ABCMdb

ABCG2 p.Pro623Ala

Predicted by SNAP2:	A: N (82%), C: N (61%), D: N (82%), E: N (57%), F: D (59%), G: N (66%), H: N (53%), I: N (66%), K: N (61%), L: N (61%), M: N (53%), N: N (82%), Q: N (72%), R: N (61%), S: N (93%), T: N (97%), V: N (78%), W: D (59%), Y: D (59%),
Predicted by PROVEAN:	A: N, C: D, D: N, E: N, F: D, G: D, H: D, I: D, K: N, L: D, M: D, N: N, Q: N, R: D, S: N, T: N, V: D, W: D, Y: D,

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Publications
[hide] Identification of proline residues in or near the ... Biochemistry. 2011 Sep 20;50(37):8057-66. Epub 2011 Aug 26. Ni Z, Bikadi Z, Shuster DL, Zhao C, Rosenberg MF, Mao Q
Identification of proline residues in or near the transmembrane helices of the human breast cancer resistance protein (BCRP/ABCG2) that are important for transport activity and substrate specificity.
Biochemistry. 2011 Sep 20;50(37):8057-66. Epub 2011 Aug 26., [PMID:21854076]

Abstract [show]
The human breast cancer resistance protein (BCRP/ABCG2) confers multidrug resistance and mediates the active efflux of drugs and xenobiotics. BCRP contains one nucleotide-binding domain (NBD) followed by one membrane-spanning domain (MSD). We investigated whether prolines in or near the transmembrane helices are essential for BCRP function. Six proline residues were substituted with alanine individually, and the mutants were stably expressed in Flp-In(TM)-293 cells at levels comparable to that of wild-type BCRP and predominantly localized on the plasma membrane of the cells. While P392A showed a significant reduction (35-50%) in the efflux activity of mitoxantrone, BODIPY-prazosin, and Hoechst 33342, P485A exhibited a significant decrease of approximately 70% in the efflux activity of only BODIPY-prazosin. Other mutants had no significant changes in the efflux activities of these substrates. Drug resistance profiles of the cells expressing the mutants correlated well with the efflux data. ATPase activity was not substantially affected for P392A or P485A compared to that of wild-type BCRP. These results strongly suggest Pro(392) and Pro(485) are important in determining the overall transport activity and substrate selectivity of BCRP, respectively. Prazosin differentially affected the binding of 5D3, a conformation-sensitive antibody, to wild-type BCRP, P392A, or P485A in a concentration-dependent manner. In contrast, mitoxantrone had no significant effect on 5D3 binding. Homology modeling indicates that Pro(392) may play an important role in the communication between the MSD and NBD as it is predicted to be located at the interface between the two functional domains, and Pro(485) induces flexible hinges that may be essential for the broad substrate specificity of BCRP.

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No. Sentence Comment
46 Full-length wild-type human BCRP cDNA in pcDNA3.1 was subcloned into pcDNA5/ FRT.15 The pcDNA5/FRT plasmid containing full-length human BCRP cDNA was used as a template to generate all the BCRP mutants using PCR mutagenesis as previously described.15 The following forward primers were used for mutagenesis: P392A (5'-AAC TTG CTG GGT AAT GCC CAG GCC TCT ATA GCT C-3'), P480A (5'-CTG TTA TCT GAT TTA TTA GCC ATG AGG ATG TTA CCA AG-3'), P485A (5'-CCC ATG AGG ATG TTA GCA AGT ATT ATA TTT ACC TGT ATA G-3'), P501A (5'-CAT GTT AGG ATT GAA GGC AAA GGC AGA TGC CTT C-3'), P574A (5'-CAG TAC TTC AGC ATT GCA CGA TAT GGA TTT ACG-3'), and P623A (5'-GGC ATC GAT CTC TCA GCC TGG GGC TTG TGG AAG AAT-3'). Login to comment
104 The estimated relative cell surface expression levels of wild-type and mutant BCRP based on the differences in median fluorescence between 5D3 and IgG2b control incubations were 100 ± 22, 108 ± 4, 89 ± 1, 139 ± 32, 75 ± 16, 76 ± 9, and 114 ± 0.7% for three independent determinations for wild-type BCRP, P392A, P480A, P485A, P501A, P574A, and P623A, respectively. Login to comment
129 The pcDNA5 vector control, wild-type BCRP, P392A, P480A, P485A, P501A, P574A, and P623A are indicated by P, WT, 392, 480, 485, 501, 574, and 623, respectively. Login to comment
132 Drug Resistance Profile of Wild-Type and Mutant BCRPa MX SN-38 Dox Rho123 IC50 (nM) RR IC50 (nM) RR IC50 (nM) RR IC50 (nM) RR pcDNA5/FRT 5.6 ± 0.8 - 1.7 ± 0.1 - 33.1 ± 2.2 - 4218 ± 400.0 - wild-type BCRP 51.5 ± 8.5 9.2 30.3 ± 2.0 17.8 40.9 ± 6.7 1.2 4446 ± 261.5 1.1 P392A 24.6 ± 3.8 4.4* 13.1 ± 1.0 7.7* 34.8 ± 1.7 1.1 5326 ± 414.1 1.3 P480A 69.4 ± 10.5 12.4 37.8 ± 1.5 22.2 29.0 ± 4.0 0.9 5107 ± 272.7 1.2 P485A 38.5 ± 7.0 6.9 15.9 ± 2.6 9.4* 41.8 ± 5.3 1.3 3237 ± 199.5 0.8 P501A 40.9 ± 14.6 7.3 27.5 ± 2.4 16.2 23.2 ± 3.8 0.7 4480 ± 816.4 1.1 P574A 49.6 ± 12.5 8.9 32.5 ± 2.6 19.1 29.6 ± 3.5 0.9 5320 ± 419.8 1.3 P623A 68.4 ± 14.4 12.2 36.8 ± 2.8 21.6 37.0 ± 8.8 1.1 3302 ± 388.1 0.8 a The relative resistance (RR) values represent the relative levels of resistance of the mutants compared to that of wild-type BCRP and were calculated by dividing the IC50 values of wild-type and mutant BCRP by the IC50 values of the vector control. Login to comment