Structural Determinants of Substrate Specificity Differences between Human Multidrug Resistance Protein (MRP) 1 (ABCC1) and MRP3 (ABCC3)

2008 ◽  
Vol 36 (12) ◽  
pp. 2571-2581 ◽  
Author(s):  
Caroline E. Grant ◽  
Mian Gao ◽  
Marianne K. DeGorter ◽  
Susan P. C. Cole ◽  
Roger G. Deeley
Keyword(s):  
Multidrug Resistance ◽  
Substrate Specificity ◽  
Multidrug Resistance Protein ◽  
Structural Determinants ◽  
Resistance Protein

Substitution of Trp1242 of TM17 alters substrate specificity of human multidrug resistance protein 3

2003 ◽  
Vol 284 (2) ◽  
pp. G280-G289 ◽  
Author(s):  
Curtis J. Oleschuk ◽  
Roger G. Deeley ◽  
Susan P. C. Cole
Keyword(s):  
Multidrug Resistance ◽  
Substrate Specificity ◽  
Multidrug Resistance Protein ◽  
Wild Type ◽  
Multidrug Resistance Protein 3 ◽  
17Β Estradiol ◽  
Resistance Protein ◽  
Estradiol 17Β ◽  
Taurocholate Transport

Multidrug resistance protein 3 (MRP3) is an ATP-dependent transporter of 17β-estradiol 17β(d-glucuronide) (E217βG), leukotriene C4 (LTC4), methotrexate, and the bile salts taurocholate and glycocholate. In the present study, the role of a highly conserved Trp residue at position 1242 on MRP3 transport function was examined by expressing wild-type MRP3 and Ala-, Cys-, Phe-, Tyr-, and Pro-substituted mutants in human embryonic kidney 293T cells. Four MRP3-Trp1242 mutants showed significantly increased E217βG uptake, whereas transport by the Pro mutant was undetectable. Similarly, the Pro mutant did not transport LTC4. By comparison, LTC4transport by the Ala, Cys, Phe, and Tyr mutants was reduced by ∼35%. The Ala, Cys, Phe, and Tyr mutants all showed greatly reduced methotrexate and leucovorin transport, except the Tyr mutant, which transported leucovorin at levels comparable with wild-type MRP3. In contrast, the MRP3-Trp1242 substitutions did not significantly affect taurocholate transport or taurocholate and glycocholate inhibition of E217βG uptake. Thus Trp1242 substitutions markedly alter the substrate specificity of MRP3 but leave bile salt binding and transport intact.

scholarly journals Multiple Membrane-associated Tryptophan Residues Contribute to the Transport Activity and Substrate Specificity of the Human Multidrug Resistance Protein, MRP1

2002 ◽  
Vol 277 (51) ◽  
pp. 49495-49503 ◽  
Author(s):  
Koji Koike ◽  
Curtis J. Oleschuk ◽  
Anass Haimeur ◽  
Sharon L. Olsen ◽  
Roger G. Deeley ◽  
...  
Keyword(s):  
Multidrug Resistance ◽  
Substrate Specificity ◽  
Organic Anion ◽  
Selective Reduction ◽  
Multidrug Resistance Protein ◽  
Transport Activity ◽  
Binding Domains ◽  
17Β Estradiol ◽  
Resistance Protein ◽  
Estradiol 17Β

The multidrug resistance protein, MRP1, is a clinically important ATP-binding cassette transporter in which the three membrane-spanning domains (MSDs), which contain up to 17 transmembrane (TM) helices, and two nucleotide binding domains (NBDs) are configured MSD1-MSD2-NBD1-MSD3-NBD2. In tumor cells, MRP1 confers resistance to a broad spectrum of drugs, but in normal cells, it functions as a primary active transporter of organic anions such as leukotriene C4and 17β-estradiol 17β-(d-glucuronide). We have previously shown that mutation of TM17-Trp1246eliminates 17β-estradiol 17β-(d-glucuronide) transport and drug resistance conferred by MRP1 while leaving leukotriene C4transport intact. By mutating the 11 remaining Trp residues that are in predicted TM segments of MRP1, we have now determined that five of them are also major determinants of MRP1 function. Ala substitution of three of these residues, Trp445(TM8), Trp553(TM10), and Trp1198(TM16), eliminated or substantially reduced transport levels of five organic anion substrates of MRP1. In contrast, Ala substitutions of Trp361(TM7) and Trp459(TM9) caused a more moderate and substrate-selective reduction in MRP1 function. More conservative substitutions (Tyr and Phe) of the Trp445, Trp553, and Trp1198mutants resulted in substrate selective retention of transport in some cases (Trp445and Trp1198) but not others (Trp553). Our findings suggest that the bulky polar aromatic indole side chain of each of these five Trp residues contributes significantly to the transport activity and substrate specificity of MRP1.

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