ABCMdb

ABCC1 p.Gln1375Leu

None has been submitted yet.

Publications

PMID: 21315686 [PubMed] Yang R et al: "Glutamine residues in Q-loops of multidrug resistance protein MRP1 contribute to ATP binding via interaction with metal cofactor."

No. Sentence Comment

3 However, the Vmax values of the double mutants Q713N/Q1375N, Q713M/Q1375M and Q713L/ Q1375L were lower than that of wtMRP1, implying that the double mutants cannot efficiently bind Mg·ATP. Login to comment
27 In order to determine the functional roles of the glutamine residue in the Q-loop of human MRP1, we have substituted the glutamine residue in Q-loop of MRP1 with: 1) an asparagine (Q713N and Q1375N) that remains the amide group but with one methylene shorter in asparagine than in glutamine; 2) a methionine (Q713M and Q1375M) that eliminates the amide group but contains paired electrons in the sulfur atom of the methionine residue that might potentially interact with the Mg++ cofactor; 3) a leucine (Q713L and Q1375L) that eliminates the amide group and abolishes the interactions with Mg++ cofactor and the putative hydrolytic water molecule, and used them to determine the consequence of these mutations in ATP-dependent leukotriene C4 (LTC4) transport. Login to comment
91 and Q1375L, did not have a significant effect on the ATP-dependent LTC4 transport (Fig. 1C). Login to comment
92 In contrast, the double mutants, including Q713M/Q1375M and Q713L/Q1375L, significantly decreased the ATP-dependent LTC4 transport (Fig. 1C). Login to comment
93 3.2. Substitution of the Q713 in NBD1 or Q1375 in NBD2 with an amino acid that eliminates the interaction between this residue and Mg++ cofactor significantly increased the Km value in ATP-dependent LTC4 transport The results in Fig. 1C imply that the double mutants might significantly affect the binding of Mg·ATP. If this would be the case, it meant that individual mutants, including Q713N, Q1375N, Q713M, Q1375M, Q713L and Q1375L, should also decrease the binding of Mg·ATP. Login to comment
96 The results shown in Fig. S2 clearly indicate that the Vmax and Km (Mg·ATP) values for Q1375L are significantly higher than that for wt MRP1. Login to comment
98 The results in Table 1 indicate that the Vmax values derived from Q713N, Q1375N, Q713 M, Q1375M and Q1375L are significantly higher than that of wt MRP1, whereas the Vmax values of Q713L and the double mutants, including Q713N/ Q1375N, Q713M/Q1375M and Q713L/Q1375L, are not significantly different from that of wt MRP1. Login to comment
100 In addition, the Km (Mg·ATP) values derived from the double mutants are significantly higher than, except Q1375L, their corresponding single mutants. Login to comment
106 As shown in Fig. 2, the mutations at NBD2, including Q1375N, Q1375M and Q1375L, did not have a significant effect on Mg·ATP binding at NBD1, whereas the mutations at NBD1, including Q713N, Q713N/Q1375N, Q713M, Q713M/Q1375M, Q713L and Q713L/ Q1375L, significantly reduced the Mg·ATP binding at NBD1. Login to comment
114 However, the labeling at the mutated NBD2, including Q1375N, Q713N/Q1375N, Q1375M, Q713M/Q1375M, Q1375L and Q713L/Q1375L, with [α-32 P]-8-N3ATP was significantly lower than the corresponding labeling at wt MRP1, implying that much less [α-32 P]-8-N3ATP bound to the mutated NBD2 than to wt MRP1 or the ATP-hydrolysis-product ADP had not been firmly trapped there by vanadate. Login to comment
116 Construct Vmax (pmol/mg/min)a P value Km (μM Mg·ATP)* P value Wt MRP1 104.3±20.5 65.7±4.2 Q713N 191.7±20.9 0.0135 318.3±2.4 0.0001 Q1375N 280.0±32.7 0.0030 370.0±8.2 0.0001 Q713N/Q1375N 63.7±6.9 0.0566 916.7±20.5 0.0001 Q713M 213.3±29.5 0.0128 278.3±19.3 0.0001 Q1375M 203.3±24.9 0.0123 295.0±7.1 0.0001 Q713M/Q1375M 77.0±12.5 0.1249 1006.3±12.7 0.0001 Q713L 120.0±4.1 0.3489 293.3±30.9 0.0005 Q1375L 390.0±24.8 0.0002 900.0±21.6 0.0001 Q713L/Q1375L 88.3±6.2 0.3505 970.0±80.0 0.0006 a Km (Mg·ATP) and Vmax (LTC4) values (n=3) for wild-type and Q713- or Q1375- mutated MRP1 were derived from the corresponding Michaelis-Menten curves (with variant concentration of ATP at 37 °C for 1 min). Login to comment
123 If that would be the case, the double mutant Q713L/Q1375L might require higher concentration of Mg++ to perform the ATP-dependent LTC4 transport. Login to comment
125 As shown in Fig. S3, wt MRP1 transported detectable amount of LTC4 into the membrane vesicles at 0.5-mM MgCl2, whereas Q713L/Q1375L required 5-mM MgCl2 to transport detectable amount of LTC4 into the membrane vesicles. Login to comment
134 Similarly, the percentages (comparing to wt MRP1 as shown in Fig. 4) of the Mn·ATP-dependent LTC4 transport activities of other mutants, including Q713M, Q1375M, Q713M/ Q1375M, Q713L and Q1375L, are also significantly higher than their corresponding percentages (comparing to wt MRP1 as shown in Fig. 1C) of the Mg·ATP-dependent LTC4 transport activities, suggesting that these mutants might have higher affinity for Mn·ATP than for Mg·ATP. If that would be the case, at lower concentration of divalent cation, wt MRP1 should have higher Mn·ATP-dependent LTC4 transport activity than that of Mg·ATP. Login to comment
157 The results presented in this manuscript do not support the above conclusion because the Mn·ATP-dependent LTC4 transport activities of all Q-mutants, except Q713L/Q1375L, are significantly higher than that of wt MRP1 (Fig. 4). Login to comment