Figure 2.

The effects of clusterin on the aggregation of Aβ_1–40. (a) Fraction of oligomers detected in solution during the aggregation of Aβ_1–40 with and without clusterin (Aβ_1–40 and clusterin are both at a concentration of 600 nM, n=3, error bars are s.e.m.). (b) TIRFM image of the species present after 24 h of aggregation of a 2 μM solution of Aβ_1–40 without clusterin (left). TIRFM image of a 2 μM solution of Aβ_1–40 after 24 h of aggregation but with 2 µM clusterin added 4 h after the start of the reaction, during the fibril growth phase (right). An approximately 50% reduction in the average size of species present is observed in the presence of clusterin (from 1400 ± 200 nm without clusterin to 780 ± 60 nm with clusterin, s.e.m., P-value is 0.01, two-sample independent, two-tailed, t-test). Scale bars are 5 µm. (c) Fractions of species formed during the aggregation of a 2 μM solution that are oligomeric and that are in Aβ:clusterin complexes. (n=3, error bars are s.e.m.). (d) Proportion of Aβ:clusterin complexes persisting at 10–20 nM (total peptide concentration) at 21 °C. Complexes were formed between clusterin and oligomers from both aggregation and disaggregation reactions. For both traces, n=3, error bars are s.e.m. There is no statistically significant change in the proportion of complexes with oligomers formed during either the disaggregation experiment (P-value of 0.77, ANOVA single-factor) or the aggregation experiment (P-value of 0.99, ANOVA single-factor).