UNIPROT:P33527 - FACTA Search

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Query: UNIPROT:P33527 (ABCC1)
1,164 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The 190 kDa multidrug resistance protein 1 (MRP1/ABCC1) is a founding member of a subfamily of the ATP binding cassette (ABC) superfamily of transport proteins and was originally identified on the basis of its elevated expression in multidrug resistant lung cancer cells. In addition to its ability to confer resistance in tumour cells, MRP1 is ubiquitously expressed in normal tissues and is a primary active transporter of GSH, glucuronate and sulfate conjugated and unconjugated organic anions of toxicological relevance. Substrates include lipid peroxidation products, herbicides, tobacco specific nitrosamines, mycotoxins, heavy metals, and natural product and antifolate anti-cancer agents. MRP1 also transports unmodified xenobiotics but often requires GSH to do so. Active efflux is generally an important aspect of cellular detoxification since it prevents the accumulation of conjugated and unconjugated compounds that have the potential to be directly toxic. The related transporters MRP2 and MRP3 have overlapping substrate specificities with MRP1 but different tissue distributions, and evidence that they also have chemoprotective functions are discussed. Finally, MRP homologues have been described in other species including yeast and nematodes. Those isolated from the vascular plant Arabidopsis thaliana (AtMRPs) decrease the cytoplasmic concentration of conjugated toxins through sequestration in vacuoles and are implicated in providing herbicide resistance to plants.
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PMID:Toxicological relevance of the multidrug resistance protein 1, MRP1 (ABCC1) and related transporters. 1155 26

We established several in vitro drug-resistant cell lines after continuous, long-term exposure of each drug to elucidate mechanisms of drug resistance. Whether drug resistance in these in vitro resistant cell lines reflects clinical drug resistance still remains unanswered. In this study, a pair of lung cancer cell lines was established from one patient with squamous cell carcinoma of the lung, with one line being established before and one line after combination chemotherapy (cisplatin/ifosfamide/vindesine). Combination chemotherapy selected resistant EBC-2/R cells, which showed cross-resistance to 4-hydroxyifosfamide (3.2-fold), cisplatin (2.3-fold), and methotrexate (3.7-fold) and collateral sensitivity to vindesine (0.77-fold) compared with parent EBC-2 cells. EBC-2/R cells showed decrease in intracellular accumulation of cisplatin, increase in intracellular concentration of glutathione (GSH), and overexpression of multidrug resistance-associated protein (MRP) 3 when compared with EBC-2 cells. A single cycle of chemotherapy was not sufficient to select other mechanisms of drug resistance, such as multidrug resistance-1/P-glycoprotein, MRPs 1, 2, 4, and 5, lung resistance-related protein, metallothionein IIa, glutathione S-transferase pi, gamma-glutamylcysteine synthetase (light and heavy chain), and excision repair cross complementing 1. Sequentially we established two cell lines, which cell lines showed the differences of the cisplatin resistance, expression level of MRP3, intracellular GSH level and intracellular accumulation of cisplatin. A pair of cell lines will be useful to elucidate resistant mechanisms of cisplatin in heterogeneous lung cancer cells.
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PMID:Characterization of non-small-cell lung cancer cell lines established before and after chemotherapy. 1184 6

Substrates transported by the 190-kDa multidrug resistance protein 1 (MRP1) (ABCC1) include endogenous organic anions such as the cysteinyl leukotriene C(4). In addition, MRP1 confers resistance against various anticancer drugs by reducing intracellular accumulation by co-export of drug with reduced GSH. We have examined the properties of LY475776, an intrinsically photoactivable MRP1-specific tricyclic isoxazole modulator that inhibits leukotriene C(4) transport by this protein in a GSH-dependent manner. We show that [125I]LY475776 photolabeling of MRP1 requires GSH but is also supported by several non-reducing GSH derivatives and peptide analogs. Limited proteolysis revealed that [(125)I]LY475776 labeling was confined to the 75-kDa COOH-proximal half of MRP1. More extensive proteolysis generated two major 125I-labeled fragments of approximately 56 and approximately 41 kDa, and immunoblotting with regionally directed antibodies showed that these fragments correspond to amino acids approximately 1045-1531 and approximately 1150-1531, respectively. However, an approximately 33-kDa COOH-terminal immunoreactive fragment was not labeled, inferring that the major [125I]LY475776-labeling site resides approximately between amino acids 1150-1250. This region encompasses transmembrane (TM) segments 16 and 17 at the COOH-proximal end of the third membrane spanning domain of the protein. [125I]LY475776 labeling of mutant MRP1 molecules with substitutions of Trp(1246) in TM17 were reduced >80% compared with wild-type MRP1, confirming that TM17 is important for LY475776 binding. Finally, vanadate-induced trapping of ADP inhibited [125I]LY475776 labeling, suggesting that ATP hydrolysis causes a conformational change in MRP1 that reduces the affinity of the protein for this inhibitor.
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PMID:GSH-dependent photolabeling of multidrug resistance protein MRP1 (ABCC1) by [125I]LY475776. Evidence of a major binding site in the COOH-proximal membrane spanning domain. 1203 27

