XB-ART-52262
PLoS Pathog
2016 Jul 21;127:e1005725. doi: 10.1371/journal.ppat.1005725.
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Molecular Mechanisms for Drug Hypersensitivity Induced by the Malaria Parasite's Chloroquine Resistance Transporter.
Richards SN
,
Nash MN
,
Baker ES
,
Webster MW
,
Lehane AM
,
Shafik SH
,
Martin RE
.
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Mutations in the Plasmodium falciparum 'chloroquine resistance transporter' (PfCRT) confer resistance to chloroquine (CQ) and related antimalarials by enabling the protein to transport these drugs away from their targets within the parasite's digestive vacuole (DV). However, CQ resistance-conferring isoforms of PfCRT (PfCRTCQR) also render the parasite hypersensitive to a subset of structurally-diverse pharmacons. Moreover, mutations in PfCRTCQR that suppress the parasite's hypersensitivity to these molecules simultaneously reinstate its sensitivity to CQ and related drugs. We sought to understand these phenomena by characterizing the functions of PfCRTCQR isoforms that cause the parasite to become hypersensitive to the antimalarial quinine or the antiviral amantadine. We achieved this by measuring the abilities of these proteins to transport CQ, quinine, and amantadine when expressed in Xenopus oocytes and complemented this work with assays that detect the drug transport activity of PfCRT in its native environment within the parasite. Here we describe two mechanistic explanations for PfCRT-induced drug hypersensitivity. First, we show that quinine, which normally accumulates inside the DV and therewithin exerts its antimalarial effect, binds extremely tightly to the substrate-binding site of certain isoforms of PfCRTCQR. By doing so it likely blocks the normal physiological function of the protein, which is essential for the parasite's survival, and the drug thereby gains an additional killing effect. In the second scenario, we show that although amantadine also sequesters within the DV, the parasite's hypersensitivity to this drug arises from the PfCRTCQR-mediated transport of amantadine from the DV into the cytosol, where it can better access its antimalarial target. In both cases, the mutations that suppress hypersensitivity also abrogate the ability of PfCRTCQR to transport CQ, thus explaining why rescue from hypersensitivity restores the parasite's sensitivity to this antimalarial. These insights provide a foundation for understanding clinically-relevant observations of inverse drug susceptibilities in the malaria parasite.
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Species referenced: Xenopus laevis
Genes referenced: app
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Fig 1. Isoforms of PfCRTK1 localize to the surface of Xenopus oocytes.(A) Immunofluorescence microscopy was used to localize PfCRT in the oocyte. In each case, the expression of the PfCRT variant resulted in a fluorescent band external to the pigment layer, indicating that the protein was expressed in the oocyte plasma membrane. The band was not present in noninjected oocytes. The images are representative of at least two independent experiments (performed using oocytes from different frogs), within which images were obtained from a minimum of three oocytes per oocyte type. (B) The level of PfCRT protein in the oocyte membrane was semiquantified using a western blot method [42]. The analysis included PfCRTK1 as a positive control, to which the other band intensity values were normalized. The data are the mean + SEM of at least five independent experiments (performed using oocytes from different frogs), within which measurements were averaged from two independent replicates. There were no significant differences in expression levels between constructs (P > 0.05; one-way ANOVA); hence, all of the PfCRT variants were present at similar levels in the oocyte membrane. |
