In all co-IP assays, the loading percentage (to whole cell lysate) is 1% for input and 12.5% for IP samples. Immunoprecipitation using an anti-V5 antibody in HEK-293-R301K cells transfected with V5-tagged wild type APE1-, R301F APE1-, and R301K APE1-expressing plasmids. Cells were maintained under standard culture conditions (a) or treated with H2O2 (200 μM for 1 h) (c)/menadione (10 μM for 1 h (e) to increase APE1 arginine methylation. Bar chart for relative pulled-down Tom20 protein in normal cells (b), H2O2-treated cells (d), and menadione-treated cells (f). Co-IP assay for APE1 and Tom20 purified proteins using anti-APE1 antibody (g). APE1 was methylated through in vitro methyl incorporation assay (g, second and third lane). APE1 samples in the first lane, fourth lane and fifth lane omitted SAM during in vitro methyl incorporation assay. (h) Bar chart for relative pulled down Tom20 in co-IP assays.