Fig 2: PRMT1 methylates APE1 in vitro.In all co-IP assays, the loading percentage (to whole cell lysate) is 1% for input and 12.5% for IP samples. (a) Immunoprecipitates extracted from HeLa cells using an anti-APE1 antibody were detected using arginine methylation-specific antibodies. (b) In vitro methyl incorporation assay. Proteins were resolved by SDS-PAGE, stained with Coomassie blue (left panel), dried, and analyzed by autoradiography (right panel). BSA, negative control; Histone, positive control; (c) Co-immunoprecipitation assay of purified recombinant APE1 and PRMT1 proteins. Left panel, anti-APE1 antibody; right panel, anti-PRMT1 antibody. Anti-APE1 and anti-PRMT1 antibodies were used for western blotting. (d) Co-immunoprecipitation assay of APE1 and PRMT1 proteins in HeLa cell lysates. Left panel, anti-APE1 antibody; right panel, anti-PRMT1 antibody. Anti-APE1 and anti-PRMT1 antibodies were used for western blotting. (e) 3H labeled-methyl incorporation assay for HeLa cells with or without MS023 treatment, respectively. (f) Bar chart for (e) showing relative methylated APE1 comparing to cells without MS023 treatment (p < 0.001).