TRIM26 can ubiquitylate NEIL1, NTH1, OGG1, and NEIL3 in vitro. In vitro ubiquitylation of (A) His-tagged NEIL1 (4.6 pmol), (B) His-tagged NTH1 (5.8 pmol), (C) His-tagged OGG1 (5.2 pmol), and (D) His-tagged NEIL3 (3 pmol) by His-tagged TRIM26 (11 or 22 pmol). All in vitro ubiquitylation reactions were performed in the presence of E1 activating enzyme (0.7 pmol), H5a, H5b, and H5c E2-conjugating enzymes (2.5 pmol), and ubiquitin (0.6 nmol), and were subsequently analyzed by SDS-PAGE and immunoblotting using the respective antibodies. Molecular-weight markers are indicated on the left-hand side of the blots, and the positions of unmodified and ubiquitylated proteins (e.g., NEIL1ub) are displayed.