Specificity of phosphorylation state-specific antibodies towards peptide antigens
The phosphopeptides described in Fig. 1, containing phospho-Thr654 (closed squares), phospho-Ser655 (open squares), phospho-Thr668 (closed circles), or dephospho-APP645–694 (open circles) and APLP2717–764 (open triangles), were spotted on nitrocellulose filters. Membranes were probed with (a) pAbT654, (b) pAbS655, (c) pAbT668, or (d) G-369 antibodies, followed by [125I]protein A, and autoradiography was performed. Radioactivity was quantified with a Molecular Dynamics PhosphorImager. For each antibody, results were calculated as a percentage of the maximal value obtained.