ABCB1 p.Ala295Cys
| Predicted by SNAP2: | C: N (53%), D: D (66%), E: D (59%), F: N (53%), G: N (61%), H: N (66%), I: N (61%), K: N (61%), L: N (66%), M: N (66%), N: N (66%), P: D (71%), Q: N (66%), R: N (53%), S: N (87%), T: N (87%), V: N (57%), W: D (71%), Y: D (63%), |
| Predicted by PROVEAN: | C: D, D: D, E: D, F: D, G: D, H: D, I: D, K: D, L: D, M: D, N: D, P: D, Q: D, R: D, S: N, T: N, V: N, W: D, Y: D, |
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[hide] The packing of the transmembrane segments of human... J Biol Chem. 2000 Feb 25;275(8):5253-6. Loo TW, Clarke DM
The packing of the transmembrane segments of human multidrug resistance P-glycoprotein is revealed by disulfide cross-linking analysis.
J Biol Chem. 2000 Feb 25;275(8):5253-6., 2000-02-25 [PMID:10681495]
Abstract [show]
Residues from several transmembrane (TM) segments of P-glycoprotein (P-gp) likely form the drug-binding site(s). To determine the organization of the TM segments, pairs of cysteine residues were introduced into the predicted TM segments of a Cys-less P-gp, and the mutant protein was subjected to oxidative cross-linking. In SDS gels, the cross-linked product migrated with a slower mobility than the native protein. The cross-linked products were not detected in the presence of dithiothreitol. Cross-linking was observed in 12 of 125 mutants. The pattern of cross-linking suggested that TM6 is close to TMs 10, 11, and 12, while TM12 is close to TMs 4, 5, and 6. In some mutants the presence of drug substrate colchicine, verapamil, cyclosporin A, or vinblastine either enhanced or inhibited cross-linking. Cross-linking was inhibited in the presence of ATP plus vanadate. These results suggest that the TM segments critical for drug binding must be close to each other and exhibit different conformational changes in response to binding of drug substrate or vanadate trapping of nucleotide. Based on these results, we propose a model for the arrangement of the TM segments.
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No. Sentence Comment
65 Twelve of the 125 P-gp mutants (TM4/TM12 constructs L227C/S993C, V231C/S993C, W232C/S993C, A233C/S993C, I235C/S993C, and L236C/S993C; TM5/TM12 constructs A295C/S993C and I299C/S993C; TM10/TM6 constructs V874C/P350C, E875C/ P350C, and M876C/P350C; and TM11/TM6 construct G939C/ P350C), however, had slower mobilities in SDS-PAGE after treatment with oxidant.
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ABCB1 p.Ala295Cys 10681495:65:154
status: NEW77 In these cross-linking experiments, the amount of oxidant was lowered by 10-fold (0.2 mM), and the minimum temperature required to induce cross-TABLE I Cross-linking analysis of P-gp Cross-linking of S993C (TM12) with residues in the following TM: TM1 TM2 TM3 TM4 TM5 M51C -a Y130C - G185C - G226C - I293C - V52C - I131C - I186C - L227C ϩb T294C - V53C - Q132C - G187C - S228C - A295C ϩ G54C - V133C - D188C - A229C - N296C - T55C - S134C - K189C - A230C - I297C - L56C - F135C - I190C - V231C ϩ S298C - A57C - W136C - G191C - W232C ϩ I299C ϩ A58C - C137C - M192C - A233C ϩ G300C - I59C - L138C - F193C - K234C - A301C - I60C - A139C - F194C - I235C ϩ A302C - H61C - A140C - Q195C - L236C ϩ F303C - G141C - S196C - S237C - L304C - Cross-linking of P350C (TM6) with residues in the following TM: TM7 TM8 TM9 TM10 TM11 F711C - F770C - A828C - I867C - A935C - V712C - F771C - I829C - I868C - H936C - V713C - L772C - G830C - A869C - I937C - G714C - Q773C - S831C - I870C - F938C - V715C - G774C - R832C - A871C - G939C ϩ F716C - F775C - L833C - G872C - I940C - C717C - T776C - A834C - V873C - T941C - A718C - F777C - V835C - V874C ϩ F942C - I719C - G778C - I836C - E875C ϩ S943C - I720C - K779C - T837C - M876C ϩ F944C - N721C - A780C - Q838C - K877C - T945C - G722C - G781C - N839C - M878C - Q946C - G723C - E782C - I840C - L879C - A947C - I783C - a -, no cross-linked product detected in SDS-PAGE. b ϩ, cross-linked product detected in SDS-PAGE.
