Insights into the structure and substrate interactions of the P-glycoprotein multidrug transporter from spectroscopic studies

Sharom, Frances J.; Liu, Ronghua; Romsicki, Yolanda; Lu, Peihua

doi:10.1016/s0005-2736(99)00166-2

Cited by 100 publications

(87 citation statements)

References 85 publications

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“…An unresolved question concerns the role (if any) of Wzm itself in substrate recognition. Substrate-binding sites are located in the TMD component of many ABC efflux systems, with the eukaryotic multidrug transporter P-glycoprotein serving as a wellstudied example (24,25). The current data suggest that Wzm is not involved in O-PS specificity but does not rule out its possible recognition of features present in both O8 and O9a polymers.…”

Section: Discussionmentioning

confidence: 99%

Substrate binding by a bacterial ABC transporter involved in polysaccharide export

Cuthbertson

Kimber

Whitfield

2007

Proc. Natl. Acad. Sci. U.S.A.

118

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Section: Discussionmentioning

confidence: 99%

Substrate binding by a bacterial ABC transporter involved in polysaccharide export

Cuthbertson

Kimber

Whitfield

2007

Proc. Natl. Acad. Sci. U.S.A.

118

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“…However, several lines of evidence suggest that MRP1 and P-gp confer resistance to these drugs by different mechanisms. In vitro studies using P-gp-enriched membrane vesicles or purified reconstituted protein demonstrate that P-gp directly binds and transports its drug substrates in an ATP-dependent manner (11,12). Under similar conditions, MRP1 will only transport unmodified amphipathic drugs, such as vincristine and daunorubicin, in the presence of GSH in addition to ATP (13-17).…”

mentioning

confidence: 99%

Identification of a Nonconserved Amino Acid Residue in Multidrug Resistance Protein 1 Important for Determining Substrate Specificity

Zhang¹,

Cole²,

Deeley

2001

Journal of Biological Chemistry

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Murine multidrug resistance protein 1 (mrp1), differs from its human ortholog (MRP1) in that it fails to confer anthracycline resistance and transports the MRP1 substrate, 17␤-estradiol 17-(␤-D-glucuronide) (E 2 17␤G), very poorly. By mutating variant residues in mrp1 to those present in MRP1, we identified Glu 1089 of MRP1 as being critical for anthracycline resistance. However, Glu 1089 mutations had no effect on E 2 17␤G transport. We have now identified a nonconserved amino acid within the highly conserved COOH-proximal transmembrane helix of MRP1/mrp1 that is important for transport of the conjugated estrogen. Converting Ala 1239 in mrp1 to Thr, as in the corresponding position (1242) in MRP1, increased E 2 17␤G transport 3-fold. Any mutation of mrp1 Ala 1239 , including substitution with Thr, decreased resistance to vincristine and VP-16 without altering anthracycline resistance. However, introduction of a second murine to human mutation, Q1086E, which alone selectively increases anthracycline resistance, into mrp1A1239T restored resistance to both vincristine and VP-16. To confirm the importance of MRP1 Thr 1242 for E 2 17␤G transport and drug resistance, we mutated this residue to Ala, Cys, Ser, Leu, and Lys. These mutations decreased E 2 17␤G transport 2-fold. Conversion to Asp eliminated transport of the estrogen conjugate and also decreased leukotriene C 4 transport ϳ2-fold. The mutations also reduced the ability of MRP1 to confer resistance to all drugs tested. As with mrp1, introduction of a second mutation based on the murine sequence to create MRP1E1089Q/ T1242A restored resistance to vincristine and VP-16, but not anthracyclines, without affecting transport of leukotriene C 4 and E 2 17␤G. These results demonstrate the important role of Thr 1242 for E 2 17␤G transport. They also reveal a highly specific functional relationship between nonconserved amino acids in TM helices 14 and 17 of both mrp1 and MRP1 that enables both proteins to confer similar levels of resistance to vincristine and VP-16.Human multidrug resistance protein 1 (MRP1), 1 a 190-kDa glycoprotein, is a member of the ATP-binding cassette (ABC) transporter superfamily (1-3). The predicted structure of MRP1 differs from that of a typical eukaryotic ABC transporter such as P-glycoprotein (P-gp). It contains a P-gp-like core region, which consists of two membrane-spanning domains (MSDs), each containing six transmembrane (TM) ␣-helices, and two nucleotide binding domains. However, MRP1 contains a third MSD predicted to consist of five TM ␣-helices with an extracellular NH 2 terminus and a cytoplasmic linker connecting the additional MSD with the core region (3-7). Like P-gp, MRP1 confers resistance to many commonly used, structurally diverse natural product chemotherapeutic agents including anthracyclines, Vinca alkaloids, and epipodophyllotoxins (7-10). However, several lines of evidence suggest that MRP1 and P-gp confer resistance to these drugs by different mechanisms. In vitro studies using P-gp-enriched membrane vesicles or purifi...

