FIGURE 2.

Extracted ion chromatogram of the PRM four most intense fragment ions identified from (A) the synthetic non-labeled peptide DSSFNSAYNLPIPR, (B) an endogenous peptide sample derived from a mature green tomato. (C) XIC of the combined fragment ions of the endogenous peptide (red peak) DSSFNSAYNLPIPR of the protein SlETR4 in a mature green tomato peptide sample and the combined fragment ions of its heavy labeled peptide (blue peak) spiked in the sample. (D) XIC of the four most intense fragment ions used for quantification of the endogenous peptide and (E) the equivalent fragments for the heavy labeled peptide. All data were analyzed by the Skyline software.