ABCG2 p.Thr82Ala
| Predicted by SNAP2: | A: D (75%), C: D (91%), D: D (95%), E: D (95%), F: D (95%), G: D (95%), H: D (95%), I: D (95%), K: D (95%), L: D (95%), M: D (91%), N: D (91%), P: D (75%), Q: D (66%), R: D (95%), S: D (80%), V: D (91%), W: D (95%), Y: D (95%), |
| Predicted by PROVEAN: | A: D, C: D, D: D, E: D, F: D, G: D, H: D, I: D, K: D, L: D, M: D, N: D, P: D, Q: D, R: D, S: D, V: D, W: D, Y: D, |
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[hide] Dominant-negative inhibition of breast cancer resi... Int J Cancer. 2002 Feb 10;97(5):626-30. Kage K, Tsukahara S, Sugiyama T, Asada S, Ishikawa E, Tsuruo T, Sugimoto Y
Dominant-negative inhibition of breast cancer resistance protein as drug efflux pump through the inhibition of S-S dependent homodimerization.
Int J Cancer. 2002 Feb 10;97(5):626-30., 2002-02-10 [PMID:11807788]
Abstract [show]
Breast cancer resistance protein (BCRP) is a half-molecule ABC transporter highly expressed in mitoxantrone-resistant cells. In our study we established PA317 transfectants expressing Myc-tagged BCRP (MycBCRP) or HA-tagged BCRP (HABCRP). The exogenous BCRP protein migrated as a 70-kDa protein in SDS-PAGE under reducing condition, but migrated as a 140-kDa complex in the absence of reducing agents. The 140-kDa BCRP complex was heat-stable but dissociated into 70-kDa BCRP with the addition of 2-mercaptoethanol. The 140-kDa BCRP complex was immunoprecipitated with anti-Myc antibody from the lysates of PA317 cells double-transfected with MycBCRP and HABCRP. The 140-kDa complex reacted with anti-HA and anti-BCRP antibodies and after the addition of reducing agents, a 70-kDa protein reacting with anti-Myc, anti-HA and anti-BCRP antibodies was detected. These results clearly indicate that BCRP forms a homodimer bridged by disulfide bonds. To assess the possible dominant-negative inhibition of BCRP drug efflux pump, various mutant BCRP cDNAs were isolated by PCR mutagenesis. First, mutant BCRP cDNAs were introduced to parental PA317 cells and tested for their function as drug-resistance genes. Next, inactive BCRP cDNA clones were introduced to MycBCRP-transfected cells and tested for the ability to lower drug resistance. Among the 8 inactive mutant cDNA clones tested, HABCRP cDNA clone 15 with an amino acid change from Leu to Pro at residue 554 in the fifth transmembrane domain of BCRP partially reversed the drug resistance of MycBCRP-transfected cells. These results suggest that homodimer formation is essential for BCRP drug resistance, implicating this dominant-negative inhibition as a new strategy to circumvent drug resistance.
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No. Sentence Comment
151 to Ala and Tyr-605 to Cys), HABCRP-37 (Thr-82 to Ala) or HABCRP-74 (Ser-25 to Pro, Arg-309 to Gly and Ala-632 to Val), also expressed mutant BCRP protein, but cells transfected with HABCRP-86 (Lys-86 to Ile) did not express BCRP protein and therefore exhibited no drug resistance.
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ABCG2 p.Thr82Ala 11807788:151:39
status: VERIFIED[hide] Towards understanding the mechanism of action of t... J Mol Graph Model. 2007 Mar;25(6):837-51. Epub 2006 Aug 30. Li YF, Polgar O, Okada M, Esser L, Bates SE, Xia D
Towards understanding the mechanism of action of the multidrug resistance-linked half-ABC transporter ABCG2: a molecular modeling study.
J Mol Graph Model. 2007 Mar;25(6):837-51. Epub 2006 Aug 30., [PMID:17027309]
Abstract [show]
The ATP-binding cassette protein ABCG2 is a member of a broad family of ABC transporters with potential clinical importance as a mediator of multidrug resistance. We carried out a homology and knowledge-based, and mutationally improved molecular modeling study to establish a much needed structural framework for the protein, which could serve as guidance for further genetic, biochemical, and structural analyses. Based on homology with known structures of both full-length and nucleotide-binding domains (NBD) of ABC transporters and structural knowledge of integral membrane proteins, an initial model of ABCG2 was established. Subsequent refinement to conform to the lipophilic index distributions in the transmembrane domain (TMD) and to the results of site-directed mutagenesis experiments led to an improved model. The complete ABCG2 model consists of two identical subunits facing each other in a closed conformation. The dimeric interface in the nucleotide-binding domain (NBD) involves a characteristic nucleotide sandwich and the interface in the TMD consists of the TM helices 1-3 of one subunit and the helices 5 and 6 of the other. The interface between the NBD and the TMD is bridged by the conserved structural motif between TM2 and TM3, the intracellular domain 1 (ICD1), and the terminal beta-strand (S6) of the central beta-sheet in the NBD. The apparent flexibility of the ICD1 may play a role in transmitting conformational changes from the NBD to the TMD or from the TMD to the NBD.
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No. Sentence Comment
109 Mutations T82A, K86M, and K86I [42,43] are part of the Walker A motif; all lead to loss of transport activity.
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ABCG2 p.Thr82Ala 17027309:109:10
status: VERIFIED110 The T82A mutation results in the possible loss of interaction with residue R193 in the neighboring LSGGQ motif, potentially affecting dimer assembly.
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ABCG2 p.Thr82Ala 17027309:110:4
status: VERIFIED