Efficient intracellular delivery of an exogenous protein GFP with genetically fused basic oligopeptides

Several oligopeptides, derived from certain proteins, translocate as a form fused to small molecules or exogenous proteins across the plasma membrane into cells. Some of these oligopeptides, the so-called protein-transduction domains (PTDs), contain a high proportion of basic residues. The transloca tion of some of these basic PTDs, such as oligoarginines, has been studied as chemically fused forms to other organic compounds. In this study, we als o tested to determine whether or not oligoarginines, when fused genetically to an exogenous protein such as GFP, are also able to translocate efficien tly across the plasma membrane. The oligoarginine Rn (n = 5,6,7,8,9)-GFP fu sion proteins were translocated quite efficiently, and the transduction eff iciency increased in proportion to the number of arginine residues. However , the cellular uptake of the oligolysine-GFP fusion proteins was less effic ient than that of the corresponding oligoarginine-GFP fusion proteins. When fused to GFP, the translocation efficiency of R5 was similar to that of Ta t(49-57)(RKKRRQRRR). This finding suggests that the arginine homo-oligopept ide is more efficient than other PTDs which contain a mixture of basic resi dues. On the other hand, both the K9- and Tat(49-57)-GFP fusion proteins we re transduced with similar efficiencies. It appears that basic oligopeptide s may be useful for the efficient translocation of diverse exogenous protei ns as genetically fused forms.