Fig. 1

The schematic diagram for the research strategy and the detection of endogenous pY39 αβ-syn peptides. a The experimental strategy for pY39 αβ-syn peptide enrichment using an anti-phosphotyrosine antibody. CSF proteins were digested with Lys-C and trypsin followed by phosphotyrosine peptide enrichment. To validate the detection of the endogenous pY39 αβ-syn peptide, a heavy pY39 αβ-syn standard peptide was added before PRM analysis. The endogenous light and heavy standard pY39 αβ-syn peptides were monitored under PRM mode followed by a quantification using Skyline software. b The extracted chromatogram of y ion series from either endogenous or heavy standard pY39 αβ-syn peptide