ABCMdb

ABCC3 p.Thr1237Ala

None has been submitted yet.

Publications

PMID: 12924948 [PubMed] Zhang DW et al: "Characterization of the role of polar amino acid residues within predicted transmembrane helix 17 in determining the substrate specificity of multidrug resistance protein 3."

No. Sentence Comment

9 In contrast, mutation T1237A markedly increased VP-16 resistance and transport of all substrates. Login to comment
75 They are as follows: S1229A (5'-GGG CTG GTG GGG CTA GCT GTG TCC TAC TCC-3'), S1231A (5'-GC CTT TCT GTG GCC TAC TCC CTG CAG GTG ACA-3'), Y1232F (5'-T TCT GTG TCC TTC TCC TTA CAG GTG ACA TTT G-3'), S1233A (5'-CT GTG TCC TAC GCC CTG CAG GTG ACA TTT G-3'), Q1235A (5'-G TCC TAC TCC TTG GCG GTG ACA TTT GCT C-3'), T1237A (5'-CC TTG CAG GTG GCA TTC GCT CTG AAC TGG-3'), T1237S (5'-CC TTG CAG GTG TCC TTC GCT CTG AAC TGG-3'), T1237G (5'-CC TTG CAG GTG GGA TTC GCT CTG AAC TGG-3'), T1237L (5'-CC TTG CAG GTG CTA TTC GCT CTG AAC TGG-3'), and N1241A (5'-GTG ACA TTT GCG CTA GCC TGG ATG ATA C-3'). Login to comment
139 In contrast, conversion of Thr1237 to Ala resulted in a significant (~2.0-fold) increase in transport activity. Login to comment
147 Similar to the results obtained with E217βG as a substrate, substitution of Thr1237 with Ala resulted in a mutant protein that displayed an enhanced transport activity of the drug. Login to comment
151 In contrast, mutations Q1235A and T1237A increased the ability of MRP3 to transport the bile salt approximately 1.5-and 3-fold, respectively. Login to comment
154 We have shown that mutation T1237A increased the ability of MRP3 to transport both E217βG and taurocholate. Login to comment
155 Like mutation T1237A, replacement of Gln1235 with Ala also increased taurocholate uptake. Login to comment
160 The results suggest that mutations Q1235A and T1237A affect a step in the transport process after initial binding of this substrate. Login to comment
161 The effects of mutations Q1235A and T1237A on kinetic parameters of E217βG transport were also examined (Figure 7B, Table 1). Login to comment
180 Interestingly, converting Thr1237 to Ala decreased Km values for E217βG transport by approximately 5-fold (Km ) 6 µM for MRP1T1237A ). Login to comment
182 Thus, in contrast to the results obtained with taurocholate, these findings demonstrated that the increase in E217βG transport observed with the T1237A mutation at subsaturating concentrations was attributable to increased affinity of the protein for this substrate, which is associated with a decrease in Vmax. Login to comment
187 Interestingly, conversion of Thr1237 to Ala resulted in a mutant protein with enhanced resistance to VP-16 (3-fold). Login to comment
188 Thus, on the basis of the substrates tested in this study, mutations S1229A, S1231A, Q1235A, and N1241A affected substrate specificity of MRP3, whereas mutations Y1232F, S1233A, and T1237A influenced the overall activity of the protein. Login to comment
190 Since replacement of Thr1237 with Ala resulted in a mutant protein with an enhanced capacity to confer VP-16 resistance, we also mutated this residue to Gly, Ser, and Leu. Login to comment
193 As shown in Table 2, mutation T1237G, like T1237A, significantly FIGURE 4: ATP-dependent [3H]E217βG uptake by membrane vesicles prepared from HEK293 cells stably transfected with wild-type or mutant MRP3. Panel A: Relative protein expression levels of wild-type and mutant MRP3 proteins in stably transfected HEK293 cells. Login to comment
211 In addition to the effect on VP-16 resistance, substitution of Thr1237 with Ala increased the capacity of MRP3 to transport methotrexate, E217βG, and taurocholate. Login to comment
213 Replacement of Thr1237 with Gly, like mutation T1237A, dramatically increased the ability of MRP3 to transport methotrexate (Figure 8B), E217βG (Figure 8C), and taurocholate (Figure 8D). Login to comment
248 In MRP3, elimination of the hydrogen-bonding capability of Tyr1232 and Ser1233 negatively affected all functions, while mutation of Thr1237 to Ala had a positive effect. Login to comment
288 In addition, conversion of polar residue Thr1237 to either Ala or Gly markedly increased the ability to confer VP-16 resistance and to transport E217βG, taurocholate, and methotrexate, while mutation to a bulkier and more hydrophobic Leu residue resulted in only a moderate increase in transport of all three substrates. Login to comment
292 Interestingly, although mutation T1237A increased the ability of MRP3 to transport both taurocholate and E217βG, the mutation resulted in a major increase in Vmax for taurocholate uptake, without significantly affecting Km values. Login to comment
295 If so, the fact that the T1237A mutations increase the affinity of the protein for E217βG suggests that a single amino acid may contribute both to the high-affinity binding of one substrate and the low-affinity binding of another. Login to comment