BIM-BAD-AND-BAX, ET AL. “Many regulators of apoptosis are located in the mitochondrion or in the mitochondrial inter-membrane space (caspases 2, 3, and 9, cytochrome c, Bcl-2, Bcl-XL, Bad, Bax, Bak, Bim, Smac, HtrA2, AIF). However, we do not find these or homologous components (except HtrA) in contemporary bacteria.”
http://mcb.berkeley.edu/courses/mcbc245/MCBC245PDFs/Jan31/Huettenbrenner2003.pdf