ABCMdb

ABCB1 p.Gly1179Asp

Predicted by SNAP2:	A: D (85%), C: D (85%), D: D (95%), E: D (95%), F: D (91%), H: D (91%), I: D (91%), K: D (95%), L: D (91%), M: D (91%), N: D (91%), P: D (95%), Q: D (91%), R: D (95%), S: D (91%), T: D (91%), V: D (91%), W: D (95%), Y: D (95%),
Predicted by PROVEAN:	A: D, C: D, D: D, E: D, F: 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, W: D, Y: D,

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Publications
[hide] Role of glycine-534 and glycine-1179 of human mult... Biochem J. 2001 May 15;356(Pt 1):71-5. Szakacs G, Ozvegy C, Bakos E, Sarkadi B, Varadi A
Role of glycine-534 and glycine-1179 of human multidrug resistance protein (MDR1) in drug-mediated control of ATP hydrolysis.
Biochem J. 2001 May 15;356(Pt 1):71-5., 2001-05-15 [PMID:11336637]

Abstract [show]
The human multidrug resistance protein (MDR1) (P-glycoprotein), a member of the ATP-binding cassette (ABC) family, causes multidrug resistance by an active transport mechanism, which keeps the intracellular level of hydrophobic compounds below a cell-killing threshold. Human MDR1 variants with mutations affecting a conserved glycine residue within the ABC signature of either or both ABC units (G534D, G534V, G1179D and G534D/G1179D) were expressed and characterized in Spodoptera frugiperda (Sf9) cell membranes. These mutations caused a loss of measurable ATPase activity but still allowed ATP binding and the formation of a transition-state intermediate (nucleotide trapping). In contrast with the wild-type protein, in which substrate drugs accelerate nucleotide trapping, in the ABC signature mutants nucleotide trapping was inhibited by MDR1-substrate drugs, suggesting a miscommunication between the drug-binding site(s) and the catalytic domains. Equivalent mutations of the two catalytic sites resulted in a similar effect, indicating the functional equivalence of the two sites. On the basis of these results and recent structural information on an ABC-ABC dimer [Hopfner, Karcher, Shin, Craig, Arthur, Carney and Tainer (2000) Cell 101, 789-800], we propose a key role of these glycine residues in the interdomain communication regulating drug-induced ATP hydrolysis.

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No. Sentence Comment
6 Human MDR1 variants with mutations affecting a conserved glycine residue within the ABC signature of either or both ABC units (G534D, G534V, G1179D and G534D\G1179D) were expressed and characterized in Spodoptera frugiperda (Sf9) cell membranes. Login to comment
48 Two internal complementary primers were used, each containing the specific mutation (G1179D, 5h-TCTGGTGATCAGAAACAACGCAT-3h). Login to comment
57 The product and the pAcUW21-LMDR1 vector were digested with NotI and PstI, and the product was ligated into the vector, resulting in pAcUW21-L-G1179D. Login to comment
59 The pAcUW21-G534D\G1179D construct was engineered by replacing the 1177-3372 EcoRI-PstI fragment of pAcUW21-G534D with that of pAcUW21-L- G1179D. Login to comment
81 Figure 1 also shows that both the G1179D mutant (affecting the equipositional glycine in the C-terminal ABC unit) and the variant containing aspartic residues at both sides (G534D\ Figure 1 Expression of the MDR1 signature mutants Isolated Sf9 cell membranes (10 µg) expressing G534D-MDR1 (lane 1), G1179D-MDR1 (lane 2), G534D/G1179D-MDR1 (lane 3), G534V-MDR1 (lane 4) or wild-type MDR1 (lane 5) were run on SDS/7.5% (w/v) PAGE gels. Login to comment
85 G1179D) could be expressed efficiently in Sf9 cells. Login to comment
96 We observed nucleotide trapping in mutants G534D, Figure 2 Binding of [α-32 P]8-azido-ATP by the MDR1 signature mutants ATP-binding was performed with isolated Sf9 cell membranes (100 µg) expressing G534V-MDR1 (lane 1), wild-type MDR1 (lanes 2 and 8), G534D-MDR1 (lanes 3 and 4), β- galactosidase (lane 5), G534D/G1179D-MDR1 (lane 6) or G1179D-MDR1 (lane 7). Login to comment
100 Membranes expressing G534D/G1179D-MDR1 (lanes 1 and 2), G534V-MDR1 (lanes 3-5), G534D-MDR1 (lanes 6-8) or G1179D-MDR1 (lanes 9-11) were incubated at 37 mC for 10 min in the presence of 20 µM [α-32 P]8-azido-Mg-ATP as described in the Materials and methods section. Login to comment
104 G534V and G1179D in the presence of AlF % - (see Figure 3) or BeFx (results not shown). Login to comment
107 Interestingly, neither G534D-MDR1 nor G1179D-MDR1 was labelled in the presence of vanadate, not even at higher azido-ATP concentrations and longer incubation times (up to 100 µM and 10 min respectively), whereas G534V showed vanadate-induced nucleotide trapping activity (results not shown). Login to comment
114 Conversely, the same reaction with the ABC signature mutants G534D (ratio 0.32), G534V (ratio 0.41) and G1179D (ratio 0.48) was inhibited by verapamil (36 µM). Login to comment
116 Inhibition persisted over a wide range of azido-ATP concentration (5-50 µM) and was observed in the presence of other drugs (calcein-AM, vincristine, cyclosporin A; results not Figure 4 Effect of verapamil on transition-state formation (nucleotide trapping) in the presence of AlF4 - Labelling was performed with isolated Sf9 cell membranes (100 µg) expressing wild-type MDR1 (lanes 1 and 2), G534V-MDR1 (lanes 3 and 4), G534D-MDR1 (lanes 5 and 6) or G1179D-MDR1 (lanes 7 and 8) as described in the Materials and methods section. Login to comment
119 The positions of molecular-mass markers are indicated (in kDa) at the right. Figure 5 Limited proteolysis of the ABC signature mutants after nucleotide trapping in the presence of AlF4 - Labelling was performed with isolated Sf9 cell membranes (200 µg) expressing wild-type MDR1 (lane 1), G534D-MDR1 (lane 2), G534V-MDR1 (lane 3), G1179D-MDR1 (lane 4) or β- galactosidase (lane 5). Login to comment
130 Nevertheless, as shown in Figure 5, catalytic intermediates stabilized by AlF % - were formed in both ABC domains of the G534D, G534V and the G1179D mutants (BeFx gave similar results; results not shown). Login to comment