ABCB1 p.Arg262Ala
| Predicted by SNAP2: | A: D (85%), C: D (85%), D: D (95%), E: D (91%), F: D (91%), G: D (91%), H: D (85%), I: D (91%), K: D (71%), L: D (91%), M: D (85%), N: D (85%), P: D (91%), Q: D (80%), S: D (85%), T: D (85%), V: D (91%), W: D (91%), Y: D (91%), |
| Predicted by PROVEAN: | A: D, C: D, D: D, E: D, F: D, G: D, H: D, I: D, K: N, L: D, M: D, N: D, P: D, Q: 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
98 Mutants A260L, R262A, T263A, I265S, and Q270A yielded a mixture of mature and immature P-gp (Fig. 1, B and C).
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ABCB1 p.Arg262Ala 23733192:98:15
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
152 Asymmetry of the P-gp Drug Pump Transmission Interfaces JULY 3, 2015ߦVOLUME 290ߦNUMBER 27 JOURNAL OF BIOLOGICAL CHEMISTRY 16957 at SEMMELWEIS UNIV OF MEDICINE on December 4, twenty-eight mutations in ICL2 (A250L, G251V, V253S, A254L, E256A, L258S, I261S, V264S, F267A, G268V, G269V, L274S, R276A, Y277A) inhibited maturation of P-gp (b0d;15% mature P-gp) while four other ICL2 mutations (A2650L, R262A, T263A, and I265S) partially reduced maturation of P-gp (about 55-60% mature P-gp).
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ABCB1 p.Arg262Ala 25987565:152:412
status: NEW252 We constructed histidine-tagged R262A/R905A and T263A/ T906A mutants (in wild-type background) to test if mutations in both IH2 and IH4 were needed to inactivate P-gp ATPase activity.
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ABCB1 p.Arg262Ala 25987565:252:32
status: NEW293 The observation that P-gp mutants R262A/ R905A, T263A/T906A (this study), and D164C/D805C (51) retain substantial activity suggests that there are multiple NBD-TMD contacts as reported by Jin et al. (21).
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ABCB1 p.Arg262Ala 25987565:293:34
status: NEW