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Fig 2. CQ, quinine, and quinidine transport activities differ significantly between isoforms of PfCRTK1.Noninjected oocytes accumulate low levels of CQ, quinine, and quinidine via simple diffusion of the neutral species of the drug [29, 30]. This represents the background level of drug accumulation. In all cases, the concentration of the [3H]drug under study was 0.25 μM. (A) The uptake of [3H]CQ was measured at pH 6.0 and in the presence of 15 μM unlabeled CQ. The rates of CQ uptake (pmol per oocyte/h) in noninjected oocytes and oocytes expressing PfCRTK1 were 0.98 ± 0.13 and 6.75 ± 0.94, respectively. (B, C) The uptake of [3H]quinine or [3H]quinidine was measured at pH 5.0 and in the presence of 1 μM of the respective unlabeled drug. The rates of uptake (pmol per oocyte/h) in noninjected oocytes and oocytes expressing PfCRTK1 were 0.10 ± 0.01 and 0.55 ± 0.03, respectively, for quinine and 0.063 ± 0.010 and 0.38 ± 0.08, respectively, for quinidine. Note that the relatively low total concentration of quinine and quinidine (1.25 μM) used in these assays enabled the detection of [3H]quinine transport via the 76I-PfCRTK1 isoform. However, this low drug concentration also resulted in rates of quinine and quinidine transport that were 10–15 times lower than those measured for CQ (a difference which corresponds well with the ~12-fold reduction in the total concentration of quinine or quinidine relative to the total concentration of CQ). In all panels, drug uptake is expressed relative to that measured in oocytes expressing PfCRTK1 and the data are the mean + SEM of at least five independent experiments (performed using oocytes from different frogs), within which measurements were made from 10 oocytes per treatment. The asterisks denote a significant difference in drug uptake between the noninjected treatment and that measured in oocytes expressing a variant of PfCRT: *P < 0.05; **P < 0.01; ***P < 0.001 (one-way ANOVA). |
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Fig 3. Isoforms of PfCRTK1 from amantadine-hypersensitive parasites transport amantadine.(A) Amantadine inhibits the transport of [3H]CQ via 76I-PfCRTK1 and 76I,369F-PfCRTK1 in a concentration-dependent manner (IC50s of 186 ± 16 and 174 ± 26 μM, respectively). (B) The uptake of [3H]amantadine (0.146 μM) in the absence and presence of verapamil or saquinavir. The measurements were undertaken at pH 5.0 and in the presence of 50 μM unlabeled amantadine. (C) The PfCRT-mediated transport of [3H]amantadine. Using the data shown for the solvent control in panel B, the component of [3H]amantadine transport attributable to PfCRT was calculated by subtracting the background level of accumulation (i.e., the average of the uptake measured in noninjected oocytes and oocytes expressing 76K-PfCRTK1) from that measured for each of the oocyte types. The rates of amantadine uptake (nmol per oocyte/h) in noninjected oocytes and PfCRTK1-expressing oocytes were 5.4 ± 0.9 and 12 ± 2.8, respectively. The asterisks denote a significant difference from the noninjected control: *P < 0.05; **P < 0.01; ***P < 0.001 (one-way ANOVA). (D) Trans-stimulation of PfCRT-mediated [3H]CQ transport by unlabeled amantadine. The oocytes were microinjected with a buffer control or with buffer containing amantadine, spermine, or histidine. The estimated intracellular concentrations ([compound]i) are indicated. The asterisks denote a significant difference from the relevant buffer-injected control. (E) Concentration-dependence of the trans-stimulation of [3H]CQ uptake by amantadine. The oocytes were microinjected with buffer containing amantadine to achieve an estimated [amantadine]i of 1 to 20 mM. The app Km and app Vmax values are the apparent kinetic parameters for the trans-stimulatory effect of amantadine. The data show CQ uptake above that measured in the relevant buffer-injected control; the total rates of CQ uptake are presented in S6 Fig. The noninjected data overlays the data obtained with oocytes expressing PfNT1, PfCRT3D7, or 76K-PfCRTK1. (F) A magnified plot of the 76I-PfCRTK1 and 76I,369F-PfCRTK1 data from panel E. In all panels, the data are the mean ± SEM of five independent experiments (performed using oocytes from different frogs), within which measurements were made from 10 oocytes per treatment. Where not shown, error bars fall within the symbols. |
