ABCC7 p.Leu346Arg
| ClinVar: |
c.1037T>C
,
p.Leu346Pro
?
, not provided
|
| CF databases: |
c.1037T>C
,
p.Leu346Pro
(CFTR1)
?
,
|
| Predicted by SNAP2: | A: D (91%), C: D (91%), D: D (95%), E: D (95%), F: D (95%), G: D (95%), H: D (95%), I: D (85%), K: D (95%), M: D (91%), N: D (95%), P: D (75%), Q: D (91%), R: D (95%), S: D (95%), T: D (95%), V: D (75%), W: D (95%), Y: D (95%), |
| Predicted by PROVEAN: | A: D, C: D, D: D, E: D, F: N, G: D, H: D, I: N, K: D, M: N, N: D, P: D, Q: D, R: D, S: D, T: D, V: N, W: D, Y: D, |
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[hide] Corrector VX-809 stabilizes the first transmembran... Biochem Pharmacol. 2013 Sep 1;86(5):612-9. doi: 10.1016/j.bcp.2013.06.028. Epub 2013 Jul 5. Loo TW, Bartlett MC, Clarke DM
Corrector VX-809 stabilizes the first transmembrane domain of CFTR.
Biochem Pharmacol. 2013 Sep 1;86(5):612-9. doi: 10.1016/j.bcp.2013.06.028. Epub 2013 Jul 5., [PMID:23835419]
Abstract [show]
Processing mutations that inhibit folding and trafficking of CFTR are the main cause of cystic fibrosis (CF). A potential CF therapy would be to repair CFTR processing mutants. It has been demonstrated that processing mutants of P-glycoprotein (P-gp), CFTR's sister protein, can be efficiently repaired by a drug-rescue mechanism. Many arginine suppressors that mimic drug-rescue have been identified in the P-gp transmembrane (TM) domains (TMDs) that rescue by forming hydrogen bonds with residues in adjacent helices to promote packing of the TM segments. To test if CFTR mutants could be repaired by a drug-rescue mechanism, we used truncation mutants to test if corrector VX-809 interacted with the TMDs. VX-809 was selected for study because it is specific for CFTR, it is the most effective corrector identified to date, but it has limited clinical benefit. Identification of the VX-809 target domain will help to develop correctors with improved clinical benefits. It was found that VX-809 rescued truncation mutants lacking the NBD2 and R domains. When the remaining domains (TMD1, NBD1, TMD2) were expressed as separate polypeptides, VX-809 only increased the stability of TMD1. We then performed arginine mutagenesis on TM6 in TMD1. Although the results showed that TM6 had distinct lipid and aqueous faces, CFTR was different from P-gp as no arginine promoted maturation of CFTR processing mutants. The results suggest that TMD1 contains a VX-809 binding site, but its mechanism differed from P-gp drug-rescue. We also report that V510D acts as a universal suppressor to rescue CFTR processing mutants.
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No. Sentence Comment
168 Examples of the different effects of the arginines such as no effect (I344R), small reduction in maturation (V345R), large reduction in maturation (F337R), and no maturation (L346R) are shown in Fig. 4B. The TM6 arginine mutagenesis results were projected on a helical wheel (Fig. 4C).
X
ABCC7 p.Leu346Arg 23835419:168:175
status: NEW204 (B) Examples of immunoblots of wild-type CFTR and mutants I344R, V345R, F337R, and L346R showing the various effects of arginines introduced into TM6.
X
ABCC7 p.Leu346Arg 23835419:204:83
status: NEW[hide] The cystic fibrosis V232D mutation inhibits CFTR m... Biochem Pharmacol. 2014 Mar 1;88(1):46-57. doi: 10.1016/j.bcp.2013.12.027. Epub 2014 Jan 9. Loo TW, Clarke DM
The cystic fibrosis V232D mutation inhibits CFTR maturation by disrupting a hydrophobic pocket rather than formation of aberrant interhelical hydrogen bonds.
Biochem Pharmacol. 2014 Mar 1;88(1):46-57. doi: 10.1016/j.bcp.2013.12.027. Epub 2014 Jan 9., [PMID:24412276]
Abstract [show]
Processing mutations that inhibit folding and trafficking of CFTR are the main cause of cystic fibrosis. Repair of CFTR mutants requires an understanding of the mechanisms of misfolding caused by processing mutations. Previous studies on helix-loop-helix fragments of the V232D processing mutation suggested that its mechanism was to lock transmembrane (TM) segments 3 and 4 together by a non-native hydrogen bond (Asp232(TM4)/Gln207(TM3)). Here, we performed mutational analysis to test for Asp232/Gln207 interactions in full-length CFTR. The rationale was that a V232N mutation should mimic V232D and a V232D/Q207A mutant should mature if the processing defect was caused by hydrogen bonds. We report that only Val232 mutations to charged amino acids severely blocked CFTR maturation. The V232N mutation did not mimic V232D as V232N showed 40% maturation compared to 2% for V232D. Mutation of Val232 to large nonpolar residues (Leu, Phe) had little effect. The Q207L mutation did not rescue V232D because Q207L showed about 50% maturation in the presence of corrector VX-809 while V232D/Q207A could no longer be rescued. These results suggest that V232D inhibits maturation by disrupting a hydrophobic pocket between TM segments rather than forming a non-native hydrogen bond. Disulfide cross-linking analysis of cysteines W356C(TM6) and W1145C(TM12) suggest that the V232D mutation inhibits maturation by trapping CFTR as a partially folded intermediate. Since correctors can efficiently rescue V232D CFTR, the results suggest that hydrophilic processing mutations facing a hydrophobic pocket are good candidates for rescue with pharmacological chaperones.
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No. Sentence Comment
254 Accordingly, wild-type CFTR and mutants F229R, F236R, F310R, F312R, L346R, V350R and F354R were expressed in HEK 293 cells and whole cell SDS extracts were subjected to immunoblot analysis.
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ABCC7 p.Leu346Arg 24412276:254:68
status: NEW286 (A) Whole cell SDS extracts of cells expressing wild-type (WT), F229R, F236R, F310R, F312R, L346R, V350R and F354R CFTR mutants were subjected to immunoblot analysis.
X
ABCC7 p.Leu346Arg 24412276:286:92
status: NEW