Figure 3From: A study protocol for quantitative targeted absolute proteomics (QTAP) by LC-MS/MS: application for inter-strain differences in protein expression levels of transporters, receptors, claudin-5, and marker proteins at the blood–brain barrier in ddY, FVB, and C57BL/6J micePrinciple of peptide selection by selected/multiple reaction monitoring (SRM/MRM) mode of triple quadrupole mass spectrometry (QqQ MS). The selection of the targeted peptide by two mass filters (Q1 and Q3) results in the reduction of noise from the complex peptide sample. Each target peptide is monitored by four different SRM/MRM transitions, which consist of a parent ion (Q1) and four different daughter ions (Q3) for accurate and reliable quantification.Back to article page