Fig. 1.

(A) Schematic diagram of E. coli expression vectors for dsRED, dsRED-9R, and dsRED-9K. (B) Cell penetrating capacity of dsRED, dsRED-9R, and dsRED-9K in both an immortalized cell line and primary cells which were cultured in 24-well plates and treated with 20 μg/ml of either dsRED-9R or dsRED-9K proteins. After 6 hrs of incubation, fluorescent images were captured with matching exposure to test the efficiency of penetration. Penetrations of both dsRED-9R and dsRED-9K, but not dsRED alone, were observed in all three target cell types. (C) Penetrating efficiency of purified dsRED-9K was compared to that of the extracts prepared from HEK293 cells expressing pCMV dsRED-9K. Human fibroblasts on 12-well plates were treated with purified dsRED-9K and whole cell extracts of HEK293 cells transfected with dsRED-9K construct. After 6 hrs of incubation, fluorescent images were captured. Purified dsRED-9K showed better distribution of signals in the cell body and surface.