Blk, a BH3-containing mouse protein that interacts with Bcl-2 and Bcl- xL, is a potent death agonist

Abstract

We identified and cloned a novel murine member of the pro-apoptotic Bcl- 2 family. This protein, designated Blk, is structurally and functionally related to human Blk and localized to the mitochondrial membrane, Blk contains a conserved BH3 domain and can interact with the anti-apoptotic proteins Bcl-2 and Bcl-xL Ectopic expression of Blk in mammalian cells induces apoptosis, which can be inhibited by mutations in the BH3 domain and by overexpression of Bcl-2 or Bcl-xL but not by CrmA. The apoptotic activity of Blk is also inhibited by a dominant negative caspase-9, suggesting that Blk induces apoptosis through activation of the cytochrome c-Apaf-1-caspase- 9 pathway.