Figure 2

AβMRF forms SDS-stable oligomers in yeast. (A) Immunoblot analysis of lysates from sup35Δ cells containing prionized NMRF ([PSI+]) or other indicated constructs. Lysates were treated with 1% SDS for 7 mins at room temperature and resolved by electrophoresis in agarose. Immunoblot analysis was performed using anti-RF antibodies, followed by stripping and staining with anti-Aβ antibodies. The positions of molecular weight standards, treated identically to the experimental samples, are shown (calc., calculated position). AβMRF formed SDS-stable low-n oligomers that largely disappeared after the introduction of the F19,20T (Aβm1MRF) and F19,20T/I31P (Aβm2MRF) mutations into the Aβ₄₂ portion of the fusion protein. The decreased efficacy with which anti-Aβ antibodies recognized oligomers of AβMRF suggests that oligomerization occurred through the Aβ₄₂ portion of the fusion protein. (B) 5 mg of amyloid fibers of Aβ₄₂ peptide were treated with 1% SDS, resolved in agarose and analyzed by immunoblotting with anti-Aβ antibodies. Only a fraction of Aβ42 fibres can enter the 1.5% agarose gel. (C) Same as in (A) but the samples were resolved in an acrylamide gel. Asterisk denotes non-specific antibody interaction.