ABCC1 p.Trp261Ala
| Predicted by SNAP2: | A: D (75%), C: D (63%), D: D (85%), E: D (80%), F: D (66%), G: D (80%), H: D (75%), I: D (71%), K: D (85%), L: D (71%), M: N (61%), N: D (85%), P: D (85%), Q: D (80%), R: D (80%), S: D (80%), T: D (80%), V: D (66%), Y: D (66%), |
| Predicted by PROVEAN: | A: D, C: 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, Y: D, |
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[hide] Glutathione-dependent binding of a photoaffinity a... J Biol Chem. 2001 Jun 22;276(25):23197-206. Epub 2001 Apr 11. Ren XQ, Furukawa T, Aoki S, Nakajima T, Sumizawa T, Haraguchi M, Chen ZS, Kobayashi M, Akiyama S
Glutathione-dependent binding of a photoaffinity analog of agosterol A to the C-terminal half of human multidrug resistance protein.
J Biol Chem. 2001 Jun 22;276(25):23197-206. Epub 2001 Apr 11., 2001-06-22 [PMID:11301332]
Abstract [show]
MRP1 is a 190-kDa membrane glycoprotein that confers multidrug resistance (MDR) to tumor cells. MRP1 is characterized by an N-terminal transmembrane domain (TMD(0)), which is connected to a P-glycoprotein-like core region (DeltaMRP) by a cytoplasmic linker domain zero (L(0)). It has been demonstrated that GSH plays an important role in MRP1-mediated MDR. However, the mechanism by which GSH mediates MDR and the precise roles of TMD(0) and L(0) are not known. We synthesized [(125)I]11-azidophenyl agosterol A ([(125)I]azidoAG-A), a photoaffinity analog of the MDR-reversing agent, agosterol A (AG-A), to photolabel MRP1, and found that the analog photolabeled the C-proximal molecule of MRP1 (C(932-1531)) in a manner that was GSH-dependent. The photolabeling was inhibited by anticancer agents, reversing agents and leukotriene C(4). Based on photolabeling studies in the presence and absence of GSH using membrane vesicles expressing various truncated, co-expressed, and mutated MRP1s, we found that L(0) is the site on MRP1 that interacts with GSH. This study demonstrated that GSH is required for the binding of an unconjugated agent to MRP1 and suggested that GSH interacts with L(0) of MRP1. The photoanalog of AG-A will be useful for identifying the drug binding site within MRP1, and the role of GSH in transporting substrates by MRP1.
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No. Sentence Comment
91 The primers used to introduce two mutations, K267M and W261A, into MRP1 were 5Ј-GAGTGCGCCAT- GACTAGGAAG-3Ј (forward) and 5Ј-CTTCTTCGCGTTCTTTACCA- AAAC-3Ј (reverse) encoding mismatched bases (bold).
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ABCC1 p.Trp261Ala 11301332:91:55
status: NEW255 This was tested by substituting Trp261 and Lys267 with Ala and Met, respectively, and the subsequent mutated L0 region tested in binding studies.
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ABCC1 p.Trp261Ala 11301332:255:32
status: NEW[hide] MRP1 mutated in the L0 region transports SN-38 but... Biochem Pharmacol. 2005 Oct 1;70(7):1056-65. Noguchi T, Ren XQ, Aoki S, Igarashi Y, Che XF, Nakajima Y, Takahashi H, Mitsuo R, Tsujikawa K, Sumizawa T, Haraguchi M, Kobayashi M, Goto S, Kanehisa M, Aikou T, Akiyama S, Furukawa T
MRP1 mutated in the L0 region transports SN-38 but not leukotriene C4 or estradiol-17 (beta-D-glucuronate).
Biochem Pharmacol. 2005 Oct 1;70(7):1056-65., 2005-10-01 [PMID:16098482]
Abstract [show]
Multidrug resistance protein 1 (MRP1) is an ATP-binding cassette transporter that confers multidrug resistance on tumor cells. Much convincing evidence has accumulated that MRP1 transports most substances in a GSH-dependent manner. On the other hand, several reports have revealed that MRP1 can transport some substrates independently of GSH; however, the importance of GSH-independent transport activity is not well established and the mechanistic differences between GSH-dependent and -independent transport by MRP1 are unclear. We previously demonstrated that the amino acids W261 and K267 in the L0 region of MRP1 were important for leukotriene C4 (LTC4) transport activity of MRP1 and for GSH-dependent photolabeling of MRP1 with azidophenyl agosterol-A (azidoAG-A). In this paper, we further tested the effect of W222L, W223L and R230A mutations in MRP1, designated dmL0MRP1, on MRP1 transport activity. SN-38 is an active metabolic form of CPT-11 that is one of the most promising anti-cancer drugs. Membrane vesicles prepared from cells expressing dmL0MRP1 could transport SN-38, but not LTC4 or estradiol-17 (beta-D-glucuronate), and could not be photolabeled with azidoAG-A. These data suggested that SN-38 was transported by a different mechanism than that of GSH-dependent transport. Understanding the GSH-independent transport mechanism of MRP1, and identification of drugs that are transported by this mechanism, will be critical for combating MRP1-mediated drug resistance. We performed a pairwise comparison of compounds that are transported by MRP1 in a GSH-dependent or -independent manner. These data indicated that it may be possible to predict compounds that are transported by MRP1 in a GSH-independent manner.
