Fig. (4) Competition with untagged peptide antagonists, R18 and pS967-ASK1, in the 14-3-3γ/R18 AlphaScreen assay. Biotin-14-3-3γ (5 nM) and GST-R18 (15 nM) were incubated with increasing concentrations of untagged antagonists at RT for 1 hr. After incubation for 1.5 hr upon addition of donor and acceptor beads, Alpha signals were recorded. (A) Competition with the R18 peptide or the mutated control (R18Lys) peptide. (B) Competition with pS967-ASK1 or the non-phosphorylated control (ASK1) peptide. The y-axis of the graph represents the percentage of the control. The control is defined by maximal Alpha signal obtained in the absence of any inhibitor with background counts subtracted. Data are expressed as means ± SD from triplicate determinations.