The impermeability of cell plasma membranes is a major barrier to using drugs to kill tumor cells or affect cells transgenically. CPPs are peptides that were discovered to have the ability to transport themselves (and even attached cargo) into cells. How they get into cells is still a mystery, but CPPs all have multiple positively charged groups. Which of the following membrane components are they most likely to be interacting with?
A. phospholipid heads
B. phospholipid tails
C. intrinsic membrane proteins
D. cholesterol