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ABCB1 p.Ala295Cys 10681495:77:385
status: NEW99 Mutants L227C/S993C, V231C/ S993C, W232C/S993C, A233C/S993C, I235C/S993C, L236C/ S993C, A295C/S993C, I299C/S993C, V874C/P350C, E875C/ P350C, M876C/P350C, and G939C/P350C were inhibited by 81, 88, 90, 89, 93, 81, 78, 87, 87, 77, 70, and 78%, respectively.
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ABCB1 p.Ala295Cys 10681495:99:88
status: NEW118 TABLE II Minimum temperature required for cross-linking Residues TM segments 4 °C 21 °C 37 °C L227C/S993C 4/12 -a - ϩ V231C/S993C 4/12 - ϩ ϩ W232C/S993C 4/12 - ϩ ϩ A233C/S993C 4/12 ϩb ϩ ϩ I235C/S993C 4/12 ϩ ϩ ϩ L236C/S993C 4/12 ϩ ϩ ϩ A295C/S993C 5/12 - ϩ ϩ I299C/S993C 5/12 ϩ ϩ ϩ V874C/P350C 10/6 - ϩ ϩ E875C/P350C 10/6 - - ϩ M876C/P350C 10/6 - ϩ ϩ G939C/P350C 11/6 - ϩ ϩ a -, no cross-linked product detected in SDS-PAGE. b ϩ, cross-linked product detected in SDS-PAGE.
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ABCB1 p.Ala295Cys 10681495:118:333
status: NEW[hide] Disulfide cross-linking analysis shows that transm... J Biol Chem. 2004 Feb 27;279(9):7692-7. Epub 2003 Dec 10. Loo TW, Bartlett MC, Clarke DM
Disulfide cross-linking analysis shows that transmembrane segments 5 and 8 of human P-glycoprotein are close together on the cytoplasmic side of the membrane.
J Biol Chem. 2004 Feb 27;279(9):7692-7. Epub 2003 Dec 10., 2004-02-27 [PMID:14670948]
Abstract [show]
Human P-glycoprotein (P-gp) transports a wide variety of structurally diverse compounds out of the cell. Knowledge about the packing of the transmembrane (TM) segments is essential for understanding the mechanism of drug recognition and transport. We used cysteine-scanning mutagenesis and disulfide cross-linking analysis to determine which TM segment in the COOH half of P-gp was close to TMs 5 and 6 since these segments in the NH(2) half are important for drug binding. An active Cys-less P-gp mutant cDNA was used to generate 240 double cysteine mutants that contained 1 cysteine in TMs 5 or 6 and another in TMs 7 or 8. The mutants were subjected to oxidative cross-linking analysis. No disulfide cross-linking was observed in the 140 TM6/TM7 or TM6/TM8 mutants. By contrast, cross-linking was detected in several P-gp TM5/TM8 mutants. At 4 degrees C, when thermal motion is low, P-gp mutants N296C(TM5)/G774C(TM8), I299C(TM5)/F770C(TM8), I299C(TM5)/G774C(TM8), and G300C(TM5)/F770C(TM8) showed extensive cross-linking with oxidant. These mutants retained drug-stimulated ATPase activity, but their activities were inhibited after treatment with oxidant. Similarly, disulfide cross-linking was inhibited by vanadate trapping of nucleotide. These results indicate that significant conformational changes must occur between TMs 5 and 8 during ATP hydrolysis. We revised the rotational symmetry model for TM packing based on our results and by comparison to the crystal structure of MsbA (Chang, G. (2003) J. Mol. Biol. 330, 419-430) such that TM5 is adjacent to TM8, TM2 is adjacent to TM11, and TMs 1 and 7 are next to TMs 6 and 12, respectively.
