Fig. 5: Design of the immunoassays.

a C231D181, b C231D217 assay. T181: tau phosphorylation at threonine 181, T231: tau phosphorylation at threonine 231, T217 tau phosphorylation at threonine 217, SBG: streptavidin β-galactosidase, RGP: β-D-galactopyranoside. 2-step protocol workflow (C231D181 assay): 1) Sample incubation with a mixture of bead-conjugated capture antibody and biotinylated detector antibody, 2) Incubation with SBG; 3-step protocol workflow (C231D217 assay): 1) Sample incubation with bead-conjugated capture antibody, 2) Incubation with biotinylated detector antibody, 3) Incubation with SBG. Subsequently, immunocomplexes are resuspended in RGP (SBG substrate), resulting in generation of the fluorescent signal.