Multidrug resistance protein 1 (MRP1/ABCC1) is an ATP-dependent transporter of structurally diverse organic anion conjugates. The protein also actively transports a number of non-conjugated chemotherapeutic drugs and certain anionic conjugates by a presently poorly understood GSH-dependent mechanism. LY475776is a newly developed (125)I-labeled azido tricyclic isoxazole that binds toMRP1 with high affinity and specificity in a GSH-dependent manner. The compound has also been shown to photolabel a site in the COOH-proximal region of MRP1's third membrane spanning domain (MSD). It is presently not known where GSH interacts with the protein. Here, we demonstrate that the photactivateable GSH derivative azidophenacyl-GSH can substitute functionally for GSH in supporting the photolabeling of MRP1 by LY475776 and the transport of another GSH-dependent substrate, estrone 3-sulfate. In contrast to LY475776, azidophenacyl-[(35)S] photolabels both halves of the protein. Photolabeling of the COOH-proximal site can be markedly stimulated by low concentrations of estrone 3-sulfate, suggestive of cooperativity between the binding of these two compounds. We show that photolabeling of the COOH-proximal site by LY475776 and the labeling of both NH(2)- and COOH- proximal sites by azidophenacyl-GSH requires the cytoplasmic linker (CL3) region connecting the first and second MSDs of the protein, but not the first MSD itself. Although required for binding, CL3 is not photolabeled by azidophenacyl-GSH. Finally, we identify non-conserved amino acids in the third MSD that contribute to the high affinity with which LY475776 binds to MRP1.
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PMID:Photolabeling of human and murine multidrug resistance protein 1 with the high affinity inhibitor [125I]LY475776 and azidophenacyl-[35S]glutathione. 1213 19

The multidrug resistance protein, MRP1 (ABCC1), is an ATP-binding cassette transporter that confers resistance to chemotherapeutic agents. MRP1 also mediates transport of organic anions such as leukotriene C(4) (LTC(4)), 17beta-estradiol 17-(beta-d-glucuronide) (E(2)17betaG), estrone 3-sulfate, methotrexate (MTX), and GSH. We replaced three charged amino acids, Lys(332), His(335), and Asp(336), predicted to be in the sixth transmembrane (TM6) helix of MRP1 with neutral and oppositely charged amino acids and determined the effect on substrate specificity and transport activity. All mutants were expressed in transfected human embryonic kidney cells at levels comparable with wild-type MRP1, and confocal microscopy showed that they were correctly routed to the plasma membrane. Vesicular transport studies revealed that the MRP1-Lys(332) mutants had lost the ability to transport LTC(4), and GSH transport was reduced; whereas E(2)17betaG, estrone 3-sulfate, and MTX transport were unaffected. E(2)17betaG transport was not inhibited by LTC(4) and could not be photolabeled with [(3)H]LTC(4), indicating that the MRP1-Lys(332) mutants no longer bound this substrate. Substitutions of MRP1-His(335) also selectively diminished LTC(4) transport and photolabeling but to a lesser extent. Kinetic analyses showed that V(max) (LTC(4)) of these mutants was decreased but K(m) was unchanged. In contrast to the selective loss of LTC(4) transport in the Lys(332) and His(335) mutants, the MRP1-Asp(336) mutants no longer transported LTC(4), E(2)17betaG, estrone 3-sulfate, or GSH, and transport of MTX was reduced by >50%. Lys(332), His(335), and Asp(336) of TM6 are predicted to be in the outer leaflet of the membrane and are all capable of forming intrahelical and interhelical ion pairs and hydrogen bonds. The importance of Lys(332) and His(335) in determining substrate specificity and of Asp(336) in overall transport activity suggests that such interactions are critical for the binding and transport of LTC(4) and other substrates of MRP1.
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PMID:Charged amino acids in the sixth transmembrane helix of multidrug resistance protein 1 (MRP1/ABCC1) are critical determinants of transport activity. 1218 71