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“…5-HT is considered to increase the intracellular cAMP level via 5-HT receptors, but the possibility that chronic 5-HT depletion enhances trafficking cannot be excluded, as is the case for the intracellular Ca 2ϩ level. Moreover, phosphorylation and glycosylation of P-gp and membrane conditions where P-gp is located are suggested to be factors regulating the activity and expression of P-gp (Castro et al, 1999;Sharom et al, 1999;Gribar et al, 2000). Therefore, further investigation is needed to clarify the mechanisms behind the induction of P-gp expression in the brush-border membrane by 5-HT depletion.…”

Section: Discussionmentioning

confidence: 99%

Up-Regulation of P-Glycoprotein Expression in Small Intestine under Chronic Serotonin-Depleted Conditions in Rats

Hiraoka¹,

Kimura²,

Furukawa³

et al. 2004

J Pharmacol Exp Ther

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To investigate the role of serotonin (5-HT), an important neurotransmitter and hormone/paracrine agent in the small intestine, in the transport activity of P-glycoprotein (P-gp), the intestinal transport of quinidine, a P-gp substrate, was examined in 5-HTdepleted rats prepared by intraperitoneal administration of pchlorophenylalanine, a specific inhibitor of tryptophan hydroxylase in 5-HT biosynthesis. In the in vitro transport study, quinidine transport across rat jejunum was significantly enhanced in both the secretory and absorptive directions under 5-HT-depleted conditions, although the secretory transport was still predominant. The electrophysiological study suggested that the quinidine transport via passive diffusion was enhanced presumably through a paracellular route. This might be due to looser tight junctions under 5-HT-depleted conditions. The voltage-clamp technique clearly indicated that the secretory transport of quinidine through the transcellular pathway was also enhanced by the depletion of 5-HT. Furthermore, 5-HT depletion increased verapamil-sensitive secretory transport of quinidine in rat jejunum. These results indicate that the secretory transport of quinidine via P-gp was significantly enhanced under 5-HT-depleted conditions. The level of ATP, an energy source for functioning P-gp, wet weight of jejunum, and total protein level in rat jejunal mucosa were not changed by 5-HT depletion, but the expression of P-gp in the brush-border membrane of rat jejunum was significantly induced, which is partly responsible for the enhancement of P-gp activity under the 5-HT-depleted condition.

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Insights into the structure and substrate interactions of the P-glycoprotein multidrug transporter from spectroscopic studies

Cited by 100 publications

References 85 publications

Substrate binding by a bacterial ABC transporter involved in polysaccharide export

Substrate binding by a bacterial ABC transporter involved in polysaccharide export

Identification of a Nonconserved Amino Acid Residue in Multidrug Resistance Protein 1 Important for Determining Substrate Specificity

Up-Regulation of P-Glycoprotein Expression in Small Intestine under Chronic Serotonin-Depleted Conditions in Rats

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