| First Author | Jetté L | Year | 1995 |
| Journal | Biochem J | Volume | 305 ( Pt 3) |
| Pages | 761-6 | PubMed ID | 7848274 |
| Mgi Jnum | J:22859 | Mgi Id | MGI:70747 |
| Doi | 10.1042/bj3050761 | Citation | Jette L, et al. (1995) Isoform I (mdr3) is the major form of P-glycoprotein expressed in mouse brain capillaries. Evidence for cross-reactivity of antibody C219 with an unrelated protein. Biochem J 305(Pt 3):761-6 |
| abstractText | P-glycoprotein (P-gp) is expressed in various non-cancerous tissues such as the endothelial cells of the blood-brain barrier. We used several monoclonal antibodies (mAbs) and isoform-specific polyclonal antibodies to establish which P-gp isoforms are expressed in isolated mouse brain capillaries. P-gp class I isoform was detected in capillaries with a Western immunoblotting procedure using a specific antiserum. No immunoreactivity was observed with either class II- or class III-specific antisera. Immunoreactivity was observed with mAb C219. However, this antibody detected two distinct immunoreactive proteins (155 and 190 kDa) in the isolated brain capillaries. These two proteins comigrated as a broad band when the samples were submitted to heat prior to gel electrophoresis. The glycoprotein nature of these two antigens was evaluated by their sensitivity to N-glycanase treatment. Following this treatment, the size of the proteins was reduced from 190 and 155 kDa to 180 and 120 kDa, respectively. Triton X-114 phase-partitioning studies showed that the 190 kDa immunoreactive protein was poorly solubilized by Triton X-114, while the 155 kDa protein was partitioned in the detergent-rich phase. In labelling experiments, only the 155 kDa protein was photolabelled with [125I]iodoarylazidoprazosin. These results show that a 190 kDa protein detected by antibody C219 is an antigen unrelated to the three P-gp isoforms presently known. Cross-reactivity of C219 with an unrelated protein emphasizes the fact that more than one antibody should be used in the assessment of P-gp expression in cell lines and tissues. |
