Fig. 4
From: A common mechanism of proteasome impairment by neurodegenerative disease-associated oligomers
A11(+) oligomers cannot inhibit PA26 or PA28αβ induced gate opening. a–c 20S Proteasome activity with and without the proteasome activator PA26 (1 μg/100 μl) was determined in the presence of A11(+) oligomers from Aβ*56 (1.5 μM, a), α-Syn (0.1 μM, b), or Htt-53Q (0.1 μM, c). Broken graphs are used to show the extent of 20S inhibition, while still showing the extent of PA26 activation. d Proteasome activity in the presence of increasing concentrations of PA26 with and without A11(+) Aβ*56 (1.5 μM). The sigmoidal equation was fit to the averages from three independent experiments (normalized to % activity) performed in triplicate, error bars ± SEM. For a–d, the 20S proteasome activity (nLPnLD-amc hydrolysis, rfu/min) was normalized to 20S control activity without activator. e Proteasome activity with PA26 activator (1 μg/100 μl) in the presence of increasing concentrations of Aβ*56 (left). Activity of 20S proteasome (without PA26) with 1.5 μM Aβ*56 is shown at right. f Same experiment as in a, with human PA28αβ replacing PA26. The concentrations of oligomers are calculated based on the respective monomeric peptide/protein mass. All controls contained an equal volume of buffer identical to that of the respective aggregates. The data are representative of three or more independent experiments performed in triplicate. Error bars represent ± standard deviation
