Membrane-permeable arginine-rich peptides and the translocation mechanisms.

The intracellular delivery of proteins and other bioactive molecules using membrane-permeable carrier peptide vectors opens the possibility of establishing novel methods of elucidating and controlling cell functions with therapeutic potentials. One of the most typical peptide vectors is a short, arginine-rich peptide segment derived from the human immunodeficiency virus (HIV)-1 Tat protein. We have shown that not only the Tat peptide, but also various arginine-rich oligopeptides possess very similar characteristics in translocation and abilities as a delivery vector. This review summarizes the structures of these peptide vectors, especially the Tat and other arginine-rich peptides, and the current understanding of their internalization mechanisms.