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No. Sentence Comment
105 Six mutants (A295C/ G774C, N296C/F771C, N296C/Q773C, N296C/F775C, I297C/ F770C, and G300C/F775C) showed relatively weak (Ͻ50%) cross-linking (Table I).
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ABCB1 p.Ala295Cys 14670948:105:13
status: NEW124 The verapamiland demecolcine-stimulated ATPase activities rel- TABLE I Cross-linking between residues in TMs 5 and 8 TM5 TM 8 F767C I768C T769C F770C F771C L772C Q773C G774C F775C T776C I293C -a - - - - - - - ϩϩb - T294C - - - - - - - - - - A295C - - - - - - - ϩ - - N296C - - - ϩϩb ϩ - ϩ ϩϩc ϩ - I297C - - - ϩd ϩϩ - - ϩϩb - - S298C - - - - - - - - - - I299C - - - ϩϩc - - - ϩϩc - - G300C ϩϩe - - ϩϩc ϩϩb - - ϩϩb ϩ - A301C - - - - - - - - - - A302C - - - - - - - - - - a No cross-linked product detected in SDS-PAGE gels at 37 °C. b Cross-linked product was also detected at 22 °C. c Cross-linked product was also detected at 22 °C and at 4 °C. d Relatively weak cross-linking (Ͻ50% of P-gp cross-linked) at 37 °C. e Relatively strong cross-linking (Ͼ50% of P-gp cross-linked) at 37 °C. FIG. 2.
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ABCB1 p.Ala295Cys 14670948:124:253
status: NEW[hide] Identification of the distance between the homolog... J Biol Chem. 2014 Mar 21;289(12):8484-92. doi: 10.1074/jbc.M114.552075. Epub 2014 Feb 12. Loo TW, Clarke DM
Identification of the distance between the homologous halves of P-glycoprotein that triggers the high/low ATPase activity switch.
J Biol Chem. 2014 Mar 21;289(12):8484-92. doi: 10.1074/jbc.M114.552075. Epub 2014 Feb 12., [PMID:24523403]
Abstract [show]
P-glycoprotein (P-gp, ABCB1) is an ATP-binding cassette drug pump that protects us from toxic compounds and confers multidrug resistance. Each homologous half contains a transmembrane domain with six transmembrane segments followed by a nucleotide-binding domain (NBD). The drug- and ATP-binding sites reside at the interface between the transmembrane domain and NBDs, respectively. Drug binding activates ATPase activity by an unknown mechanism. There is no high resolution structure of human P-gp, but homology models based on the crystal structures of bacterial, mouse, and Caenorhabditis elegans ATP-binding cassette drug pumps yield both open (NBDs apart) and closed (NBDs together) conformations. Molecular dynamics simulations predict that the NBDs can be separated over a range of distances (over 20 A). To determine the distance that show high or low ATPase activity, we cross-linked reporter cysteines L175C (N-half) and N820C (C-half) with cross-linkers of various lengths that separated the halves between 6 and 30 A (alpha-carbons). We observed that ATPase activity increased over 10-fold when the cysteines were cross-linked at distances between 6 and 19 A, although cross-linking at distances greater than 20 A yielded basal levels of activity. The results suggest that the ATPase activation switch appears to be turned on or off when L175C/N820 are clamped at distances less than or greater than 20 A, respectively. We predict that the high/low ATPase activity switch may occur at a distance where the NBDs are predicted in molecular dynamic simulations to undergo pronounced twisting as they approach each other (Wise, J. G. (2012) Biochemistry 51, 5125-5141).
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No. Sentence Comment
207 The P-gp molecular dynamics simulation study (64) may also provide an explanation for the inhibition of ATPase activity previously observed when cysteines A295C (in IH2 that connects TM segments 4 and 5) and W803C (in IH3 that connects TM segments 9 and 10) were directly cross-linked (49).
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ABCB1 p.Ala295Cys 24523403:207:155
status: NEW209 It is possible that direct cross-linking of A295C (in IH2 that connects TM segments 4 and 5) to W803C in IH3 would interfere with straightening of TM segments 4 and 5 to trap P-gp in an inactive conformation.
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ABCB1 p.Ala295Cys 24523403:209:44
status: NEW