Fig. 1

Measuring acetylation stoichiometry. a Diagram of the method used to measure acetylation (Ac) stoichiometry. b The degree of quantification error as determined by the fraction of SILAC ratios at each concentration of chemically acetylated peptides that was not consistent with SILAC ratios measured in at least one different concentration of chemically acetylated peptides. c The correlation between stoichiometry measured in independent experimental replicates. The number of peptides (n), Pearson’s correlation (r), and P-value (P) of correlation are shown. d Low absolute variability between experimental replicates. The histogram shows the distribution of Log2 ratios of stoichiometry in Experiment 1/Experiment 2 (Exp.1/Exp.2). e The correlation between stoichiometry measured using partial chemical acetylation (PCA) and absolute quantification (AQUA) peptide standards. f Low absolute variability between stoichiometry measurements made by PCA and AQUA. g Validation of stoichiometry measurements using recombinant acetylated (100%) proteins as a spike-in standard. Stoichiometry was measured at two different concentrations of spike-in protein (SILAC light, red) compared to SILAC heavy-labeled HeLa (blue) for each acetylation site. Source data are provided as a Source Data file