Schematic model illustrating internalization of TAT-SA-PPAA in the human cell. After interaction with the cell surface, TAT-SA enters the cell via clathrin-mediated endocytosis or macropinocytosis (1), followed by transport to endosomal vesicles. Later, at low pH (≤6.5), PPAA induces the escape of TAT-SA from endosomes (2) and the nuclear localization sequence of the TAT peptides mediates the nuclear import of the construct (3). In the absence of PPAA polymer most of TAT-SA remains trapped in endosomes and is transported and further degraded in lysosomes.
Rinne et al. BMC Biotechnology 2007 7:1 doi:10.1186/1472-6750-7-1