Studies show that exogenous Tat protein is able to translocate through the plasma membrane and to reach the nucleus to transactivate the viral genome. The HIV-1 TAT (48-60) peptide, which contains the basic domain of the full length peptide only, retains the full translocation activity and even appears more efficient in terms of nuclear localization when compared with the other active peptides at the standard dose of 1 mM. Cell-penetrating peptides are regarded as promising vectors for intracellular delivery of large, hydrophilic molecules. An apparently endocytotic uptake of HIV-1 TAT (48-60) is observed by confocal laser scanning microscopy. HIV-1 TAT (48-60) induces the formation of rodlike, presumably inverted micelles in DMPC, which may represent intermediates during the translocation across eukaryotic membranes.
