Fig. 5

Aβ oligomers are present in highly stable CSF-PS1 complexes. a CSF samples from eNC and sAD subjects were precleared with protein A-Sepharose (T: total), and then immunoprecipitated with the anti CTF-PS1 00/2 antibody. The precipitated proteins (IP) were probed in immunoblots with the antibody indicated (98/1 for NTF-PS1 and 6E10 for Aβ). Note that oligomeric Aβ species co-immunoprecipitate and interact with CSF-PS1 complexes in both eNC and sAD. None immunoreactivity was resolved in negative controls incubated with beads in the absence of antibody (not shown). b CSF-PS1 complexes were fractionated by sucrose gradient centrifugation, and the fractions containing highly stable (Hs) or unstable (Us) PS1 complexes were pooled, dialyzed and concentrated by ultrafiltration. Representative sedimentation profiles illustrate the fractions selected for peak isolation. The enriched CSF-PS1 complexes were then immunoprecipitated with the 00/2 antibody and assayed in immunoblots probed with the 6E10 antibody against Aβ (insert). Representative blots reveal that Aβ oligomers are mainly present in peak fractions containing highly stable PS1 complexes (illustrative examples from two different experiments)