Cell penetrating peptides (CPPs) with intrinsic biological activities offer a novel strategy for the modulation of intracellular events. QSAR analysis identified CPPs within human cytochrome c. Two such sequences, Cyt c(77-101) and Cyt c(86-101), induced tumor cell apoptosis, thus mimicking the role of Cyt c as a key regulator of programmed cell death. Quantitative analyses confirmed that Cyt c(77-101) is an extremely efficient CPP. Thus, Cyt c(77-101) was selected for modification to incorporate target-specific peptidyl motifs. Chimeric N-terminal extension with a target mimetic of FG nucleoporins significantly enhanced the apoptogenic potency of Cyt c(77-101) to a concentration readily achievable in vivo. Moreover, this construct, Nup153-Cyt c, facilitates the dramatic redistribution of nuclear pore complex proteins and thus propounds the nuclear pore complex as a novel target for the therapeutic induction of apoptosis.
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