ABCC7 p.Glu92Cys
| ClinVar: |
c.274G>T
,
p.Glu92*
D
, Pathogenic
c.276A>T , p.Glu92Asp ? , not provided c.274G>A , p.Glu92Lys D , Pathogenic |
| CF databases: |
c.274G>T
,
p.Glu92*
D
, CF-causing
c.274G>A , p.Glu92Lys D , CF-causing ; CFTR1: E92K was detected in one Spanish chromosome out of 100 non-[delta]F508 chromosomes studied. The mutation on the other chromosome of this patient is unknown, but has the haplotype C/D. The mutation has been detected by SSCP analysis of exon 4 PCR product using intronic primers. Th ebase change has been confirmed after recovering the mutated strand from the SSCP gel, purified and directly sequenced using an automatic sequencer. c.276A>T , p.Glu92Asp (CFTR1) ? , The patient carries two other mutations: 3849+10kbC>T and R668C (2134C>T). Although segregation analysis was not performed, we suggest the putative 3849+10kbC>T;R668C/E92D compound genotype in the patient, as we already found the complex allele 3849+10kbC>T;R668C in another patient. Residue E92 is conserved between species but not in other proteins of the CFTR family, where Asp can be found instead. A mild splicing effect of the mutation is also possible. |
| Predicted by SNAP2: | A: D (91%), C: D (95%), D: D (91%), F: D (95%), G: D (95%), H: D (95%), I: D (95%), K: N (53%), L: D (95%), M: D (91%), N: D (95%), P: D (95%), Q: D (85%), R: D (95%), S: D (95%), T: D (95%), V: D (95%), W: D (95%), Y: D (95%), |
| Predicted by PROVEAN: | A: D, C: D, D: N, F: D, G: D, H: D, I: D, K: D, L: D, M: D, N: N, P: D, Q: N, R: D, S: N, T: D, V: D, W: D, Y: D, |
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[hide] Alignment of transmembrane regions in the cystic f... J Gen Physiol. 2011 Aug;138(2):165-78. Epub 2011 Jul 11. Wang W, El Hiani Y, Linsdell P
Alignment of transmembrane regions in the cystic fibrosis transmembrane conductance regulator chloride channel pore.
J Gen Physiol. 2011 Aug;138(2):165-78. Epub 2011 Jul 11., [PMID:21746847]
Abstract [show]
Different transmembrane (TM) alpha helices are known to line the pore of the cystic fibrosis TM conductance regulator (CFTR) Cl(-) channel. However, the relative alignment of these TMs in the three-dimensional structure of the pore is not known. We have used patch-clamp recording to investigate the accessibility of cytoplasmically applied cysteine-reactive reagents to cysteines introduced along the length of the pore-lining first TM (TM1) of a cysteine-less variant of CFTR. We find that methanethiosulfonate (MTS) reagents irreversibly modify cysteines substituted for TM1 residues K95, Q98, P99, and L102 when applied to the cytoplasmic side of open channels. Residues closer to the intracellular end of TM1 (Y84-T94) were not apparently modified by MTS reagents, suggesting that this part of TM1 does not line the pore. None of the internal MTS reagent-reactive cysteines was modified by extracellular [2-(trimethylammonium)ethyl] MTS. Only K95C, closest to the putative intracellular end of TM1, was apparently modified by intracellular [2-sulfonatoethyl] MTS before channel activation. Comparison of these results with recent work on CFTR-TM6 suggests a relative alignment of these two important TMs along the axis of the pore. This alignment was tested experimentally by formation of disulfide bridges between pairs of cysteines introduced into these two TMs. Currents carried by the double mutants K95C/I344C and Q98C/I344C, but not by the corresponding single-site mutants, were inhibited by the oxidizing agent copper(II)-o-phenanthroline. This inhibition was irreversible on washing but could be reversed by the reducing agent dithiothreitol, suggesting disulfide bond formation between the introduced cysteine side chains. These results allow us to develop a model of the relative positions, functional contributions, and alignment of two important TMs lining the CFTR pore. Such functional information is necessary to understand and interpret the three-dimensional structure of the pore.
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No. Sentence Comment
66 The one exception was E92C, which failed to generate any measureable current, even after multiple attempts with two independently constructed mutant cDNAs.
X
ABCC7 p.Glu92Cys 21746847:66:22
status: NEW118 Note that no currents were recorded from patches excised from cells transfected with E92C cDNA (see Results).
X
ABCC7 p.Glu92Cys 21746847:118:85
status: NEW[hide] Cysteine scanning of CFTR's first transmembrane se... Biophys J. 2013 Feb 19;104(4):786-97. doi: 10.1016/j.bpj.2012.12.048. Gao X, Bai Y, Hwang TC
Cysteine scanning of CFTR's first transmembrane segment reveals its plausible roles in gating and permeation.
Biophys J. 2013 Feb 19;104(4):786-97. doi: 10.1016/j.bpj.2012.12.048., [PMID:23442957]
Abstract [show]
Previous cysteine scanning studies of the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel have identified several transmembrane segments (TMs), including TM1, 3, 6, 9, and 12, as structural components of the pore. Some of these TMs such as TM6 and 12 may also be involved in gating conformational changes. However, recent results on TM1 seem puzzling in that the observed reactive pattern was quite different from those seen with TM6 and 12. In addition, whether TM1 also plays a role in gating motions remains largely unknown. Here, we investigated CFTR's TM1 by applying methanethiosulfonate (MTS) reagents from both cytoplasmic and extracellular sides of the membrane. Our experiments identified four positive positions, E92, K95, Q98, and L102, when the negatively charged MTSES was applied from the cytoplasmic side. Intriguingly, these four residues reside in the extracellular half of TM1 in previously defined CFTR topology; we thus extended our scanning to residues located extracellularly to L102. We found that cysteines introduced into positions 106, 107, and 109 indeed react with extracellularly applied MTS probes, but not to intracellularly applied reagents. Interestingly, whole-cell A107C-CFTR currents were very sensitive to changes of bath pH as if the introduced cysteine assumes an altered pKa-like T338C in TM6. These findings lead us to propose a revised topology for CFTR's TM1 that spans at least from E92 to Y109. Additionally, side-dependent modifications of these positions indicate a narrow region (L102-I106) that prevents MTS reagents from penetrating the pore, a picture similar to what has been reported for TM6. Moreover, modifications of K95C, Q98C, and L102C exhibit strong state dependency with negligible modification when the channel is closed, suggesting a significant rearrangement of TM1 during CFTR's gating cycle. The structural implications of these findings are discussed in light of the crystal structures of ABC transporters and homology models of CFTR.
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None has been submitted yet.
No. Sentence Comment
83 We could only obtain microscopic current with E92C-CFTR probably due to a poor expression, but the application of MTSES decreased the single-channel amplitude of this construct (see below).
X
ABCC7 p.Glu92Cys 23442957:83:46
status: NEW165 State-dependent modification of E92C-, K95C-, Q98C-, and L102C-CFTR The observation that MTSET modification of Q98C and L102C alters CFTR gating suggests that TM1 indeed participates in gating motions of CFTR.
X
ABCC7 p.Glu92Cys 23442957:165:32
status: NEW171 As this series of experiments requires macroscopic currents, we could not test the E92C mutants, which express poorly (see Discussion for details).
X
ABCC7 p.Glu92Cys 23442957:171:83
status: NEW250 Although we were not able to measure the modification rate for E92C because of poor expression, in five patches yielding microscopic current, MTSES appears to modify the introduced cysteine when the channel is opened (see Fig. S7).
X
ABCC7 p.Glu92Cys 23442957:250:63
status: NEW