Although its effect is thought to be mediated, at least in part, by the induction of apoptosis, the underlying molecular mechanism remains elusive. Here, we identified Bcl-2 antagonist killer 1 (Bak) as a molecular target of VK2-induced apoptosis. VK2 directly interacts with Bak and induces mitochondrial-mediated apoptosis. Although Bak and Bcl-2-associated X protein (Bax), another member of the Bcl-2 family, are generally thought to be functionally redundant, only Bak is necessary and sufficient for VK2-induced cytochrome c (cyt c) release and cell death. Moreover, VK2-2,3 epoxide, an intracellular metabolite of VK2, was shown to covalently bind to the cysteine-166 residue of Bak. Several lines of evidence suggested that the covalent attachment of VK2 is critical for apoptosis induction. Thus this study reveals a specific role for Bak in mitochondria-mediated apoptosis. This study also provides insight into the anticancer effects of VK2 and suggests that Bak may be a potential target of cancer therapy.