ABCB1 p.Phe1086Arg
| Predicted by SNAP2: | A: D (75%), C: D (59%), D: D (91%), E: D (85%), G: D (80%), H: D (80%), I: D (71%), K: D (91%), L: D (59%), M: D (59%), N: D (80%), P: D (85%), Q: D (71%), R: D (85%), S: D (71%), T: D (75%), V: D (71%), W: D (59%), Y: N (53%), |
| Predicted by PROVEAN: | A: D, C: D, D: D, E: D, G: D, H: D, I: D, K: D, L: D, M: D, N: D, P: D, Q: D, R: D, S: D, T: D, V: D, W: D, Y: D, |
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[hide] Human P-glycoprotein contains a greasy ball-and-so... J Biol Chem. 2013 Jul 12;288(28):20326-33. doi: 10.1074/jbc.M113.484550. Epub 2013 Jun 3. Loo TW, Bartlett MC, Clarke DM
Human P-glycoprotein contains a greasy ball-and-socket joint at the second transmission interface.
J Biol Chem. 2013 Jul 12;288(28):20326-33. doi: 10.1074/jbc.M113.484550. Epub 2013 Jun 3., [PMID:23733192]
Abstract [show]
The P-glycoprotein drug pump protects us from toxins. Drug-binding sites in the transmembrane (TM) domains (TMDs) are connected to the nucleotide-binding domains (NBDs) by intracellular helices (IHs). TMD-NBD cross-talk is a key step in the transport mechanism because drug binding stimulates ATP hydrolysis followed by drug efflux. Here, we tested whether the IHs are critical for maturation and TMD-NBD coupling by characterizing the effects of mutations to the IH1 and IH2 interfaces. Although IH1 mutations had little effect, most mutations at the IH2-NBD2 interface inhibited maturation or activity. For example, the F1086A mutation at the IH2-NBD2 interface abolished drug-stimulated ATPase activity. The mutant F1086A, however, retained the ability to bind ATP and drug substrates. The mutant was defective in mediating ATP-dependent conformational changes in the TMDs because binding of ATP no longer promoted cross-linking between cysteines located at the extracellular ends of TM segments 6 and 12. Replacement of Phe-1086 (in NBD2) with hydrophobic but not charged residues yielded active mutants. The activity of the F1086A mutant could be restored when the nearby residue Ala-266 (in IH2) was replaced with aromatic residues. These results suggest that Ala-266/Phe-1086 lies in a hydrophobic IH2-NBD2 "ball-and-socket" joint.
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No. Sentence Comment
175 Fig. 5A shows that the F1086D or F1086R mutations inhibited maturation of P-gp.
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ABCB1 p.Phe1086Arg 23733192:175:33
status: NEW177 Mutants F1086D and F1086R could still be rescued if they were expressed in the presence of a drug substrate (Fig. 5B).
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ABCB1 p.Phe1086Arg 23733192:177:19
status: NEW179 Mutants F1086D and F1086R were first expressed in the presence of cyclosporine A to promote maturation before isolating the histidine-tagged protein.
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ABCB1 p.Phe1086Arg 23733192:179:19
status: NEW212 A, F1086X mutants were expressed in the absence of drug substrates. B, processing mutants F1086D and F1086R were expressed in the presence (af9;) or absence (afa;) of cyclosporine A (Cyclo), and whole cell SDS extracts were subjected to immunoblot analysis.
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ABCB1 p.Phe1086Arg 23733192:212:101
status: NEW214 Histidine-tagged mutants F1086D and F1086R were first expressed in the presence of cyclosporine A to promote maturation of P-gp before isolation of the protein by nickel-chelate chromatography. Each value is the mean afe; S.D. (n afd; 3).
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ABCB1 p.Phe1086Arg 23733192:214:36
status: NEW[hide] The Transmission Interfaces Contribute Asymmetrica... J Biol Chem. 2015 Jul 3;290(27):16954-63. doi: 10.1074/jbc.M115.652602. Epub 2015 May 18. Loo TW, Clarke DM
The Transmission Interfaces Contribute Asymmetrically to the Assembly and Activity of Human P-glycoprotein.
J Biol Chem. 2015 Jul 3;290(27):16954-63. doi: 10.1074/jbc.M115.652602. Epub 2015 May 18., [PMID:25987565]
Abstract [show]
P-glycoprotein (P-gp; ABCB1) is an ABC drug pump that protects us from toxic compounds. It is clinically important because it confers multidrug resistance. The homologous halves of P-gp each contain a transmembrane (TM) domain (TMD) with 6 TM segments followed by a nucleotide-binding domain (NBD). The drug- and ATP-binding sites reside at the interface between the TMDs and NBDs, respectively. Each NBD is connected to the TMDs by a transmission interface involving a pair of intracellular loops (ICLs) that form ball-and-socket joints. P-gp is different from CFTR (ABCC7) in that deleting NBD2 causes misprocessing of only P-gp. Therefore, NBD2 might be critical for stabilizing ICLs 2 and 3 that form a tetrahelix bundle at the NBD2 interface. Here we report that the NBD1 and NBD2 transmission interfaces in P-gp are asymmetric. Point mutations to 25 of 60 ICL2/ICL3 residues at the NBD2 transmission interface severely reduced P-gp assembly while changes to the equivalent residues in ICL1/ICL4 at the NBD1 interface had little effect. The hydrophobic nature at the transmission interfaces was also different. Mutation of Phe-1086 or Tyr-1087 to arginine at the NBD2 socket blocked activity or assembly while the equivalent mutations at the NBD1 socket had only modest effects. The results suggest that the NBD transmission interfaces are asymmetric. In contrast to the ICL2/3-NBD2 interface, the ICL1/4-NBD1 transmission interface is more hydrophilic and insensitive to mutations. Therefore the ICL2/3-NBD2 transmission interface forms a precise hydrophobic connection that acts as a linchpin for assembly and trafficking of P-gp.
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No. Sentence Comment
15 Mutation of Phe-1086 or Tyr-1087 to arginine at the NBD2 socket blocked activity or assembly while the equivalent mutations at the NBD1 socket had only modest effects.
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ABCB1 p.Phe1086Arg 25987565:15:12
status: NEW178 Mutants F1086A, F1086L, and F1086W yielded mature 170 kDa protein as the major product, whereas F1086R yielded little mature P-gp (b0d;5%) (Fig. 4A).
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ABCB1 p.Phe1086Arg 25987565:178:96
status: NEW185 While the F1086A and F1086R mutations FIGURE 3.
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ABCB1 p.Phe1086Arg 25987565:185:21
status: NEW276 The F1086R or Y1087R mutations at the NBD2 socket blocked maturation and activity while P-gp showed substantial activity when the comparable mutations (L443R, Y444R) were made to the NBD1 socket.
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ABCB1 p.Phe1086Arg 25987565:276:4
status: NEW