Table 1.
Surrogate peptides used to quantify protein expression and MRM transitions used for LC–MS/MS detection in this study.
| Protein | Peptide sequence | IS | RT (min) | Q1 [M+2H]2+ (Da) | Q3 [M+H]+ (Da) |
|---|---|---|---|---|---|
| ATP7A | LGAIDVER | MRP2-H | 12.8 | 436.7 | 759.4 |
| ATP7B | AIATQVGINK | MRP2-H | 11.4 | 507.8 | 759.4 |
| CTR1 | SQVSIR | MRP2-H | 7.9 | 345.2 | 474.3 |
| MRP2 | GINLSGGQK | MRP2-H | 10.0 | 437.2 | 703.4 |
| MRP4 | APVLFFDR | MRP4-H | 20.2 | 482.8 | 697.4 |
| MATE1 | HVGVILQR | MRP4-H | 11.4 | 461.3 | 685.4 |
| OCT1 | VPPADLK | MRP2-H | 9.0 | 370.2 | 640.4 |
| OCT2 | FLQGLVSK | OCT2-H | 16.1 | 446.3 | 503.3 |
| OCT3 | TTVATLGR | MRP2-H | 10.3 | 409.7 | 616.4 |
| P-gp | IATEAIENFR | OCT2-H | 15.8 | 582.3 | 979.5 |
| MRP2-H | GINL∗SGGQK | – | 10.0 | 440.7 | 710.4 |
| MRP4-H | APVL∗FFDR | – | 20.2 | 486.3 | 704.4 |
| OCT2-H | FLQGL∗VSK | – | 16.1 | 449.8 | 751.5 |
Membrane protein fractions were digested with trypsin per Materials and Methods to quantify transporter expression. Multiple reaction monitoring transitions used for detection are listed as doubly-charged parent ion (Q1) and singly charged fragment ion (Q3) used for quantification. ∗13C/16N heavy isotope labeled amino acid internal standards (IS). RT, retention time for liquid chromatography method. –Not applicable.