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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.