F Plot of METRIS rolling parameters of WT and the R149E substituted variant of UBE2R2 isopeptide-linked to the donor Ub compared using one-way ANOVA (* p ≤ 0.05, WT-Ub: 47 beads x 17 rolls n=799, R149E-Ub: 114 beads x 17 rolls n=1938; technical replicates). Error bars: SEM. 