| First Author | Castillo G | Year | 1995 |
| Journal | Biochim Biophys Acta | Volume | 1262 |
| Issue | 2-3 | Pages | 113-23 |
| PubMed ID | 7599185 | Mgi Jnum | J:26228 |
| Mgi Id | MGI:73892 | Doi | 10.1016/0167-4781(95)00056-m |
| Citation | Castillo G, et al. (1995) A homologue of the mammalian multidrug resistance gene (mdr) is functionally expressed in the intestine of Xenopus laevis. Biochim Biophys Acta 1262(2-3):113-23 |
| abstractText | P-glycoprotein is an integral membrane protein that functions in multidrug resistance (MDR) cells as a drug efflux pump to maintain intracellular concentrations of antitumor drugs below cytotoxic levels. A homologue of the mammalian mdr gene has been isolated and characterized from Xenopus laevis (Xe-mdr). The cDNA was isolated from a tadpole cDNA library using the full length mouse mdrlb cDNA as a probe. The Xe-mdr encodes a protein that is 66% identical to the mouse mdrlb and 68% identical to the human mdrl. The predicted structure of the Xe-mdr gene product identifies twelve membrane spanning domains and two ATP binding sites both of which are the hallmark of the ABC (ATP binding cassette) transporters. Xe-mdr mRNA is expressed as a single message of 4.5 kb and is found predominantly in the intestine. Xe-mdr message is increased 3- to 4-fold in the ileum compared to the rest of the small intestine. In situ hybridization of sequential sections from the small intestine localized the expression of the Xe-mdr to the cells lining the lumenal epithelium. Brush border membrane vesicles prepared from the small intestine of Xenopus laevis effluxed vinblastine in an ATP-dependent manner. Efflux was decreased by verapamil, a known inhibitor of P-glycoprotein function. These studies indicate that the structure of Xe-mdr has been conserved and suggest that the protein has a role in maintaining the function of the normal intestine in Xenopus. |
