UBE2I (UBC9) is SUMOylated at lysine-14 with SUMO1 (Knipscheer et al. 2008). SUMOylation alters the target specificity of UBE2I, decreasing its SUMOylation activity towards RanGAP1 and increasing it towards SP100.
van Dijk, WJ,
SUMO transferase activity of SUMO1:C93-UBE2I [cytoplasm]