Bax protein belongs to the Bcl-2 family. It is pro-apoptotic and the most common form is Bax α. When a cell receives death stimuli, Bax... Show moreBax protein belongs to the Bcl-2 family. It is pro-apoptotic and the most common form is Bax α. When a cell receives death stimuli, Bax protein will oligomerize and target to mitochondria. Another isoform of Bax called Bax 2, which has lost exon 2 and has a frame shift mutation, is verified to be more potent in inducing apoptosis than Bax α. Here, we would like to understand more about Bax 2 mitochondria targeting ability compared to the more common Bax α form. We first set up a cell-free system which contained purified Bax protein and purified mitochondria. The mitochondrial binding protein was identified using fractionation and Western blot with Bax isoformspecific antibodies. Integration of Bax protein into the mitochondrial membrane was determined using the alkaline stripping method. The results suggest that the majority of Bax α targeted and integrated into the mitochondria membrane, while the majority of Bax 2 did not target to mitochondria in the cell-free system. This may suggest that Bax 2 might need additional help from certain cytosol components such as co-factors to target to mitochondria or that Bax 2 induces cell death through a mechanism other than mitochondrial targeting. M.S. in Biology, May 2011 Show less