MRP1 (or ABCC1) is an ABC membrane protein that transports a wide range of natural products as well as glutathione (GSH)-, glucuronate-, and sulfate-conjugated metabolites. In addition, free GSH is required for MRP1 to transport several chemotherapeutic drugs. However, the mechanisms regulating the influence of GSH on MRP1 is poorly understood, and the location of GSH binding site(s) within MRP1 have yet to be determined. To address these issues, we have synthesized a [(125)I] labeled azido-derivative of GSH (IAAGSH) to photoaffinity label MRP1. Our results revealed that IAAGSH labeled MRP1 with high specificity, and binding was inhibited by MRP1 substrates leukotriene C(4) and MK571. Interestingly, verapamil and vincristine enhanced IAAGSH photolabeling of MRP1, in agreement with observations that both drugs enhance GSH transport. We observed GSH to be the best inhibitor of photoaffinity labeling, as compared to oxidized glutathione (GSSG) and four different GSH alkyl derivatives. These observations indicate that IAAGSH interacted with MRP1 in a similar manner as unmodified GSH. Moreover, using eight MRP1-HA variants, each containing hemagglutinin A (HA) epitopes inserted at different sites in MRP1, we mapped the GSH binding sites in MRP1. Our GSH analogue photoaffinity labeled four MRP1 polypeptides that were located within two cytoplasmic domains in linker sequences (L0 and L1) as well as transmembrane domains 10-11 and 16-17. The photoaffinity labeling of polypeptides within L0 and L1 domains is further confirmed using two MRP1-specific monoclonal antibodies (MRPr1 and QCRL1) with epitopes within the linker domains. Taken together, this study provides the most precise information to date on the location of GSH binding sites in MRP1.
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PMID:Binding of a photoaffinity analogue of glutathione to MRP1 (ABCC1) within two cytoplasmic regions (L0 and L1) as well as transmembrane domains 10-11 and 16-17. 1264 60

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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PMID:Functional and structural consequences of cysteine substitutions in the NH2 proximal region of the human multidrug resistance protein 1 (MRP1/ABCC1). 1273 62

The active outward translocation of phospholipid analogues from the inner to the outer membrane leaflet of human erythrocytes by the multi-drug resistance protein MRP1 (ABCC1) depends on intracellular reduced glutathione (GSH). Entrapment of ATP and increasing amounts of GSH inside resealed ghosts prepared from erythrocytes resulted in an up to six-fold increase of the translocation rate. Entrapped oxidized glutathione (GSSG) acted inhibitory but produced stimulation after addition of the disulphide-reducing reagent dithioerythritol. Modification of GSH by esterification of the C-terminal carboxylate of Gly, removal of the N-terminal Glu or substitution of the SH group by an anionic S-dicarboxyethyl or sulphonate group abolished stimulation. The effect of S-alkylation of GSH depended on the length of the alkyl group. S-methyl GSH was somewhat more effective than GSH, but maximal stimulation was similar. S-butyl GSH acted poorly stimulatory while S-hexyl GSH was essentially ineffective. Analyses of the kinetic data of translocation revealed K(m) values for GSH and methyl-GSH of respectively 7.4 +/- 2.4 and 4.9 +/- 1.1 mmol l(-1). At high GSH levels and defined constant ATP levels using an ATP-regenerating system, the Km for ATP of the outward translocation was 0.16 +/- 0.02 mmol l(-1). In the same system lacking GSH, the Km for ATP of the inward translocation by the aminophospholipid flippase was 0.53 +/- 0.23 mmol l(-1).
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PMID:ATP and GSH dependence of MRP1-mediated outward translocation of phospholipid analogs in the human erythrocyte membrane. 1457 45

