Cell permeable & penetrating Peptides - CPP

Cell Permeable Peptides (CPP) freely cross cell membranes

Efficient transfer of proteins or nucleic acids across cellular membranes is one of the major problems in cell biology.

Cell Permeable Peptides, also known as Protein Transduction Domains (PTDs), are short peptides that can freely move across cell membranes.

Several PTDs have been identified that allow a fused protein to efficiently cross cell membranes in a process known as protein transduction. In addition to their high transduction efficiencies, cell permeable peptides demonstrate low cytotoxicity.

CPP’s are widely used to deliver such cargo as proteins, oligonucleotides, plasmid DNA, RNA, liposomes and anti-cancer drugs into cells.  CPP’s can be attached to cargo either covalently or non-covalently. Delivery efficiency is dependent on size of cargo-CPP complex, nature of CPP, the type of peptide sequence, etc.

CPPs themselves differ in their transduction efficiencies for different cell types and to where they localize within the cell.  For example, TAT transports to the cytosol of HeLa cells, whereas Antennapedia can cross the blood-brain barrier.

Cell permeable peptide sequences are either cationic, amphipathic, or hydrophobic. The suggested mechanisms of CPP entrance into cells includes direct penetration (ie., pore formation, and inverted micelle formation), and endocytosis.