ABCB1 p.Asn99Gln
| Predicted by SNAP2: | A: N (53%), C: D (63%), D: D (66%), E: D (63%), F: N (57%), G: D (53%), H: N (61%), I: N (53%), K: D (63%), L: N (57%), M: N (61%), P: D (63%), Q: N (61%), R: D (66%), S: N (61%), T: N (66%), V: N (53%), W: D (71%), Y: N (53%), |
| Predicted by PROVEAN: | A: N, C: N, D: N, E: N, F: D, G: N, H: N, I: N, K: N, L: N, M: N, P: N, Q: N, R: N, S: N, T: N, V: N, W: D, Y: D, |
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[hide] A T3587G germ-line mutation of the MDR1 gene encod... Mol Cancer Ther. 2006 Apr;5(4):877-84. Mutoh K, Mitsuhashi J, Kimura Y, Tsukahara S, Ishikawa E, Sai K, Ozawa S, Sawada J, Ueda K, Katayama K, Sugimoto Y
A T3587G germ-line mutation of the MDR1 gene encodes a nonfunctional P-glycoprotein.
Mol Cancer Ther. 2006 Apr;5(4):877-84., [PMID:16648557]
Abstract [show]
The human multidrug resistance gene 1 (MDR1) encodes a plasma membrane P-glycoprotein (P-gp) that functions as an efflux pump for various structurally unrelated anticancer agents. We have identified two nonsynonymous germ-line mutations of the MDR1 gene, C3583T MDR1 and T3587G MDR1, in peripheral blood cell samples from Japanese cancer patients. Two patients carried the C3583T MDR1 allele that encodes H1195Y P-gp, whereas a further two carried T3587G MDR1 that encodes I1196S P-gp. Murine NIH3T3 cells were transfected with pCAL-MDR-IRES-ZEO constructs carrying either wild-type (WT), C3583T, or T3587G MDR1 cDNA and selected with zeocin. The resulting zeocin-resistant mixed populations of transfected cells were designated as 3T3/WT, 3T3/H1195Y, and 3T3/I1196S, respectively. The cell surface expression of I1196S P-gp in 3T3/I1196S cells could not be detected by fluorescence-activated cell sorting, although low expression of I1196S P-gp was found by Western blotting. H1195Y P-gp expression levels in 3T3/H1195Y cells were slightly lower than the corresponding WT P-gp levels in 3T3/WT cells. By immunoblotting analysis, both WT P-gp and H1195Y P-gp were detectable as a 145-kDa protein, whereas I1196S P-gp was visualized as a 140-kDa protein. 3T3/I1196S cells did not show any drug resistance unlike 3T3/H1195Y cells. Moreover, a vanadate-trap assay showed that the I1196S P-gp species lacks ATP-binding activity. Taken together, we conclude from these data that T3587G MDR1 expresses a nonfunctional P-gp and this is therefore the first description of such a germ-line mutation. We contend that the T3587G MDR1 mutation may affect the pharmacokinetics of MDR1-related anticancer agents in patients carrying this allele.
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196 The SDS-PAGE profile of I1196S P-gp is also very similar to the glycosylation-deficient P-gp that has the three amino acid substitutions, N91Q, N94Q, and N99Q (39).
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ABCB1 p.Asn99Gln 16648557:196:154
status: NEW[hide] Purification and characterization of N-glycosylati... Arch Biochem Biophys. 2001 Apr 1;388(1):171-7. Urbatsch IL, Wilke-Mounts S, Gimi K, Senior AE
Purification and characterization of N-glycosylation mutant mouse and human P-glycoproteins expressed in Pichia pastoris cells.
Arch Biochem Biophys. 2001 Apr 1;388(1):171-7., [PMID:11361134]
Abstract [show]
P-glycoprotein confers multidrug resistance in mammalian cells and basic structure-function studies of it are germane to anti-cancer and anti-AIDS therapy. Pure, detergent-soluble mouse MDR3 and human MDR1 P-glycoproteins have recently been obtained in sufficient quantity for high-resolution structure analysis after expression in Pichia pastoris (N. Lerner-Marmarosh et al. (1999) J. Biol. Chem. 274, 34711-34718). The degree of glycosylation of these preparations was unknown, and was of relevance for crystallization studies. Therefore mutant proteins in which the N-glycosylation sites were eliminated (Asn --> Gln in mouse MDR3 Pgp, Asn --> Gln or Ala in human MDR1 Pgp) were expressed in P. pastoris and purified to homogeneity. Yields of mutant Pgp were the same as for parent wild-type proteins. Nucleotide-binding and catalytic (ATPase) characteristics were completely normal in the mutant proteins. Mass spectrometry indicated that mutant and wild-type proteins did not differ significantly in mass, demonstrating that the wild-type proteins contain no N-glycosylation.
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No. Sentence Comment
44 The N99Q mutation generates a new BciVI restriction site.
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ABCB1 p.Asn99Gln 11361134:44:4
status: NEW