  Cell-penetrating peptides (CPPs) such as HIV's trans-activating
transcriptional activator (TAT) and polyarginine rapidly pass through the
plasma membranes of mammalian cells by an unknown mechanism called
transduction. They may be medically useful when fused to well-chosen chains of
fewer than about 35 amino acids. I offer a simple model of transduction in
which phosphatidylserines and CPPs effectively form two plates of a capacitor
with a voltage sufficient to cause the formation of transient pores
(electroporation). The model is consistent with experimental data on the
transduction of oligoarginine into mouse C2-C12 myoblasts and makes three
testable predictions.