Multidrug resistance proteins (MRPs) are ATP-dependent export pumps that mediate the export of organic anions. ABCC1 (MRP1), ABCC2 (MRP2) and ABCC3 (MRP3) are all able to facilitate the efflux of anionic conjugates including glutathione (GSH), glucuronide and sulfate conjugates of xenobiotics and endogenous molecules. Earlier studies showed that ABCC4 functions as an ATP-driven export pump for cyclic AMP and cyclic GMP, as well as estradiol-17-beta-D-glucuronide. However, it was unclear if other conjugated metabolites can be transported by ABCC4. Hence in this study, a fluorescent substrate, bimane-glutathione (bimane-GS) was used to further examine the transport activity of ABCC4. Using cells stably overexpressing ABCC4, this study shows that ABCC4 can facilitate the efflux of the glutathione conjugate, bimane-glutathione. Bimane-glutathione efflux increased with time and >85% of the conjugate was exported after 15min. This transport was abolished in the presence of 2.5microM carbonylcyanide m-chlorophenylhydrasone (CCCP), an uncoupler of oxidative phosphorylation. Inhibition was also observed with known inhibitors of MRP transporters including benzbromarone, verapamil and indomethacin. In addition, 100microM methotrexate, an ABCC4 substrate or 100microM 6-thioguanine (6-TG), a compound whose monophosphate metabolite is an ABCC4 substrate, reduced efflux by >40%. A concentration-dependent inhibition of bimane-glutathione efflux was observed with 1-chloro-2,4-dinitrobenzene (CDNB) which is metabolized intracellularly to the glutathione conjugate, 2,4-dinitrophenyl-glutathione (DNP-GS). The determination that ABCC4 can mediate the transport of glucuronide and glutathione conjugates indicates that ABCC4 may play a role in the cellular extrusion of Phase II detoxification metabolites.
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PMID:Multidrug resistance protein 4 (MRP4/ABCC4) mediates efflux of bimane-glutathione. 1464 90

Drug resistance is a major impediment in the treatment of cancer patients receiving single or multiple drug treatment. Efforts to reverse drug resistance of tumor cells have not been successful. In recent years, considerable emphasis has been placed on understanding the underlying mechanisms that confer drug resistance. The expression of the multidrug resistance protein 1 (MRP1 or ABCC1) in cancer cells has been shown to confer resistance to diverse classes of anti-cancer drugs. MRP1 is a member of the ATP-binding cassette (ABC) family whose function, in tumor cells, is to reduce drug accumulation through energized drug efflux. To learn more about the functions of MRP1 in tumor drug resistance, knowledge of the protein binding characteristics and the location of its binding sites are essential. Photoaffinity labeling (PAL) has emerged as a leading technique that can rapidly shed light on a protein's drug binding characteristics and ultimately drug binding domains. Several MRP1-specific photoreactive probes have been developed. PAL of MRP1 was first demonstrated with the quinoline-based drug, IAAQ. Other studies showed that the high affinity endogenous substrate of MRP1, LTC(4), has intrinsic photoreactive properties and binds within both N- and C-terminal domains of MRP1. LTC(4) is conjugated to glutathione (GSH), a property common to several MRP1 substrates. In addition, several unconjugated drugs have been identified that interact with MRP1: [(3)H]VF-13,159, IAAQ, IACI and IAARh123. Mapping studies showed that IACI and IAARh123 bind two sites within transmembrane (TM) regions 10-11 and 16-17 of MRP1. Interestingly, the GSH-dependent PAL of [(125)I]azidoAG-A and [(125)I]LY475776 occurs within, or proximal to TM 16-17. The PAL with several analogs of GSH, IAAGSH and azidophenacyl-[(35)S]GSH found to interact specifically with MRP1 within TM 10-11 and TM 16-17 in addition to binding two cytoplasmic regions in MRP1, L0 and L1. This review focuses on the use of PAL for studying MRP1 interactions with various drugs and cell metabolites. Furthermore, knowledge of MRP1 drug binding domains, as identified by PAL with various photoreactive drug analogs, provides an important first step towards more detailed analyses of MRP1 binding domains.
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PMID:Drug binding domains of MRP1 (ABCC1) as revealed by photoaffinity labeling. 1475 9

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