ABCMdb

ABCC1 p.Thr1242Ala

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PMID: 11429411 [PubMed] Zhang DW et al: "Identification of a nonconserved amino acid residue in multidrug resistance protein 1 important for determining substrate specificity: evidence for functional interaction between transmembrane helices 14 and 17."

No. Sentence Comment

11 As with mrp1, introduction of a second mutation based on the murine sequence to create MRP1E1089Q/ T1242A restored resistance to vincristine and VP-16, but not anthracyclines, without affecting transport of leukotriene C4 and E217betaG. Login to comment
66 To generate a MRP1E1089Q/T1242A double mutation, pGEM-MRP1-(2730-4832) containing mutation MRP1E1089Q was digested with StuI and XbaI to yield a 4.1-kilobase pair fragment comprised of nucleotides 2730-3758 of MRP1E1089Q attached to the vector fragment, and this fragment was then ligated to a 1.1-kilobase pair StuI-XbaI fragment encompassing nucleotides 3758-4832 of MRP1T1242A. Login to comment
134 Thus, Thr1242 was mutated to Ala, Cys, Ser, Leu, Lys, and Asp. Login to comment
137 After normalization for differences in expression levels, substitution of Thr1242 with Ala, Cys, Ser, Leu, and Lys decreased the ability of MRP1 to transport E217betaG by more than 2-fold relative to the wild type protein with no significant effect on LTC4 FIG. 2. Time course of ATP-dependent [3 H]LTC4 and [3 H]E217betaG uptake by membrane vesicles prepared from HEK293 stable transfectants expressing wild type mrp1 or A1239 mutant proteins. Login to comment
161 Consistent with the results obtained with the mrp1 mutant, substitution of Thr1242 with Ala in MRP1 decreased the normalized Vmax value for the mutant ϳ2-fold relative to wild type MRP1. Login to comment
167 In MRP1, substitution of Thr1242 with Ala increased the IC50 value from 15 to 134 ␮M. These results are independent of protein expression levels and provide strong evidence that the increase or decrease in E217betaG transport by mrp1A1239T and MRP1T1242A, respectively, is at least partially attributable to changes in the affinity of the proteins for this substrate. Login to comment
196 Consequently, a double mutation of MRP1 was also made, in which Glu1089 was replaced with Gln and Thr1242 was substituted with Ala (E1089Q/T1242A). Login to comment
228 Replacement of Thr1242 with Ala, Ser, Cys, Leu, and Lys decreased the ability of the protein to transport E217betaG 2-3-fold without significantly affecting LTC4 transport. Login to comment
234 The values shown represent the means Ϯ S.D. of relative resistance factors determined from 3-6 independent experiments. Resistance factors normalized for differences in the levels of mutant proteins expressed in the transfectant populations used are shown in parentheses. Transfectant Drug (relative resistance factor) Vincristine VP-16 Doxorubicin Epirubicin HEKMRP1 18.6 Ϯ 3.1 (18.6) 18.9 Ϯ 2.0 (18.9) 6.7 Ϯ 0.9 (6.7) 9.3 Ϯ 0.4 (9.3) n ϭ 6 n ϭ 6 n ϭ 6 n ϭ 6 HEKMRP1T1242A 14.5 Ϯ 0.9 (10.8) 13.6 Ϯ 1.2 (10.1) 2.6 Ϯ 0.2 (2.0) 3.2 Ϯ 0.3 (2.4) n ϭ 5 n ϭ 5 n ϭ 5 n ϭ 5 HEKMRP1T1242C 9.7 Ϯ 0.3 (9.7) 10.7 Ϯ 0.3 (10.7) 3.1 Ϯ 0.2 (3.1) 3.3 Ϯ 0.2 (3.3) n ϭ 3 n ϭ 3 n ϭ 3 n ϭ 3 HEKMRP1T1242S 9.1 Ϯ 0.5 (11.4) 9.6 Ϯ 0.7 (11.9) 2.5 Ϯ 0.5 (3.1) 2.6 Ϯ 0.4 (3.2) n ϭ 3 n ϭ 3 n ϭ 3 n ϭ 3 HEKMRP1T1242L 10.7 Ϯ 3.3 (11.9) 10.4 Ϯ 1.2 (10.7) 2.8 Ϯ 0.9 (2.9) 2.9 Ϯ 3.9 (3.0) n ϭ 3 n ϭ 3 n ϭ 3 n ϭ 3 HEKMRP1T1242D 6.5 Ϯ 1.2 (9.3) 7.0 Ϯ 0.5 (10.0) 2.3 Ϯ 0.2 (2.5) 2.4 Ϯ 0.1 (2.6) n ϭ 3 n ϭ 3 n ϭ 3 n ϭ 3 HEKMRP1T1242K 5.4 Ϯ 0.3 (11.5) 4.8 Ϯ 0.3 (12.0) 1.5 Ϯ 0.2 (3.7) 2.1 Ϯ 0.5 (4.1) n ϭ 3 n ϭ 3 n ϭ 3 n ϭ 3 HEKMRP1E1089Q/T1242A 18.3 Ϯ 5.3 (26.9) 17.8 Ϯ 1.5 (26.2) Ͻ1 Ͻ1 n ϭ 5 n ϭ 5 n ϭ 3 n ϭ 3 transport. Login to comment
252 In contrast, the IC50 for LTC4 transport by MRP1 T1242A was ϳ130 ␮M, a value similar to that obtained for wild type mrp1, while the IC50 of mrp1A1239T decreased to ϳ30 ␮M. It has been proposed that the transport of anionic/cationic substrates by MRP1 is facilitated by cationic/anionic acid residues present in the transmembrane helices (39). Login to comment
264 Transfectants tested were HEKmrp1 (f), HEKmrp1A1239T (Œ), and HEKmrp1Q1086E/A1239T (q) (C and D) and HEKMRP1 (Ⅺ), HEKMRP1T1242A (‚), and HEKMRP1E1089Q/T1242A (E) (E and F). Login to comment
268 Having found previously that mutation of Glu1089 in TM14 of MRP1 to Gln not only markedly reduced that ability of the protein to confer resistance to anthracyclines but also, to a lesser extent, to vincristine and VP-16 (29), we investigated the effect of combining this mutation, and the reciprocal mutation in the murine protein, with the A1239T and T1242A mutations of mrp1 and MRP1, respectively. Login to comment

