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Table 1 Peptide probe sequences, selected ions for quantification and limit of quantification in isolated brain capillaries of each protein with LC-MS/MS.

From: Attenuation of prostaglandin E2 elimination across the mouse blood-brain barrier in lipopolysaccharide-induced inflammation and additive inhibitory effect of cefmetazole

     MRM transition  
Accession No. Synonym (gene name) Probe sequence Peptide
mass
Q1 Q3-1 Q3-2 Q3-3 Q3-4 Limit of quantification (fmol/μg)
Q3TZN9 Mrp4 APVLFFDR 963.5 482.8 796.4 697.4 584.3 437.2 0.0460
  (Abcc4) APVL* FFDR 970.5 486.3 803.4 704.4 584.3 437.2  
O88909 Oat3 YGLSDLFR 969.5 485.8 807.4 750.4 637.3 550.3 0.163
  (Slc22a8) YGLSDL*FR 976.5 489.3 814.4 757.4 644.3 557.3  
Q9EP96 Oatp1a4 EVATHGVR 867.5 434.7 640.4 569.3 468.3 331.2 0.441
  (Slco1a4) EVATHGV*R 873.5 437.7 646.4 575.5 474.3 337.2  
Q9EPT5 Pgt IFVDYGR 869.0 435.2 756.4 609.3 510.2 395.2 0.312
  (Slco2a1) IFV* DYGR 875.0 438.2 762.4 615.3 510.2 395.2  
  1. The selected peptides were synthesized and their purity was checked with HPLC-UV according to the previous report [26]. The MRM transitions were determined from MS/MS spectra obtained by direct infusion of 1 μM peptide solution at a flow rate of 5 μL/min with a syringe pump (Harvard) into the mass spectrometer. Doubly charged precursor ions were selected (Q1). Four transitions per peptide (Q3-1, -2, -3 and -4), corresponding to high-intensity fragment ions, were selected. The declustering potentials and collision energies were optimized to maximize signal strength. For the stable isotope-labeled peptides, precursor ions and transitions corresponding to those of the unlabeled peptides were selected, with the same declustering potentials and collision energies as for the unlabeled peptides. Bold letters with asterisks indicate amino acid residues labeled with stable isotope (13C and15N). The limit of quantification was defined as the protein expression level which would give a peak area count of 5000 in the chromatogram when a brain capillary sample is measured by LC-MS/MS.