ABCB1 p.Asp743Arg
| Predicted by SNAP2: | A: N (82%), C: N (72%), E: N (93%), F: D (63%), G: N (87%), H: N (66%), I: N (66%), K: N (87%), L: N (72%), M: N (66%), N: N (93%), P: N (78%), Q: N (87%), R: N (72%), S: N (93%), T: N (93%), V: N (78%), W: D (63%), Y: D (63%), |
| Predicted by PROVEAN: | A: N, C: D, E: N, F: D, G: N, H: N, I: D, K: N, L: D, M: N, N: N, P: N, Q: N, R: N, S: N, T: N, V: N, W: D, Y: D, |
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[hide] Coupled translocation events generate topological ... Mol Biol Cell. 1998 Sep;9(9):2681-97. Moss K, Helm A, Lu Y, Bragin A, Skach WR
Coupled translocation events generate topological heterogeneity at the endoplasmic reticulum membrane.
Mol Biol Cell. 1998 Sep;9(9):2681-97., [PMID:9725920]
Abstract [show]
Topogenic determinants that direct protein topology at the endoplasmic reticulum membrane usually function with high fidelity to establish a uniform topological orientation for any given polypeptide. Here we show, however, that through the coupling of sequential translocation events, native topogenic determinants are capable of generating two alternate transmembrane structures at the endoplasmic reticulum membrane. Using defined chimeric and epitope-tagged full-length proteins, we found that topogenic activities of two C-trans (type II) signal anchor sequences, encoded within the seventh and eighth transmembrane (TM) segments of human P-glycoprotein were directly coupled by an inefficient stop transfer (ST) sequence (TM7b) contained within the C-terminus half of TM7. Remarkably, these activities enabled TM7 to achieve both a single- and a double-spanning TM topology with nearly equal efficiency. In addition, ST and C-trans signal anchor activities encoded by TM8 were tightly linked to the weak ST activity, and hence topological fate, of TM7b. This interaction enabled TM8 to span the membrane in either a type I or a type II orientation. Pleiotropic structural features contributing to this unusual topogenic behavior included 1) a short, flexible peptide loop connecting TM7a and TM7b, 2) hydrophobic residues within TM7b, and 3) hydrophilic residues between TM7b and TM8.
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No. Sentence Comment
62 We then used the PCR overlap extension method to introduced mutations D743R/D744R.
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ABCB1 p.Asp743Arg 9725920:62:70
status: NEW73 D743R/ D744R and ⌬NGGLQP mutations were subsequently engineered into pSPMDR1-P by ligating HindIII-BstEII fragments from plasmids TM7a/b-8(DD/RR).P and TM7a/b-8.P (⌬NGGLQP), respectively, into HindIII-BstEII-digested pSPMDR1-P.
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ABCB1 p.Asp743Arg 9725920:73:0
status: NEW289 Effect of mutations D743R and D744R on TM7b ST activity and TM8 topology.
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ABCB1 p.Asp743Arg 9725920:289:20
status: NEW302 Moreover, each of these mutations (e.g., D743R/D744R, ⌬NGGLQP, and ⌬7b) also affected the stability and intracellular trafficking of full-length MDR1-Pgp protein in intact XOs (Bragin and Skach, unpublished observations), suggesting that structural features responsible for topological heterogeneity of MDR1-Pgp also contribute important information for protein maturation in cells.
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ABCB1 p.Asp743Arg 9725920:302:41
status: NEW[hide] Mode of binding of anti-P-glycoprotein antibody MR... J Biol Chem. 1998 Sep 25;273(39):25413-9. Vasudevan S, Tsuruo T, Rose DR
Mode of binding of anti-P-glycoprotein antibody MRK-16 to its antigen. A crystallographic and molecular modeling study.
J Biol Chem. 1998 Sep 25;273(39):25413-9., 1998-09-25 [PMID:9738009]
Abstract [show]
Monoclonal antibody MRK-16 recognizes a discontinuous extracellular epitope on the multidrug resistance-associated ATP-binding cassette transporter, P-glycoprotein. The atomic basis for specificity of this antibody is of interest because of its potential as a modulator of P-glycoprotein activity. The crystal structure of Fab MRK-16 is reported to a resolution of 2.8 A. A structure for a portion of the epitope was derived by comparison to regions of solved structures with similar primary sequence. This has permitted a proposal for the mode of binding of the peptide epitope to the antibody, in which the peptide makes specific contacts with complementarity-determining regions H1, H2, and H3 from the heavy chain and L3 from the light chain. These interactions are consistent with epitope mapping studies and with the observation that MRK-16 is specific for human class I P-glycoprotein. This result identifies side chains in MRK-16 that would be amenable to alteration in antibody engineering experiments to derive improved multidrug resistance inhibitors for clinical use during chemotherapy. In particular, Arg-H97 contacts both Glu-746 and Asp-744 of the peptide, Arg-L96 contacts Asp-743, and Thr-H33 interacts with Thr-747. All of these epitope residues were implicated in mediating specificity by epitope mapping studies.
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No. Sentence Comment
203 The proposed interaction of Asp-743 with Arg-L96 would explain the lack of tolerance of an alteration of position 743 to Thr or Gly.
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ABCB1 p.Asp743Arg 9738009:203:28
status: NEW