ABSTRACT
Cell-Permeable Activity of BCPs ........................................................ 472
27.5 Effective BCP Concentration for Cell Permeability and
Cell Death Suppression ........................................................................ 473
27.6 Time-Dependent Change of BCP Cellular Uptake .............................. 474
27.7 Temperature Influence on BCP Cellular Uptake .................................. 474
27.8 Comparison of BCP and Arginine-Rich Peptide Toxicity .................. 475
27.9 Cargo Delivery Activity of BIPs .......................................................... 478
27.10 Conclusions and Future Studies ............................................................ 478
Acknowledgments .............................................................................................. 479
References .......................................................................................................... 479
Cell-permeable Bax-inhibiting peptides (BIPs) were discovered as a result of
identifying the minimal element of Ku70 needed to bind and inhibit Bax
(Figure 27.1).1,2 Bax is a key apoptosis mediator in mammalian cells and is
ubiquitously expressed in almost all cell types.3,4 In a healthy cell, Bax resides in the
cytosol. Apoptotic stress, however, induces Bax translocation from the cytosol to
the mitochondria, triggering mitochondrial-dependent apoptosis by promoting the
release of apoptogenic factors from the mitochondria.5 The mechanism of the
mitochondrial translocation of Bax from the cytosol is unknown. We employed a
yeast-based functional screening system to find Bax inhibitors using a human
cDNA expression library,6,7 and Ku70 was identified as a new Bax suppressor.8