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No. Sentence Comment
60 In order to completely disrupt LTC4 transport activity, we created additional mutations in the L0 region of MRP1 that already expressed the W261A and K267M mutations.
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ABCC1 p.Trp261Ala 16098482:60:140
status: NEW63 Practically, the W261A and K267M mutations were first introduced into wt MRP1 by PCR using primers described in a previous paper [15].
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ABCC1 p.Trp261Ala 16098482:63:17
status: NEW136 As described in Section 2, the new mutant MRP1, named dmL0MRP1, was designed to carry the extra mutations, W222L, W223L and R230A, in addition to the previous mutants, W261A and K267M, in L0 region, and the original TMD0 region, in order to avoid the influence of deletion of the TMD0 region (Fig. 1).
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ABCC1 p.Trp261Ala 16098482:136:168
status: NEW[hide] Portrait of multifaceted transporter, the multidru... Pflugers Arch. 2007 Feb;453(5):621-41. Epub 2006 Dec 23. Bakos E, Homolya L
Portrait of multifaceted transporter, the multidrug resistance-associated protein 1 (MRP1/ABCC1).
Pflugers Arch. 2007 Feb;453(5):621-41. Epub 2006 Dec 23., [PMID:17187268]
Abstract [show]
MRP1 (ABCC1) is a peculiar member of the ABC transporter superfamily for several aspects. This protein has an unusually broad substrate specificity and is capable of transporting not only a wide variety of neutral hydrophobic compounds, like the MDR1/P-glycoprotein, but also facilitating the extrusion of numerous glutathione, glucuronate, and sulfate conjugates. The transport mechanism of MRP1 is also complex; a composite substrate-binding site permits both cooperativity and competition between various substrates. This versatility and the ubiquitous tissue distribution make this transporter suitable for contributing to various physiological functions, including defense against xenobiotics and endogenous toxic metabolites, leukotriene-mediated inflammatory responses, as well as protection from the toxic effect of oxidative stress. In this paper, we give an overview of the considerable amount of knowledge which has accumulated since the discovery of MRP1 in 1992. We place special emphasis on the structural features essential for function, our recent understanding of the transport mechanism, and the numerous assignments of this transporter.
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No. Sentence Comment
97 Typical substrates, which are transported as glutathione or glucuronide conjugates, e.g., LTC4 or E217βG, are not transported by an MRP1 variant mutated in the L0 region (W222L, W223L, R231A, W261A, K267M).
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ABCC1 p.Trp261Ala 17187268:97:198
status: NEW[hide] Defining a binding pocket for sulfonylureas in ATP... FASEB J. 2007 Jan;21(1):18-25. Epub 2006 Nov 16. Vila-Carriles WH, Zhao G, Bryan J
Defining a binding pocket for sulfonylureas in ATP-sensitive potassium channels.
FASEB J. 2007 Jan;21(1):18-25. Epub 2006 Nov 16., [PMID:17110465]
Abstract [show]
Sulfonylurea receptors SUR1 and SUR2 are the regulatory subunits of K(ATP) channels. Their differential affinity for hypoglycemic sulfonylureas provides a basis for the selectivity of these compounds for different K(ATP) channel isoforms. Sulfonylureas have a 100- to 1000-fold greater affinity for SUR1 vs. SUR2. Structure-activity studies suggested a bipartite binding pocket. Chimeric SUR1 approximately SUR2 receptors have shown TMD2, the third bundle of transmembrane helices, to be part of an "A" site that confers SUR1 selectivity for sulfonylureas. The purpose of this study is to determine the position of the "B" site. Previous photoaffinity labeling studies have placed the B site on the amino-terminal third of SUR and colabeled the associated K(IR). In our study, deletion of TMD0, the first bundle of transmembrane helices, did not compromise labeling. Further deletions into the cytoplasmic linker, L0, eliminated binding and labeling. Alanine substitutions in L0 identified a limited number of conserved residues, Y230 and W232, important for affinity labeling. A fragment of K(IR)6.2, missing M2 and the entire carboxyl terminal, assembles with SUR1 and is affinity labeled, while deletion of 10 or more amino-terminal residues compromises labeling. These studies indicate that the B site involves L0 and the K(IR) amino terminus, elements that are critical for control of channel gating.
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No. Sentence Comment
100 Additionally, it was observed that GSH-dependent photoaffinity labeling of MRP1 requires the L0 linker and a double mutation, W261A and K267M, in L0 decreased labeling three-fold (35).
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ABCC1 p.Trp261Ala 17110465:100:126
status: NEW99 Additionally, it was observed that GSH-dependent photoaffinity labeling of MRP1 requires the L0 linker and a double mutation, W261A and K267M, in L0 decreased labeling three-fold (35).
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ABCC1 p.Trp261Ala 17110465:99:126
status: NEW