ATAD3A KO HeLa cells were harvested for mitochondrial isolation. Purified mitochondria were treated with the indicated gradient concentration of proteinase K for 20 min on ice, and then were analyzed by Western blotting with anti-ATAD3, anti-Tom20 (OMM), anti-Tim23 (IMS), and anti-HSP60 (matrix) (K). Relative protein levels of proteins in (K) were further evaluated by densitometry analysis using ImageJ software. Relative trends of proteolysis of indicated mitochondrial proteins from ATAD3A KO HeLa cells were shown (L). Data are presented as mean ± SD (n = 3 independent experiments). 