ABCMdb

ABCC1 p.Cys43Ala

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Publications

PMID: 12731862 [PubMed] Leslie EM et al: "Functional and structural consequences of cysteine substitutions in the NH2 proximal region of the human multidrug resistance protein 1 (MRP1/ABCC1)."

No. Sentence Comment

54 Mutagenesis was performed according to the manufacturer`s instructions with the following sense mutagenic primers (substituted nucleotides are underlined and introduced or lost restriction sites are in italics) as follows: Cys43Ala (5'-G TGG GTG CCT GCT TTT TAC CTC TGG GCC-3'), Cys43Ser (5'-G TGG GTG CCT TCT TTT TAC CTC-3'), Cys49Ala (5'-C CTC TGG GCC GCA TTC CCC TTC TAC-3') (BsmI), Cys49Ser (5'-C CTC TGG GCC TCT TTC CCC TTC-3'), Cys85Ala (5'-G TGG ATC GTC GCG TGG GCA GAC C-3') (BstUI), Cys85Ser (5'-G TGG ATC GTC AGC TGG GCA GAC C-3'), Cys148Ala (5'-GTA GCC CTA GTG GCT GCC CTA GCC-3') (BglI), Cys148Ser (5'-GTA GCC CTA GTG TCT GCC CTA GCC-3'), Cys190Ala (5'-C GTC TTG TCC GCA TTC TCA GAT CGC-3') (BsmI), Cys190Ser (5'-C GTC TTG TCC TCT TTC TCA GAT CG-3'), Cys208Ala (5'-C CCT AAT CCC GCG CCA GAG TCC AG-3') (BstUI), Cys208Ser (5'-C CCT AAT CCC AGC CCA GAG TCC-3'), Cys265Ala (5'-GTA AAG AAC TGG AAG AAG GAA GCC GCG AAG ACT AGG AAG CAG-3') (BpiI), and Cys265Ser (5'- GG AAG AAG GAA TCC GCC AAG ACT AG-3') (BsmI). Login to comment
110 Those exhibiting minor disruption of plasma membrane trafficking included cell lines expressing four CysfAla mutants [Cys43Ala (Figure 3C), Cys85Ala (Figure 3G), Cys190Ala (Figure 3K), and Cys208Ala (Figure 3M)] and four CysfSer mutants [Cys49Ser (Figure 3F), Cys85Ser (Figure 3H), Cys190Ser (Figure 3L), and Cys208Ser (Figure 3N)]. Login to comment
111 Three of the mutant cell lines with impaired plasma membrane trafficking of MRP1 exhibited filament-like staining (Cys43Ala, Cys43Ser, and Cys49Ser) (Figure 3C,D,F) while the cell lines expressing Cys265Ala and Cys265Ser MRP1 showed a stippled-like staining pattern. Login to comment
130 Table 1: Detection of Tryptic Fragments N1 and N2 of MRP1 in Membranes Prepared from HeLa Cells Stably Expressing CysfAla and CysfSer MRP1 Mutantsa trypsin:protein ratio (w:w)transfected HeLa cell line N1 detected N2 detected WT-MRP1 1:10 000 1:1000 C43A-MRP1 1:100 1:100 C43S-MRP1 1:10 000 1:1000 C49A-MRP1 1:250 1:100 C49S-MRP1 1:10 000 1:500 C85A-MRP1 1:10 000 1:1000 C85S-MRP1 1:1000 1:250 C148A-MRP1 1:250 1:250 C148S-MRP1 1:1000 1:500 C190A-MRP1 1:1000 1:1000 C190S-MRP1 1:1000 1:250 C208A-MRP1 1:10 000 1:250 C208S-MRP1 1:10 000 1:500 C265A-MRP1 1:250 1:10 C265S-MRP1 1:1000 1:250 a The data shown represent a summary of the limited trypsin digests shown in Figures 4 and 5. Login to comment
134 Trypsinolysis of the four remaining Ala-substituted Cys mutants (Cys148Ala, Cys49Ala, Cys43Ala, and Cys265Ala) showed that they were also quite resistant to cleavage by this enzyme. Login to comment
135 For example, the N1 and N2 fragments of Cys148Ala-MRP1 did not appear until a trypsin:protein ratio of 1:250 while the N1 and N2 fragments of Cys49Ala-MRP1 appeared at ratios of 1:250 and 1:100, respectively. The Cys43Ala-MRP1 mutant was highly resistant to trypsinolysis with the appearance of the N1 band not occurring until the trypsin:protein ratio was 1:100, the same ratio at which the N2 band appeared. Login to comment
