Fig. 4.

Methylation stoichiometries of soluble tau proteins purified from cognitively normal middle age (CN^MA) and elderly (CN^E) cases, and of aggregated tau from AD cases were determined by targeted metabolomics analysis. Each circular point represents methylation stoichiometry in a single biological replicate in units of mol residue/mol tau protein, whereas each bar represents the mean of all replicates. *, p < 0.05 compared to zero methylation stoichiometry, one-way ANOVA; #, p < 0.05 compared pairwise to all methyl-amino acid forms, ANOVA with Tukey’s post hoc test; n.s., not significant.