Recombinant Cell-Permeable Puromycin N-Acetyltransferase Confers Puromycin Resistance by Direct Protein Transduction

and purified to homogeneity. The purified TAT-PAC protein retained enzymatic activity, with a specific activity of 197 nmol/min/mg. Intracellular delivery of TAT-PAC was confirmed using confocal microscopy and flow cytometry, employing an RFP (red fluorescent protein)-tagged TAT-PAC fusion protein. Treatment of HEK293 and SY5Y cells with TAT-PAC resulted in increased cell viability in the presence of puromycin, demonstrating its functionality as a selection marker. This study suggests the potential application of cell-permeable PAC protein for selection of co-delivered therapeutic or gene-editing proteins in mammalian cells, providing a promising alternative to traditional genetic selection methods.