ABCMdb

ABCC1 p.Asn1245Ala

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Publications

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

2 To determine whether other residues with hydrogen bonding potential within TM17 influence substrate specificity, we replaced Ser1233 , Ser1235 , Ser1237 , Gln1239 , Thr1241 , and Asn1245 with Ala and Tyr1236 and Tyr1243 with Phe. Login to comment
6 Replacement of Asn1245 with Ala also decreased resistance to VP-16, doxorubicin, and epirubicin but increased resistance to vincristine. Login to comment
50 We have systematically mutated the amino acids Ser1233 , Ser1235 , Ser1237 , Gln1239 , Thr1241 , and Asn1245 to alanine and each of two tyrosines, Tyr1236 and Tyr1243 , to Phe. Login to comment
104 To examine their possible importance in determining the substrate specificity of MRP1, we generated a series of eight mutant proteins in which Ser1233 , Ser1235 , Ser1237 , Gln1239 , Thr1241 , and Asn1245 were replaced with Ala, and Tyr1236 and Tyr1243 were substituted with Phe (Fig. 1). Login to comment
113 Mutation of one polar-aromatic residue, Y1243F, caused an approximately 2-3-fold reduction of resistance to all four drugs, whereas three mutations, Y1236F, T1241A, and N1245A, resulted in a 2-3-fold loss of resistance to only certain drugs. Login to comment
115 In contrast, conversion of Asn1245 to Ala resulted in a mutant protein with enhanced resistance to vincristine (1.6-fold) but a 2-3-fold partial decrease in the ability to confer resistance to VP-16, doxorubicin, and epirubicin. Login to comment
117 Subcellular Localization of Mutant and Wild Type MRP1 in Transfected HEK293 Cells-To determine whether effects of mutations Y1236F, T1241A, Y1243F, and N1245A on the drug FIG. 1. Login to comment
142 However, mutations Y1243F and N1245A both decreased the levels of E217betaG transport ϳ5-6-fold (Fig. 5). Login to comment
144 Kinetic Parameters of [3 H]LTC4 and [3 H]E217betaG Transport-We have shown that mutation Y1243F affected the ability of the protein to transport both LTC4 and E217betaG and that mutation N1245A decreased the transport of only E217betaG. Login to comment
158 For wild type MRP1 and mutant MRP1N1245A, the Km values for LTC4 uptake were identical (90 nM), and the normalized Vmax value for N1245A was also very similar to that of wild type MRP1 (Vmax ϭ 100 pmol/mg/ min for mutation N1245A; 117 pmol/mg/min for wild type MRP1) (Table II). Login to comment
162 For E217betaG transport, a nonlinear regression analysis of the data generated a Km value of 1.4 ␮M for wild type MRP1, consistent with previous estimates (10), compared with 5.4 and 10.9 ␮M for mutations Y1243F and N1245A, respectively (Fig. 6 and Table II). Login to comment
163 The normalized Vmax values for mutations Y1243F and N1245A were lower than that for wild type MRP1 (Vmax ϭ 403 pmol/mg/min for wild type MRP1 versus 316 pmol/ mg/min for mutation Y1243F and 288 pmol/mg/min for mutation N1245A) (Fig. 6 and Table II). Login to comment
164 Thus mutations Y1243F and N1245A decreased the Vmax/Km ratio for E217betaG ϳ5-and 11-fold, respectively. Login to comment
165 Effect of Mutations Y1243F and N1245A on the Inhibition of MRP1-mediated E217betaG/LTC4 Transport by LTC4/ E217betaG-As an alternative means of assessing the effects of the TM17 mutations on the interaction between LTC4 and the human protein, we examined the ability of LTC4 to inhibit transport of E217betaG. Login to comment
168 Converting Asn1245 to Ala reproducibly decreased the IC50 value (207 nM), whereas mutation of Tyr1243 to Phe resulted in a slight, reproducible increase (407 nM). Login to comment
170 For the wild type protein, the IC50 value for E217betaG was 3.6 ␮M compared with 11.8 ␮M for mutation Y1243F and 15.1 ␮M for mutation N1245A. Login to comment
171 Since these results are independent of protein expression levels, they provide additional evidence that the observed decrease in transport of mutations Y1243F and N1245A at nonsaturating concentrations of E217betaG is primarily attributable to changes in the affinity of the proteins for this substrate. Login to comment
218 Substitution of Asn1245 with Ala decreased the resistance to VP-16 and the two anthracyclines tested, consistent with the involvement of hydrogen bonding in the interaction with these drugs. Login to comment
230 By analogy, conversion of Asn1245 to Ala in MRP1 may increase accessibility to a relatively large substrate, such as vincristine, whereas the loss of hydrogen bonding may contribute to the decrease in resistance to other drugs, such as VP-16, doxorubicin, and epirubicin. 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

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