TOP1 is SUMOylated at lysine-117 with SUMO1 (Mao et al. 2000, Mo et al. 2002, Rallabhandi et al. 2002, Impens et al. 2014). SUMOylation is observed in response to the topoisomerase inhibitor camptothecin and causes nucleolar delocalization of TOP1.
SUMO transferase activity of SUMO1:C93-UBE2I [cytoplasm]