Figure 1.

Full-length PNKP is present in mitochondria. (A) Mitochondria were isolated from rat liver and wild-type (WT) and PNKP knock-down (KD) A549 cells. Mitochondrial protein extracts were immunoblotted with a monoclonal antibody to PNKP. Antibodies against PCNA (nuclear marker) and COX IV or VDAC1 (mitochondrial markers) were used to ensure the purity of the mitochondrial preparation. (B) Purified human PNKP protein is sensitive to proteinase K, and is completely digested even at the lowest concentration used (10 µg ml⁻¹). (C) PNKP signal detected in purified mitochondria isolated from A549 cells is protected from proteinase K digestion. Proteins in nuclear extracts are shown on the left and purified PNKP protein on the right.