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Fig 4. Amantadine is a substrate of PfCRTDd2 and PfCRT7G8, and not of wild-type PfCRT, in situ.The rate of concanamycin A-induced DV alkalinization (expressed as the inverse of the half-time for DV alkalinization) in the C2GC03 (CQ-sensitive, expressing PfCRT3D7), C4Dd2 (CQ-resistant, expressing PfCRTDd2), and C67G8 (CQ-resistant, expressing PfCRT7G8) transfectant lines was measured in the absence and presence of amantadine (AMT), CQ, or verapamil (VP). The effect of amantadine on the DV alkalinization rate was also measured in the presence of verapamil (final concentration of 50 μM). The drugs were added to suspensions of saponin-isolated trophozoite-stage parasites containing fluorescein-dextran in their DVs 4 min before the addition of concanamycin A (100 nM). CQ was added at a concentration of 2.5 μM and the concentration of amantadine was 10 μM. Consistent with previous studies, the addition of CQ elevated the rate of alkalinization in both of the CQ-resistant lines and had a small buffering effect in the C2GC03 parasites [34–36, 46]. The biological basis for the difference in the rate of CQ-dependent alkalinization between the two CQ-resistant lines is currently unclear, but could be due to differences in (1) the expression of PfCRT, (2) the transport properties of the two PfCRT isoforms, (3) the volume of the DV, and/or (4) the concentration of PfCRT’s natural substrates within the DV. The data are the mean + SEM of five independent experiments (performed on different days). The asterisks denote a significant difference from the relevant solvent control: ***P < 0.001 (one-way ANOVA). |
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Fig 5. Molecular mechanisms for the drug hypersensitivities induced by PfCRT isoforms in the malaria parasite.(A) The variants of PfCRTK1 that contain 72R, 76K, 163R, 352K, or 352R (R/K) do not possess significant quinine (QN) transport activity. The drug would therefore remain in the parasite’s DV where it exerts an anti-hemozoin effect that kills the parasite, which is consistent with the QN-sensitive (S) status of the respective lines. PfCRTK1 (76T) is able to transport QN out of the DV and thereby imparts low-level resistance (low-R) to QN. By contrast, 76I-PfCRTK1 has an extremely high affinity for QN coupled with an extremely low maximum rate of transport. This causes QN to clog the binding site of 76I-PfCRTK1, thereby blocking the transport of the natural substrate. Hence, the QN-hypersensitivity (hyper-S) observed in 106/176I parasites results from QN exerting two killing effects—anti-hemozoin and anti-PfCRTCQR. The gain of a positively-charged residue at position 72 or 352 (76I R/K) prevents the interaction of the transporter with QN and returns the parasites to QN-sensitive status. (B) Amantadine (AMT) is a relatively poor inhibitor of both 76I-PfCRTK1 and 76I,369F-PfCRTK1, making it unlikely that the AMT-hypersensitivity of CQ-resistant parasites is due to an anti-PfCRTCQR effect. The isoforms of PfCRT from AMT-hypersensitive parasites (PfCRTK1 and 76I-PfCRTK1) have the ability to transport this weak-base drug out of the DV (where it accumulates) whereas those from AMT-sensitive parasites either do not possess significant AMT transport activity (e.g., 76K-PfCRTK1 and 163R,356V-PfCRTK1; R/K) or transport AMT with low affinity and low capacity (76I,369F-PfCRTK1). The data therefore converge on a scenario in which AMT exerts its main antimalarial activity in the cytosol and AMT-hypersensitivity arises from the redistribution of the drug from the DV into the cytosol via a PfCRTCQR variant (e.g., PfCRTK1 or 76I-PfCRTK1). |
References [+] :
Adjalley,
Genome-wide transcriptome profiling reveals functional networks involving the Plasmodium falciparum drug resistance transporters PfCRT and PfMDR1.
2015, Pubmed
Adjalley, Genome-wide transcriptome profiling reveals functional networks involving the Plasmodium falciparum drug resistance transporters PfCRT and PfMDR1. 2015, Pubmed
Allen, Plasmodium falciparum culture: the benefits of shaking. 2010, Pubmed
Barnes, Selection for high-level chloroquine resistance results in deamplification of the pfmdr1 gene and increased sensitivity to mefloquine in Plasmodium falciparum. 1992, Pubmed
Baro, Function of resistance conferring Plasmodium falciparum chloroquine resistance transporter isoforms. 2013, Pubmed