PMID: 11925441 [PubMed] Zhang DW et al: "Determinants of the substrate specificity of multidrug resistance protein 1: role of amino acid residues with hydrogen bonding potential in predicted transmembrane helix 17."

No. Sentence Comment

136 In contrast, the T1242A mutation had no significant effect on LTC4 transport, and the effect of the Trp1246 mutations was relatively minor (a 2-fold increase in Km) (38, 39).2 To determine whether any of the other mutations in TM17 of MRP1 altered the efficiency with which the protein transported either LTC4 or E217betaG, we examined ATP-dependent uptake of these compounds by membrane vesicles prepared from HEK transfectants expressing each of these mutant proteins (Figs. Login to comment

PMID: 12138119 [PubMed] Qian YM et al: "Photolabeling of human and murine multidrug resistance protein 1 with the high affinity inhibitor [125I]LY475776 and azidophenacyl-[35S]glutathione."

No. Sentence Comment

164 In contrast, when the same preparations of HEK membranes were photolabeled with azidophenacyl-[35 S]GSH, the extent of labeling of T1242A MRP1 was higher than that of the wild type protein. Login to comment
230 Mutation of Thr-1242 to Ala, as found at the corresponding position in murine mrp1, decreases the ability to transport E217betaG and to confer drug resistance, but does not affect LTC4 transport. Login to comment

PMID: 14754409 [PubMed] Karwatsky JM et al: "Drug binding domains of MRP1 (ABCC1) as revealed by photoaffinity labeling."

No. Sentence Comment

233 A mutation of Thr1242 to Ala in MRP1 decreases photoaffinity labeling with [125 I]LY475776 and supports the possibility of a drug binding site in TM 17 of MRP1. Login to comment

PMID: 17295059 [PubMed] Chang XB et al: "A molecular understanding of ATP-dependent solute transport by multidrug resistance-associated protein MRP1."

No. Sentence Comment

117 Many mutations in TM17, such as Y1236F, T1241A, T1242A, T1242C, T1242S, T1242L, Y1243F, N1245A, W1246C, W1246A, W1246F, W1246Y, or R1249K, significantly affect MRP1 function [83-86]. Login to comment
146 Introduction of a second mutation based on mouse Mrp1 sequence into human MRP1/T1242A to generate a double mutant MRP1/ E1089Q/T1242A created a protein similar to mouse wild-type Mrp1 that restored resistance to vicristine and VP-16 but not to doxorubicin and epirubicin [85]. Login to comment

PMID: 19949927 [PubMed] Chang XB et al: "Molecular mechanism of ATP-dependent solute transport by multidrug resistance-associated protein 1."

No. Sentence Comment

104 Mutations of C43S in TM1 (112); P343A, K332L and K332D in TM6 (113, 114); W445A and P448A in TM8 (113, 115); T550A, T556A and P557A in TM10 (113, 116); N590A, F594A, P595A, N597A, S604A and S605A in TM11 (113, 117, 118); E1089Q, E1089A, E1089L, E1089N, K1092, S1097 and N1100 in TM14 (119, 120); R1197K in TM16 (121); Y1236F, T1241A, T1242A, T1242C, T1242S, T1242L, Y1243F, N1245A, W1246C, W1246A, W1246F, W1246Y or R1249K in TM17 (121-124) significantly affect MRP1 function. Login to comment