Correlation between the expression of UNG1 variants, mtDNA content, and expression of the mtDNA. Cells expressing wtUNG1 or either the Y147A or the N204D mutant were induced with empirically chosen regimens (see text), and mtDNA content (a, c, and f) as well as expression of the myc-tagged UNG1 variants and mtDNA-encoded MT-COI subunit were monitored by western blotting. DNA ligase III (Lig3) and HSP60, loading controls. (a and b) Cells were induced to express wtUNG1 for 24 h with 2 µg/ml of doxycycline. (c, d, and e) Cells were induced to express the Y147A mutant with 0.5 µg/ml of doxycycline for either 1 h (D) or 24 h. (e, f, g, and h) Cells were induced to express the N204D mutant with 2 µg/ml of doxycycline for either 3 h (g) or 24 h. (h) Plotted values are means of triplicate measurements ± SD.