Table I.
Examples of cell-penetrating peptides classified on the basis of their origin with indication of their sequence and key feature.
| Protein group | Protein name | Sequence | Characteristics | Refs. |
|---|---|---|---|---|
| Natural | TAT | GRKKRRQRRRPPQ | Transcriptional regulator of HIV. | (11,12) |
| pVEC | LLIILRRRIRKQAHAHSK | Mouse's catherin sequence. | (16) | |
| Chimeric | Transportan | GWTLNSAGYLLGKINLKALAALAKKIL | Protein formed by the combination of neuropeptide galanin and wasp's botulinum toxin, mastoparan, through a lysine residue. | (17) |
| MPG | GALFLGFLGAAGSTMGAWSQPKKKRKV | Protein obtained by the fusion of the transmembrane glycoprotein of HIV, gp41, with SV40 virus T-antigen. | (18) | |
| Synthetic | MAP | KLALKLALKALKAALKLA | Amphipathic protein created de novo from lysine, arginine and leucine residues. | (19) |
| R6W3 | RRWWRRWRR | Artificial peptide created de novo based on the structure of penetrin. | (20) |
pVEC, 18 amino acid CPP derived from murine vascular endothelial-cadherin; HIV, human immunodeficiency virus; MAP, model amphipathic protein.