136 The Cys265Ala MRP1 was less resistant than the Cys43Ala mutant with the N1 fragment appearing at a trypsin:protein ratio of 1:250. Login to comment
154 In contrast, E217 G uptake by membrane vesicles prepared from Cys43Ala-MRP1 expressing cells increased 40% relative to uptake by WT-MRP1. Login to comment
173 Consequently, we examined the resistance of cells expressing mutant MRP1 molecules harboring substitutions of Cys residues in MSD1 (Cys43Ala, Cys43Ser, Cys49Ala, Cys49Ser, Cys190Ala, and Cys190Ser) andCL3(Cys208Ala,Cys208Ser,Cys265Ala,andCys265Ser), to sodium arsenite and potassium antimony tartrate. Login to comment
181 The Cys43Ala, Cys43Ser, Cys265Ala, and Cys265Ser MRP1 mutant expressing cell lines were 6.5-, 2.6-, 7.1-, and 5.1-fold resistant to doxorubicin, respectively, levels of resistance that did not differ significantly from the ~5-fold resistance observed with cells expressing WT-MRP1 (Figure 8A). Login to comment
182 In contrast, the cell line expressing Cys43Ser-MRP1 was only 5-fold resistant to vincristine while the cell lines expressing Cys43Ala, Cys265Ala, and Cys265Ser-MRP1 were 21-, 19-, and 13-fold resistant, respectively, levels of resistance comparable to those observed in cells expressing WT-MRP1 (15-fold resistant) (Figure 8B). Login to comment
192 Table 2: Sensitivity of Stably Transfected HeLa Cells Expressing Wild-Type and Cys-Substituted MRP1 to Sodium Arsenite and Potassium Antimony Tartrate relative resistancea transfected HeLa cell line Na+ arsenite K+ antimony tartrate WT-MRP1 3.6 ( 1.3 (1) (n ) 6) 2.0 ( 0.5 (1) (n ) 7) C43A-MRP1 4.3 ( 0.7 (1.2) (n ) 3) 2.0 ( 0.4 (1) (n ) 3) C43S-MRP1 1.4 ( 0.5 (0.4)b (n ) 6) 2.8 ( 1.1 (1.4) (n ) 4) C49A-MRP1 4.0 ( 1.6 (1.1) (n ) 5) 2.6 ( 0.7 (1.3) (n ) 4) C49S-MRP1 3.0 ( 1.5 (0.8) (n ) 4) 3.0 ( 0.6 (1.5) (n ) 4) C190A-MRP1 3.8 ( 0.4 (1) (n ) 4) 4.0 ( 1.2 (2) (n ) 3) C190S-MRP1 2.9 ( 0.4 (0.8) (n ) 4) 2.7 ( 0.4 (1.4) (n ) 3) C208A-MRP1 3.0 ( 0.6 (0.8) (n ) 3) 2.4 ( 0.6 (1.2) (n ) 3) C208S-MRP1 4.2 ( 0.8 (1.2) (n ) 3) 3.8 ( 0.7 (1.9) (n ) 3) C265A-MRP1 2.5 ( 0.2 (0.7) (n ) 4) 2.3 ( 0.6 (0.9) (n ) 3) C265S-MRP1 10.2 ( 0.4 (2.8)b (n ) 5) 4.0 ( 1.7 (2) (n ) 3) a The resistance of stably transfected HeLa cells was determined using a tetrazolium-based cytotoxicity assay. The relative resistance factors were obtained by dividing the IC50 values for wild-type or Cys mutant MRP1 transfected cells by the IC50 values for empty vector control transfected cells and were normalized for differences in MRP1 expression levels. Login to comment
203 The most significant decreases were observed in membranes from cells expressing the Cys43Ala, Cys49Ala, Cys148Ala, and Cys265Ala MRP1 mutants, suggesting that an alteration in the conformation of these proteins has occurred that decreases the accessibility of specific trypsin cleavage sites in CL3 (appearance of N2 fragment) and, in some cases, in the linker region of the protein between NBD1 and MSD3 (appearance of N1 fragment). Login to comment