ABCMdb

ABCC1 p.Cys85Ala

Predicted by SNAP2:	A: N (82%), D: D (59%), E: D (59%), F: D (75%), G: N (57%), H: D (63%), I: D (53%), K: D (63%), L: D (53%), M: D (59%), N: N (61%), P: D (63%), Q: D (53%), R: D (53%), S: N (87%), T: N (78%), V: N (57%), W: D (91%), Y: D (80%),
Predicted by PROVEAN:	A: D, D: D, E: D, F: D, G: D, H: D, I: D, K: D, L: D, M: D, N: D, P: D, Q: D, R: D, S: D, T: D, V: D, W: D, Y: D,

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[hide] Functional and structural consequences of cysteine... Biochemistry. 2003 May 13;42(18):5214-24. Leslie EM, Letourneau IJ, Deeley RG, Cole SP
Functional and structural consequences of cysteine substitutions in the NH2 proximal region of the human multidrug resistance protein 1 (MRP1/ABCC1).
Biochemistry. 2003 May 13;42(18):5214-24., 2003-05-13 [PMID:12731862]

Abstract [show]
The 190 kDa multidrug resistance protein 1 (MRP1; ABCC1) is comprised of three membrane spanning domains (MSDs) and two nucleotide binding domains (NBDs) configured MSD1-MSD2-NBD1-MSD3-NBD2. MRP1 overexpression in tumor cells results in an ATP-dependent efflux of many oncolytic agents and arsenic and antimony oxyanions. MRP1 also transports GSSG and GSH as well as conjugated organic anions, including leukotriene C(4) and 17beta-estradiol 17-(beta-D-glucuronide) and certain xenobiotics in association with GSH. Previous studies have shown that portions of MSD1 and the cytoplasmic loop (CL3) connecting it to MSD2 are important for MRP1 transport function. In the present study, Cys residues at positions 43, 49, 85, 148, and 190 in MSD1 and positions 208 and 265 in CL3 were mutated to Ala and Ser, and the effects on protein expression, plasma membrane localization, trypsin sensitivity, organic anion transport, and drug resistance properties were investigated. Confocal microscopy showed that 11 of 14 mutants displayed significant levels of nonplasma membrane-associated MRP1. Most mutant proteins were also more resistant to trypsin proteolysis than wild-type MRP1. All Cys mutants transported organic anions (0.5-1.5-fold wild-type MRP1 activity), and cells expressing Ser-substituted but not Ala-substituted Cys43 and Cys265 MRP1 mutants exhibited a 2.5-fold decrease and a 3-fold increase in arsenite resistance, respectively; Cys43Ser MRP1 also conferred lower levels of vincristine resistance. These results indicate that certain Cys residues in the NH(2) proximal region of MRP1 can be important for its structure and selected transport activities.

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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
124 The tryptic digest patterns of Cys43Ser and Cys85Ala-MRP1 were almost indistinguishable from that of WT-MRP1, with the appearance of the N1 fragment and faint N2 bands at trypsin:protein ratios of 1:10 000 and 1:1000, respectively. The tryptic digest patterns for vesicles prepared from mutants FIGURE 2: Expression levels of wild-type and Cys-substituted MRP1 in stably transfected HeLa cells. 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
149 However, in contrast to Cys85Ala-MRP1, which transported LTC4 at levels similar to WT-MRP1, Cys85Ser-MRP1 showed a 38% reduction in LTC4 uptake. Login to comment
153 Thus, a moderate (32-42%) decrease in E217 G uptake activity was observed for four of the five mutants (Cys49Ala-MRP1, Cys85Ala-MRP1, Cys148Ala-MRP1, and Cys265Ala-MRP1). Login to comment
157 In contrast to the Cys85Ala mutant, E217 G uptake by Cys85Ser-MRP1 was similar to WT-MRP1. Login to comment