Which of the Following Proteins Activates the Mitochondrial Pathway of Apoptosis

Question

Which of the following proteins activates the mitochondrial pathway of apoptosis?
A) The tumor suppressor protein p53, when activated in response to extensive DNA damage.
B) The BH3-only protein Bid, when cleaved by the initiator caspase-8 (from the extrinsic pathway).
C) The anti-IAP protein Omi, when activated by dephosphorylation.
D) The BH3-only protein Bad, when activated by dephosphorylation.
E) All of the above.

Accepted Answer

Activated BH3-only proteins or anti-IAP proteins can result in the activation of the intrinsic pathway of apoptosis. In response to DNA damage that cannot be repaired, the tumor suppressor protein p53 activates the expression of genes encoding BH3-only proteins (such as Puma).