Bellanca, Multiple drugs compete for transport via the Plasmodium falciparum chloroquine resistance transporter at distinct but interdependent sites. 2014, Pubmed , Xenbase
Bray, PfCRT and the trans-vacuolar proton electrochemical gradient: regulating the access of chloroquine to ferriprotoporphyrin IX. 2006, Pubmed
Bröer, Comparison of lactate transport in astroglial cells and monocarboxylate transporter 1 (MCT 1) expressing Xenopus laevis oocytes. Expression of two different monocarboxylate transporters in astroglial cells and neurons. 1997, Pubmed , Xenbase
Callaghan, Functional Comparison of 45 Naturally Occurring Isoforms of the Plasmodium falciparum Chloroquine Resistance Transporter (PfCRT). 2015, Pubmed
Carter, Isolation and functional characterization of the PfNT1 nucleoside transporter gene from Plasmodium falciparum. 2000, Pubmed , Xenbase
Chugh, Identification and deconvolution of cross-resistance signals from antimalarial compounds using multidrug-resistant Plasmodium falciparum strains. 2015, Pubmed
Combrinck, Insights into the role of heme in the mechanism of action of antimalarials. 2013, Pubmed
Conrad, Comparative impacts over 5 years of artemisinin-based combination therapies on Plasmodium falciparum polymorphisms that modulate drug sensitivity in Ugandan children. 2014, Pubmed
Cooper, Mutations in transmembrane domains 1, 4 and 9 of the Plasmodium falciparum chloroquine resistance transporter alter susceptibility to chloroquine, quinine and quinidine. 2007, Pubmed
Cooper, Alternative mutations at position 76 of the vacuolar transmembrane protein PfCRT are associated with chloroquine resistance and unique stereospecific quinine and quinidine responses in Plasmodium falciparum. 2002, Pubmed
Dahl, Multiple antibiotics exert delayed effects against the Plasmodium falciparum apicoplast. 2007, Pubmed
Deane, Chlorpheniramine Analogues Reverse Chloroquine Resistance in Plasmodium falciparum by Inhibiting PfCRT. 2014, Pubmed , Xenbase
Delves, The activities of current antimalarial drugs on the life cycle stages of Plasmodium: a comparative study with human and rodent parasites. 2012, Pubmed
Eastman, PfCRT and PfMDR1 modulate interactions of artemisinin derivatives and ion channel blockers. 2016, Pubmed
Ecker, PfCRT and its role in antimalarial drug resistance. 2012, Pubmed
Ecker, Tricks in Plasmodium's molecular repertoire--escaping 3'UTR excision-based conditional silencing of the chloroquine resistance transporter gene. 2012, Pubmed
Evans, Plasmodium falciparum: effects of amantadine, an antiviral, on chloroquine-resistant and -sensitive parasites in vitro and its influence on chloroquine activity. 1993, Pubmed
Famin, Kinetics of inhibition of glutathione-mediated degradation of ferriprotoporphyrin IX by antimalarial drugs. 1999, Pubmed
Fidock, Mutations in the P. falciparum digestive vacuole transmembrane protein PfCRT and evidence for their role in chloroquine resistance. 2000, Pubmed
Fitch, Ferriprotoporphyrin IX, phospholipids, and the antimalarial actions of quinoline drugs. 2004, Pubmed
Griffin, Mutation in the Plasmodium falciparum CRT protein determines the stereospecific activity of antimalarial cinchona alkaloids. 2012, Pubmed
Hawley, Relationship between antimalarial drug activity, accumulation, and inhibition of heme polymerization in Plasmodium falciparum in vitro. 1998, Pubmed
Hayward, The pH of the digestive vacuole of Plasmodium falciparum is not associated with chloroquine resistance. 2006, Pubmed
Held, In vitro activity of tigecycline in Plasmodium falciparum culture-adapted strains and clinical isolates from Gabon. 2010, Pubmed
Hrycyna, Quinine dimers are potent inhibitors of the Plasmodium falciparum chloroquine resistance transporter and are active against quinoline-resistant P. falciparum. 2014, Pubmed , Xenbase
Imamovic, Use of collateral sensitivity networks to design drug cycling protocols that avoid resistance development. 2013, Pubmed
Jiang, Genome-wide compensatory changes accompany drug- selected mutations in the Plasmodium falciparum crt gene. 2008, Pubmed
Jing, Functional studies indicate amantadine binds to the pore of the influenza A virus M2 proton-selective ion channel. 2008, Pubmed , Xenbase
