ABCC1 p.Arg1202Leu
Predicted by SNAP2: | A: D (85%), C: D (85%), D: D (95%), E: D (91%), F: D (91%), G: D (85%), H: D (66%), I: D (80%), K: D (85%), L: D (85%), M: D (85%), N: D (71%), P: D (95%), Q: D (85%), S: D (85%), T: D (80%), V: D (85%), W: D (85%), Y: D (85%), |
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] Mutational analysis of ionizable residues proximal... J Biol Chem. 2004 Sep 10;279(37):38871-80. Epub 2004 Jun 18. Situ D, Haimeur A, Conseil G, Sparks KE, Zhang D, Deeley RG, Cole SP
Mutational analysis of ionizable residues proximal to the cytoplasmic interface of membrane spanning domain 3 of the multidrug resistance protein, MRP1 (ABCC1): glutamate 1204 is important for both the expression and catalytic activity of the transporter.
J Biol Chem. 2004 Sep 10;279(37):38871-80. Epub 2004 Jun 18., 2004-09-10 [PMID:15208328]
Abstract [show]
The multidrug resistance protein MRP1 is an ATP-dependent transporter of organic anions and chemotherapeutic agents. A significant number of ionizable amino acids are found in or proximal to the 17 transmembrane (TM) helices of MRP1, and we have investigated 6 of these at the cytoplasmic interface of TM13-17 for their role in MRP1 expression and transport activity. Opposite charge substitutions of TM13 Arg(1046) and TM15 Arg(1131) did not alter MRP1 expression nor did they substantially affect activity. In contrast, opposite charge substitutions of TM16 Arg(1202) and Glu(1204) reduced protein expression by >80%; however, MRP1 expression was not affected when Arg(1202) and Glu(1204) were replaced with neutral or same-charge residues. In addition, organic anion transport levels of the R1202L, R1202G, and R1202K mutants were comparable with wild-type MRP1. In contrast, organic anion transport by E1204L was substantially reduced, whereas transport by E1204D was comparable with wild-type MRP1, with the notable exception of GSH. Opposite charge substitutions of TM16 Arg(1197) and TM17 Arg(1249) did not affect MRP1 expression but substantially reduced transport. Mutants containing like-charge substitutions of Arg(1197) or Arg(1249) were also transport-inactive and no longer bound leukotriene C(4). In contrast, substrate binding by the transport-compromised E1204L mutant remained intact. Furthermore, vanadate-induced trapping of azido-ADP by E1204L was dramatically increased, indicating that this mutation may cause a partial uncoupling of the catalytic and transport activities of MRP1. Thus, Glu(1204) serves a dual role in membrane expression of MRP1 and a step in its catalytic cycle subsequent to initial substrate binding.
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No. Sentence Comment
4 In addition, organic anion transport levels of the R1202L, R1202G, and R1202K mutants were comparable with wild-type MRP1.
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ABCC1 p.Arg1202Leu 15208328:4:51
status: NEW116 MRP1 expression levels in membrane vesicle proteins R1202G and R1202L prepared from cells expressing the neutrally substituted Arg1202 mutants were determined as described in A.
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ABCC1 p.Arg1202Leu 15208328:116:63
status: NEW118 Immunoblots of membrane vesicle proteins prepared from cells expressing the Glu1204 mutants E1204L and E1204D were carried out as described in A. TABLE I Summary of organic anion transport activity of MRP1 mutants with substitutions of ionizable amino acids in and proximal to TM13 to TM17 of MSD3 Mutation % Wild-type MRP1 transport activitya E217betaG LTC4 E1SO4 MTX GSH TM13 R1046D 115 70 80 120 NDb TM14 D1084R Ͻ10 Ͻ10 15 25 Ͻ10 D1084E 80 20 65 90 20 TM15 R1131E 70 50 80 60 ND TM16 R1197E Ͻ10 Ͻ10 Ͻ15 Ͻ10 ND R1197K 20 Ͻ25 Ͻ20 Ͻ10 ND R1202G 115 115 75 70 ND R1202L 115 120 50 110 ND E1204L Ͻ10 50 10 110 Ͻ25 E1204D 100 115 100 115 Ͻ25 TM17 R1249D Ͻ10 Ͻ15 Ͻ10 Ͻ10 ND R1249K Ͻ10 10 Ͻ15 Ͻ10 ND a The values shown are means of duplicate or triplicate determinations and are derived from Fig. 2, 4, and 5 (see figure legends for details).
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ABCC1 p.Arg1202Leu 15208328:118:622
status: NEW124 Immunoblots showed that expression levels of the R1202G and R1202L mutants (Fig. 3B) and the E1204L and E1204D mutants (Fig. 3C) ranged from 80 to 225% of wild-type MRP1.
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ABCC1 p.Arg1202Leu 15208328:124:60
status: NEW127 At 1 min, E217betaG and LTC4 uptake by the R1202G and R1202L mutants was comparable with wild-type levels (Fig. 4, A and B).
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ABCC1 p.Arg1202Leu 15208328:127:54
status: NEW128 Levels of E1SO4 uptake by the R1202G mutant were reduced by ϳ25%, whereas uptake by the R1202L mutant was reduced by ϳ50% (Fig. 4C).
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ABCC1 p.Arg1202Leu 15208328:128:94
status: NEW129 Uptake levels of MTX by the R1202G mutant was moderately reduced (by ϳ30%), whereas uptake by R1202L was comparable with wild-type MRP1 (Fig. 4D).
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ABCC1 p.Arg1202Leu 15208328:129:100
status: NEW169 A-D, uptake of 3 H-labeled organic anions by the membrane vesicles shown in Fig. 3B which were prepared from cells transfected with empty pcDNA3.1 vector (open bars), and vector containing wild-type MRP1 cDNA (black bars), and the neutrally substituted Arg1202 mutant R1202G and R1202L cDNAs (gray bars).
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ABCC1 p.Arg1202Leu 15208328:169:279
status: NEW201 In addition to being readily expressed, the neutrally substituted mutants of TM16 Arg1202 (R1202G and R1202L) exhibited transport activities that were, in the case of most substrates, similar to those of wild-type MRP1.
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ABCC1 p.Arg1202Leu 15208328:201:102
status: NEW