ABCB1 p.Glu256Ala
| Predicted by SNAP2: | A: D (80%), C: D (71%), D: D (85%), F: D (91%), G: D (91%), H: D (91%), I: D (91%), K: D (91%), L: D (91%), M: D (85%), N: D (91%), P: D (91%), Q: D (75%), R: D (91%), S: D (91%), T: D (91%), V: D (91%), W: D (91%), Y: D (91%), |
| Predicted by PROVEAN: | A: D, C: D, D: D, F: 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] A salt bridge in intracellular loop 2 is essential... Biochemistry. 2013 May 14;52(19):3194-6. doi: 10.1021/bi400425k. Epub 2013 May 3. Loo TW, Clarke DM
A salt bridge in intracellular loop 2 is essential for folding of human p-glycoprotein.
Biochemistry. 2013 May 14;52(19):3194-6. doi: 10.1021/bi400425k. Epub 2013 May 3., [PMID:23634976]
Abstract [show]
There is no high-resolution structure of the human P-glycoprotein (P-gp, ABCB1) drug pump. Homology models based on the crystal structures of mouse and Caenorhabditis elegans P-gps show extensive contacts between intracellular loop 2 (ICL2, in the first transmembrane domain) and the second nucleotide-binding domain. Human P-gp modeled on these P-gp structures yields different ICL2 structures. Only the model based on the C. elegans P-gp structure predicts the presence of a salt bridge. We show that the Glu256-Arg276 salt bridge was critical for P-gp folding.
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No. Sentence Comment
27 By contrast, none of the Gly mutations in ICL1, -3, or -4 inhibited maturation.10 To test if the charged amino acids Glu256 and Arg276 were important for maturation, we characterized mutants E256A and R276A.
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ABCB1 p.Glu256Ala 23634976:27:191
status: NEW28 Figure 1E shows that E256A or R276A mutations inhibited maturation.
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ABCB1 p.Glu256Ala 23634976:28:21
status: NEW29 While the mature 170 kDa protein was the major product of wild-type P-gp, the immature 150 kDa protein was the major product of mutants E256A and R276A.
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ABCB1 p.Glu256Ala 23634976:29:136
status: NEW31 It was found that the E255A, K271A, K272A, E273A, and E275A mutants were different from the E256A and R276A mutants because they yielded mature 170 kDa P-gp as their major product (Figure 1E).
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ABCB1 p.Glu256Ala 23634976:31:92
status: NEW44 To address this question, we first tested whether it was possible to promote maturation of the E256A or R276A mutant.
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ABCB1 p.Glu256Ala 23634976:44:95
status: NEW45 We previously showed that P-gp was inactive when it was trapped in the ER as a core-glycosylated intermediate.16 Drug substrates (e.g., cyclosporine A) can promote maturation of P-gp processing mutants.17 Mutants E256A and R276A were expressed in HEK293 cells in the presence or absence of 10 bc;M cyclosporine A.
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ABCB1 p.Glu256Ala 23634976:45:213
status: NEW48 The putative Glu256-Arg276 salt bridge was not essential for activity as both the E256A and R276A mutants showed wild-type verapamil-stimulated ATPase activity (Figure S1B of the Supporting Information).
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ABCB1 p.Glu256Ala 23634976:48:82
status: NEW