F: Ubc9 wt or D100A are equally active in RanBP2 - dependent SUMOylation. Assays were with 650 nM YFP-SP100, 110 nM of E1, 25 Ubc9, 40 nM RanBP2ΔFG and 3,5 µM SUMO1 (Left panel) or SUMO2 (Right panel). 