ABCB1 p.Ala128Cys
| Predicted by SNAP2: | C: N (82%), D: D (75%), E: D (59%), F: N (78%), G: N (61%), H: D (53%), I: N (72%), K: D (63%), L: N (87%), M: N (78%), N: D (53%), P: D (66%), Q: N (57%), R: D (53%), S: N (82%), T: N (87%), V: N (87%), W: D (80%), Y: D (63%), |
| Predicted by PROVEAN: | C: N, D: D, E: D, F: N, G: D, H: D, I: N, K: D, L: N, M: N, N: D, P: D, Q: D, R: D, S: N, T: N, V: N, W: D, Y: N, |
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[hide] Val133 and Cys137 in transmembrane segment 2 are c... J Biol Chem. 2004 Apr 30;279(18):18232-8. Epub 2004 Jan 28. Loo TW, Bartlett MC, Clarke DM
Val133 and Cys137 in transmembrane segment 2 are close to Arg935 and Gly939 in transmembrane segment 11 of human P-glycoprotein.
J Biol Chem. 2004 Apr 30;279(18):18232-8. Epub 2004 Jan 28., 2004-04-30 [PMID:14749322]
Abstract [show]
P-glycoprotein (P-gp; ABCB1) transports a wide variety of structurally diverse compounds out of the cell. The protein has two homologous halves joined by a linker region. Each half consists of a transmembrane (TM) domain with six TM segments and a nucleotide-binding domain. The drug substrate-binding pocket is at the interface between the TM segments in each half of the protein. Preliminary studies suggested that the arrangement of the two halves of P-gp shows rotational symmetry (i.e. "head-to-tail" arrangement). Here, we tested this model by determining whether the cytoplasmic ends of TM2 and TM3 in the N-terminal half are in close contact with TM11 in the C-terminal half. Mutants containing a pair of cysteines in TM2/TM11 or TM3/TM11 were subjected to oxidative cross-linking with copper phenanthroline. Two of the 110 TM2/TM11 mutants, V133C(TM2)/G939C(TM11) and C137C(TM2)/A935C (TM11), were cross-linked at 4 degrees C, when thermal motion is reduced. Cross-linking was specific since no cross-linked product was detected in the 100 double Cys TM3/TM11 mutants. Vanadate trapping of nucleotide or the presence of some drug substrates inhibited cross-linking of mutants V133C(TM2)/G939C(TM11) and C137C(TM2)/A935C(TM11). Cross-linking of TM2 and TM11 also blocked drug-stimulated ATPase activity. The close proximity of TM2/TM11 and TM5/TM8 (Loo, T. W., Bartlett, M. C., and Clarke, D. M. (2004) J. Biol. Chem. 279, 7692-7697) indicates that these regions between the two halves must enclose the drug-binding pocket at the cytoplasmic side of P-gp. They may form the "hinges" required for conformational changes during the transport cycle.
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None has been submitted yet.
No. Sentence Comment
124 TABLE I Cross-linking between residues in TM2 and TM11 -, no cross-linked product detected on SDS-polyacrylamide gels at 37 °C; ϩ, relatively weak cross-linking (Ͻ50% of P-gp cross-linked) at 37 °C; ϩϩ, relatively strong cross-linking (Ͼ50% of P-gp cross-linked) at 37 °C; *, cross-linked product also detected at 22 °C; **, cross-linked product also detected at 22 and 4 °C. TM2 TM11 A935C H936C I937C F938C G939C I940C T941C F942C S943C F944C A128C - - - - - - - - - - A129C - - - - - - - - - - Y130C - - - - ϩ ϩ - ϩ ϩ - I131C - - - - - - - - - - Q132C - - - - - - - - - - V133C - - - ϩ ϩϩ, ** - - ϩ ϩ - S134C ϩ ϩ - - ϩ ϩ - - - - F135C - - - - - - - - - - W136C - - - - - - - - - - C137C ϩϩ, ** - - - ϩ - - - - - L138C ϩϩ, * - - - - - - - - - TM11 are close to each other at their cytoplasmic ends.
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ABCB1 p.Ala128Cys 14749322:124:500
status: NEW