Johnson, Evidence for a central role for PfCRT in conferring Plasmodium falciparum resistance to diverse antimalarial agents. 2004, Pubmed
Klonis, Evaluation of pH during cytostomal endocytosis and vacuolar catabolism of haemoglobin in Plasmodium falciparum. 2007, Pubmed
Kornhuber, Lipophilic cationic drugs increase the permeability of lysosomal membranes in a cell culture system. 2010, Pubmed
Kublin, Reemergence of chloroquine-sensitive Plasmodium falciparum malaria after cessation of chloroquine use in Malawi. 2003, Pubmed
Lambros, Synchronization of Plasmodium falciparum erythrocytic stages in culture. 1979, Pubmed
Lehane, A verapamil-sensitive chloroquine-associated H+ leak from the digestive vacuole in chloroquine-resistant malaria parasites. 2008, Pubmed
Lehane, Efflux of a range of antimalarial drugs and 'chloroquine resistance reversers' from the digestive vacuole in malaria parasites with mutant PfCRT. 2010, Pubmed
Lehane, Chloroquine resistance-conferring mutations in pfcrt give rise to a chloroquine-associated H+ leak from the malaria parasite's digestive vacuole. 2008, Pubmed
Lewis, Metabolic QTL analysis links chloroquine resistance in Plasmodium falciparum to impaired hemoglobin catabolism. 2014, Pubmed
Lukens, Harnessing evolutionary fitness in Plasmodium falciparum for drug discovery and suppressing resistance. 2014, Pubmed
Martin, Chloroquine transport via the malaria parasite's chloroquine resistance transporter. 2009, Pubmed , Xenbase
Martin, Saquinavir inhibits the malaria parasite's chloroquine resistance transporter. 2012, Pubmed , Xenbase
Martin, The malaria parasite's chloroquine resistance transporter is a member of the drug/metabolite transporter superfamily. 2004, Pubmed
Miotto, Genetic architecture of artemisinin-resistant Plasmodium falciparum. 2015, Pubmed
Mu, Plasmodium falciparum genome-wide scans for positive selection, recombination hot spots and resistance to antimalarial drugs. 2010, Pubmed
Mu, Recombination hotspots and population structure in Plasmodium falciparum. 2005, Pubmed
Mungthin, Central role of hemoglobin degradation in mechanisms of action of 4-aminoquinolines, quinoline methanols, and phenanthrene methanols. 1998, Pubmed
Mwai, In vitro activities of piperaquine, lumefantrine, and dihydroartemisinin in Kenyan Plasmodium falciparum isolates and polymorphisms in pfcrt and pfmdr1. 2009, Pubmed
Naudé, Dictyostelium discoideum expresses a malaria chloroquine resistance mechanism upon transfection with mutant, but not wild-type, Plasmodium falciparum transporter PfCRT. 2005, Pubmed
Ord, Seasonal carriage of pfcrt and pfmdr1 alleles in Gambian Plasmodium falciparum imply reduced fitness of chloroquine-resistant parasites. 2007, Pubmed
Papakrivos, Functional characterization of the Plasmodium falciparum chloroquine-resistance transporter (PfCRT) in transformed Dictyostelium discoideum vesicles. 2012, Pubmed
Peel, A strong association between mefloquine and halofantrine resistance and amplification, overexpression, and mutation in the P-glycoprotein gene homolog (pfmdr) of Plasmodium falciparum in vitro. 1994, Pubmed
Pelleau, Adaptive evolution of malaria parasites in French Guiana: Reversal of chloroquine resistance by acquisition of a mutation in pfcrt. 2015, Pubmed
Petersen, Balancing drug resistance and growth rates via compensatory mutations in the Plasmodium falciparum chloroquine resistance transporter. 2015, Pubmed
Pluchino, Collateral sensitivity as a strategy against cancer multidrug resistance. 2012, Pubmed
Pradines, In vitro activities of antibiotics against Plasmodium falciparum are inhibited by iron. 2001, Pubmed
Pulcini, Mutations in the Plasmodium falciparum chloroquine resistance transporter, PfCRT, enlarge the parasite's food vacuole and alter drug sensitivities. 2015, Pubmed , Xenbase
Pál, Collateral sensitivity of antibiotic-resistant microbes. 2015, Pubmed
Ramya, Inhibitors of nonhousekeeping functions of the apicoplast defy delayed death in Plasmodium falciparum. 2007, Pubmed
Reed, Pgh1 modulates sensitivity and resistance to multiple antimalarials in Plasmodium falciparum. 2000, Pubmed
SZYBALSKI, Genetic studies on microbial cross resistance to toxic agents. I. Cross resistance of Escherichia coli to fifteen antibiotics. 1952, Pubmed
