Table 1.
Protein quantitation
| Protein | Mouse ABCB1A/B | Mouse ABCB1A | Human ABCB1 | Mouse ATP1A1 | Mouse ATP1A2 | Mouse ATP1A3 | Mouse GFAP |
|---|---|---|---|---|---|---|---|
| Peptide | IATEAIENFR | LANDAAQVK | FYDPLAGK | IVEIPFNSTNK | GIVIATGDR | GVVVATGDR | LDQLTANSAR |
| Strain | Concentration [fmol/µg total protein] (CV [%]) | ||||||
| LoD/LoQ | 0.05/0.16 | 0.08/0.23 | 0.23/0.70 | 0.58/1.73 | 0.04/0.12 | 0.07/0.25 | 0.19/0.28 |
| hABCB1 | <LoD | <LoD | <LoQ | 131.5 (34.9) | 86.0 (19.2) | 435.2 (26.9) | 1.0 (14.0) |
| hABCB1–/– | 0.44 (30.6) | 0.36 (14.4) | <LoD | 106.8 (17.0) | 78.8 (13.8) | 371.6 (11.0) | 1.0 (32.0) |
| WT | 0.72 (13.7) | 0.64 (12.1) | <LoD | 119.9 (16.6) | 80.9 (12.6) | 392.2 (15.6) | 0.8 (25.1) |
Reference proteins according to Zhang et al. [41]:
- Neurons, astrocytes, endothelial cells express ATP1A1.
- Both astrocytes and endothelial cells express ATP1A2, but endothelial cells in very low amounts.
- Neurons express ATP1A3.
- Astrocytes express GFAP.
The concentrations of different markers are not different between the samples and thus show the homogeneity of their cell composition. Therefore, the concentrations of ABCB1 proteins in the samples can be compared with each other. The QuaSAR plugin (Mani et al. [42]) was used to calculate the limit of detection and limit of quantitation.
CV (%) – biological and experimental variability, LoQ – lower limit of quantitation, LoD – lower limit of detection