Cellular Uptake of Arginine-Rich Peptides: Roles for Macropinocytosis and Actin Rearrangement

The use of membrane-permeable peptides as carrier vectors for the intracellular delivery of various proteins and macromolecules for modifying cellular function is well documented. Arginine-rich peptides, including those derived from human immunodeficiency virus 1 Tat protein, are among the representative classes of these vectors. The internalization mechanism of these vector peptides and their protein conjugates was previously regarded as separate from endocytosis, but more recent reevaluations have concluded that endocytosis is involved in their internalization. In this report, we show that the uptake of octa-arginine (R8) peptide by HeLa cells was significantly suppressed by the macropinocytosis inhibitor…