Sahu, In vitro and in vivo anti-malarial activity of tigecycline, a glycylcycline antibiotic, in combination with chloroquine. 2014, Pubmed
Saliba, Role for the plasmodium falciparum digestive vacuole in chloroquine resistance. 1998, Pubmed
Saliba, pH regulation in the intracellular malaria parasite, Plasmodium falciparum. H(+) extrusion via a V-type H(+)-ATPase. 1999, Pubmed
Sanchez, Evidence for a pfcrt-associated chloroquine efflux system in the human malarial parasite Plasmodium falciparum. 2005, Pubmed
Sanchez, Genetic linkage analyses redefine the roles of PfCRT and PfMDR1 in drug accumulation and susceptibility in Plasmodium falciparum. 2011, Pubmed
Sanchez, Evidence for a substrate specific and inhibitable drug efflux system in chloroquine resistant Plasmodium falciparum strains. 2004, Pubmed
Schneider, NIH Image to ImageJ: 25 years of image analysis. 2012, Pubmed
Sidhu, In vitro efficacy, resistance selection, and structural modeling studies implicate the malarial parasite apicoplast as the target of azithromycin. 2007, Pubmed
Sidhu, Chloroquine resistance in Plasmodium falciparum malaria parasites conferred by pfcrt mutations. 2002, Pubmed
Sidhu, pfmdr1 mutations contribute to quinine resistance and enhance mefloquine and artemisinin sensitivity in Plasmodium falciparum. 2005, Pubmed
Sisowath, In vivo selection of Plasmodium falciparum parasites carrying the chloroquine-susceptible pfcrt K76 allele after treatment with artemether-lumefantrine in Africa. 2009, Pubmed
Siwo, Predicting functional and regulatory divergence of a drug resistance transporter gene in the human malaria parasite. 2015, Pubmed
Smilkstein, Simple and inexpensive fluorescence-based technique for high-throughput antimalarial drug screening. 2004, Pubmed
Somé, Selection of known Plasmodium falciparum resistance-mediating polymorphisms by artemether-lumefantrine and amodiaquine-sulfadoxine-pyrimethamine but not dihydroartemisinin-piperaquine in Burkina Faso. 2010, Pubmed
Spry, Pantothenamides are potent, on-target inhibitors of Plasmodium falciparum growth when serum pantetheinase is inactivated. 2013, Pubmed
Summers, Diverse mutational pathways converge on saturable chloroquine transport via the malaria parasite's chloroquine resistance transporter. 2014, Pubmed , Xenbase
Summers, Functional characteristics of the malaria parasite's "chloroquine resistance transporter": implications for chemotherapy. 2010, Pubmed , Xenbase
Summers, Know your enemy: understanding the role of PfCRT in drug resistance could lead to new antimalarial tactics. 2012, Pubmed
Sá, Geographic patterns of Plasmodium falciparum drug resistance distinguished by differential responses to amodiaquine and chloroquine. 2009, Pubmed
Taylor, Accumulation of free amino acids in growing Xenopus laevis oocytes. 1987, Pubmed , Xenbase
Valderramos, Identification of a mutant PfCRT-mediated chloroquine tolerance phenotype in Plasmodium falciparum. 2010, Pubmed
Van Tyne, Identification and functional validation of the novel antimalarial resistance locus PF10_0355 in Plasmodium falciparum. 2011, Pubmed
Venkatesan, Polymorphisms in Plasmodium falciparum chloroquine resistance transporter and multidrug resistance 1 genes: parasite risk factors that affect treatment outcomes for P. falciparum malaria after artemether-lumefantrine and artesunate-amodiaquine. 2014, Pubmed
Waller, Chloroquine resistance modulated in vitro by expression levels of the Plasmodium falciparum chloroquine resistance transporter. 2003, Pubmed
Wang, Decreased prevalence of the Plasmodium falciparum chloroquine resistance transporter 76T marker associated with cessation of chloroquine use against P. falciparum malaria in Hainan, People's Republic of China. 2005, Pubmed
Weise, Enzymatic suppression of the membrane conductance associated with the glutamine transporter SNAT3 expressed in Xenopus oocytes by carbonic anhydrase II. 2007, Pubmed , Xenbase
Yuan, Chemical genomic profiling for antimalarial therapies, response signatures, and molecular targets. 2011, Pubmed
van Schalkwyk, Verapamil-Sensitive Transport of Quinacrine and Methylene Blue via the Plasmodium falciparum Chloroquine Resistance Transporter Reduces the Parasite's Susceptibility to these Tricyclic Drugs. 2016, Pubmed , Xenbase