Fig. S5.
Redundancy between clusters of phospho-sites within APC1. Fluorescence scans of SDS/PAGE gels loaded with ubiquitination reaction products using fluorescent substrate cyclin B NTD (CycBNTD*). (A) Phospho-mimicking mutations in none of the tested individual APC1 clusters are required for APC/C–CDC20 activation in the absence of phospho-mimicking mutations in other subunits, suggesting redundancy between at least two APC1 clusters. (B) As in A, but in the presence of phospho-mimicking mutations in other subunits. (C) Phospho-mimicking mutations in APC1 clusters 4 or 5, located in the APC1(296–401) loop, are sufficient for APC/C–CDC20 activation in the presence of phospho-mimicking mutations in other subunits. The other pE_APC1wt_clXpE complexes show only slightly higher APC/CCDC20 activity than WT. Cropped lanes are indicated by a dashed line.