ABCMdb

ABCC1 p.Ala481Gly

Predicted by SNAP2:	C: D (59%), D: D (80%), E: D (80%), F: D (63%), G: N (93%), H: D (80%), I: D (63%), K: D (75%), L: D (71%), M: D (53%), N: D (66%), P: D (85%), Q: D (75%), R: D (80%), S: N (57%), T: N (72%), V: N (57%), W: D (66%), Y: D (75%),
Predicted by PROVEAN:	C: D, D: D, E: D, F: D, G: N, H: D, I: D, K: D, L: D, M: D, N: D, P: D, Q: D, R: D, S: N, T: N, V: D, W: D, Y: D,

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Publications
[hide] Structural determinants of substrate specificity d... Drug Metab Dispos. 2008 Dec;36(12):2571-81. Epub 2008 Sep 5. Grant CE, Gao M, DeGorter MK, Cole SP, Deeley RG
Structural determinants of substrate specificity differences between human multidrug resistance protein (MRP) 1 (ABCC1) and MRP3 (ABCC3).
Drug Metab Dispos. 2008 Dec;36(12):2571-81. Epub 2008 Sep 5., [PMID:18775981]

Abstract [show]
Multidrug resistance proteins (MRPs) are members of the "C" branch of the ATP-binding cassette transporter superfamily. Human MRP1 transports a wide range of natural product drugs and structurally diverse conjugated and unconjugated organic anions. Its closest relative is MRP3. Despite their structural similarity, the homologs differ substantially in their substrate specificity. It is noteworthy that MRP1 transports glutathione (GSH) and GSH conjugates and displays GSH-stimulated transport of a number of unconjugated and conjugated compounds. In contrast, MRP3 does not transport GSH and is a poor transporter of GSH conjugates. However, both proteins transport glucuronide conjugates, such as 17beta-estradiol 17-(beta-D-glucuronide). We have constructed a series of MRP1/MRP3 hybrids and used them to identify a region of MRP1 that is critical for binding and transport of GSH conjugates such as leukotriene C(4) (LTC(4)). Substitution of this region encompassing transmembrane helices 8 and 9 and portions of cytoplasmic loops 4 and 5 of MRP1 with the equivalent region of MRP3 eliminated LTC(4) transport. Transport of other substrates was either unaffected or enhanced. We identified three residues in this region: Tyr(440), Ile(441), and Met(443), mutation of which differentially affected transport. It is noteworthy that substitution of Tyr(440) with Phe, as found in MRP3, reduced LTC(4) and GSH-stimulated estrone-3-sulfate transport without affecting transport of other substrates tested. The mutation increased the K(m) for LTC(4) 5-fold and substantially reduced photolabeling of MRP1 by both [3H]LTC(4) and the GSH derivative, azidophenacyl-[35S]GSH. These results suggest that Tyr(440) makes a major contribution to recognition of GSH and the GSH moiety of conjugates such as LTC(4).

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No. Sentence Comment
140 A second double mutation, A481G/V482A, located in the G2 region also reduced LTC4 transport by 6-fold, and in this case, E217betaG transport was reduced to approximately one third of wild-type MRP1 levels (data not shown). Login to comment
193 Mutations Included 23 M443L/Y440F/1441L 24 A481G/V482A/M483V/M485V 25 V479L/A481G/V482A/M483V/M485V 26 A493K/H494Q/S497L/N500S 27 V479L/A481G/V482A/M483V/M485V 28 V479L/A481G/V482A/M483V/N500S 29 A493K/H494Q/S497L/N500S/N506S 30 A493K/H494Q/S497L/N506S/T487M/K488R/T489A/Y490F consequence, it was technically impossible to determine an accurate Km for LTC4. Login to comment