Fig. 5: Inhibition of substrate degradation by free ubiquitin chains.
Degradation of substrate proteins with three different ubiquitin chain modifications by the indicated proteasome types was followed under single-turnover conditions (5 nM substrate, 25 nM) in the presence of 1 mM ATP at 30 °C by measuring GFP fluorescence. Increasing concentrations of ubiquitin chains were added and the initial rates of the reactions determined by curve fitting. Graphs show initial rates of degradation as a percentage of the rate in the absence of competitor. a Ub5(K48)-GFP-35 on WT proteasome, b Ub5(K48)-Ub-GFP-35 on Rpn10 proteasome, c Ub4(lin)-GFP-35 on Rpn13 proteasome inhibited by free ubiquitin chains. Error bars show standard errors derived from at least three replicate experiments. Source data are provided as a Source Data file.
