ABCMdb

ABCC1 p.Pro1068Ala

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Publications

PMID: 14722114 [PubMed] Koike K et al: "Identification of proline residues in the core cytoplasmic and transmembrane regions of multidrug resistance protein 1 (MRP1/ABCC1) important for transport function, substrate specificity, and nucleotide interactions."

No. Sentence Comment

139 The locations of the MSD3 Pro residues mutated in this study are highlighted, and the approximate boundaries of the TM helices are indicated by dashed lines. B, shown is a representative immunoblot of membrane vesicles prepared from HEK293T cells transfected with empty vector (pcDNA3.1(-)), wild-type (WT-MRP1), and mutant (P1003A, P1060A, P1068A, P1088A, P1113A, P1120A, P1121A, P1150A, and P1191A) MRP1 cDNAs. MRP1 proteins were detected with mAb QCRL-1, and relative levels of expression estimated by densitometry are indicated; equal protein loading was confirmed by Amido Black staining of the polyvinylidene difluoride membrane and is shown below the blot. Login to comment
147 As shown in Fig. 4A, [3 H]LTC4 uptake levels of the P1003A, P1068A, P1088A, and P1150A mutants were ϳ40-50% less than those of wild-type MRP1, whereas LTC4 uptake by the other five MSD3 Pro mutants was similar to wild-type MRP1. Login to comment
148 Levels of [3 H]E217betaG uptake by six of the nine MSD3 mutants (P1003A, P1060A, P1068A, P1088A, P1120A, and P1121A) were moderately reduced (by 30-55%), whereas uptake of this substrate by the P1113A and P1191A mutants was comparable with wild-type MRP1. Login to comment
150 [3 H]MTX uptake by the P1150A mutant was also dramatically increased (ϳ6-fold) whereas uptake of this antifolate by the remaining eight MSD3 Pro mutants was either moderately reduced (by 50-60% for P1068A, P1088A, and P1120A) or comparable with wild-type MRP1 (P1003A, P1060A, P1113A, P1121A, and P1191A) (Fig. 4C). Login to comment
154 Relative to wild-type MRP1, apigenin-stimulated GSH uptake by the P1068A, P1088A, and P1150A mutants was significantly reduced (by 50-70%), whereas uptake by the other six MSD3 Pro FIG. 4. Login to comment
159 TABLE III Summary of effects of MSD3 Pro substitutions on MRP1 vesicular transport activities Substrate % wild-type MRP1 activitya ECL6 P1003A CL6 TM14 P1088A ECL7 P1113A TM15 CL7 P1060A P1068A P1120A P1121A P1150A P1191A LTC4 60 90 60 50 100 100 110 50 90 E217betaG 65 50 55 45 90 60 70 220 90 MTX 80 80 40 45 100 50 85 620 100 GSH 80 95 50 30 120 140 80 35 100 E13SO4 75 75 90 50 120 90 80 65 60 a The values shown are means of triplicate determinations in a single experiment and are representative of results obtained in 2-3 independent experiments (for details, see legend to Fig. 4 and text). Login to comment
162 GSH-stimulated E13SO4 uptake by the P1003A, P1060A, P1088A, P1150A, and P1191A mutants was moderately reduced (by 25-50%), whereas uptake of this sulfated estrogen by the other four MSD3 Pro mutants (P1068A, P1113A, P1120A, and P1121A) was comparable with wild-type MRP1. Login to comment
273 Ala substitution of Pro1060 (in CL6) caused a moderate and selective loss of E217betaG transport, and Ala substitution of Pro1068 (in CL6) caused a moderate overall loss of organic anion transport except for E13SO4 transport, which remained comparable with wild-type MRP1. Login to comment
276 That structural changes are introduced into CL6 by replacement of Pro1060 or Pro1068 with Ala is evident from the loss of immunoreactivity of the P1060A and P1068A mutants with mAb MRPm5 which maps to amino acids 1063-1072.4 However, the moderate changes in the transport properties of the P1060A and P1068A mutants, and the fact that mAb MRPm5 does not inhibit MRP1 transport activity, suggest that considerable mobility of this loop can be accommodated without loss of MRP1 activity.4 CL7 is also predicted to be extensively ␣-helical and, like CL6, contains two Pro residues. Login to comment

PMID: 14975760 [PubMed] Koike K et al: "Mapping of the MRPm5 epitope to the cytosolic region between transmembrane helices 13 and 14 in the drug and organic anion transporter, MRP1 (ABCC1)."

No. Sentence Comment

99 Lack of reactivity of the P1068A MRP1 mutant with the MAb MRPm5 (Fig. 1B) indicates that Pro1068 is also an important component of the MRPm5 epitope. Login to comment