ABCMdb

ABCC7 p.Val1129Cys

CF databases:	c.3386T>G , p.Val1129Gly (CFTR1) ? , Name in accordance with the standard nomenclature guidelines (HGVS): c.3386T>G or p.Val1129Gly
Predicted by SNAP2:	A: N (61%), C: N (78%), D: D (75%), E: D (66%), F: N (53%), G: D (63%), H: D (71%), I: N (93%), K: D (75%), L: N (57%), M: N (66%), N: D (66%), P: D (66%), Q: D (66%), R: D (80%), S: N (53%), T: N (61%), W: D (75%), Y: D (66%),
Predicted by PROVEAN:	A: D, C: D, D: D, E: D, F: D, G: D, H: D, I: N, K: D, L: N, M: N, N: D, P: D, Q: D, R: D, S: D, T: D, W: D, Y: D,

[switch to compact view]
Comments [show]

None has been submitted yet.

Publications
[hide] Novel residues lining the CFTR chloride channel po... J Membr Biol. 2009 Apr;228(3):151-64. Epub 2009 Apr 19. Fatehi M, Linsdell P
Novel residues lining the CFTR chloride channel pore identified by functional modification of introduced cysteines.
J Membr Biol. 2009 Apr;228(3):151-64. Epub 2009 Apr 19., [PMID:19381710]

Abstract [show]
Substituted cysteine accessibility mutagenesis (SCAM) has been used widely to identify pore-lining amino acid side chains in ion channel proteins. However, functional effects on permeation and gating can be difficult to separate, leading to uncertainty concerning the location of reactive cysteine side chains. We have combined SCAM with investigation of the charge-dependent effects of methanethiosulfonate (MTS) reagents on the functional permeation properties of cystic fibrosis transmembrane conductance regulator (CFTR) Cl(-) channels. We find that cysteines substituted for seven out of 21 continuous amino acids in the eleventh and twelfth transmembrane (TM) regions can be modified by external application of positively charged [2-(trimethylammonium)ethyl] MTS bromide (MTSET) and negatively charged sodium [2-sulfonatoethyl] MTS (MTSES). Modification of these cysteines leads to changes in the open channel current-voltage relationship at both the macroscopic and single-channel current levels that reflect specific, charge-dependent effects on the rate of Cl(-) permeation through the channel from the external solution. This approach therefore identifies amino acid side chains that lie within the permeation pathway. Cysteine mutagenesis of pore-lining residues also affects intrapore anion binding and anion selectivity, giving more information regarding the roles of these residues. Our results demonstrate a straightforward method of screening for pore-lining amino acids in ion channels. We suggest that TM11 contributes to the CFTR pore and that the extracellular loop between TMs 11 and 12 lies close to the outer mouth of the pore.

Comments [show]

None has been submitted yet.

Sentences [show]
No. Sentence Comment
71 As described previously for modification of cysteines introduced into TM6 (Fatehi and Linsdell 2008) and the extracellular loop between TMs 1 and 2 (Zhou et al. 2008), MTSET and MTSES altered the IREL-V shape in S1118C, T1121C, T1122C, G1127C, V1129C, I1131C and I1132C. Login to comment
72 Of 21 cysteine mutants studied, only six significantly altered I-V relationship shape in the absence of external MTS reagents (Fig. 3a), with S1118C, T1121C, T1122C, G1127C and A1136C all causing significant inward rectification and V1129C showing outward rectification. Login to comment
83 Only one mutant-V1129C-significantly affected the magnitude of unitary currents at hyperpolarized voltages (Figs. 4, 5a), giving a decrease in unitary current amplitude of *12% at -80 mV (Fig. 5a). Login to comment
84 Unitary currents at depolarized voltages were significantly decreased in S1118C, T1121C, T1122C and G1127C and significantly increased in V1129C (Fig. 5b). Login to comment
85 This resulted in changes in the shape of the i-V relationship, causing inward rectification in the case of S1118C, T1121C, T1122C and G1127C and outward rectification in the case of V1129C (Figs. 4b, 5c). Login to comment
91 Indeed, changes in unitary current amplitude were observed in S1118C, T1121C, T1122C, G1127C, V1129C, I1131C and I1132C, but not wild-type, when MTS reagents were included in the pipette solution (Fig. 6). Login to comment
119 In contrast, the other three mutations (V1129C, I1131C, I1132C) led to no change or even a slight increase in unitary current amplitude (Fig. 5b) and more minor effects of MTS modification, resulting in no change or a small decrease in amplitude with MTSES and increases in amplitude to levels above wild-type with MTSET (Fig. 9b). Login to comment
124 Under these conditions, SCN- block was significantly strengthened in I1132C (at hyperpolarized and depolarized voltages), S1118C (at hyperpolarized voltages), T1121C and V1129C (at depolarized voltages) and I1131C (at very depolarized voltages only) Fig. 4 Single-channel currents carried by cysteine mutant forms of CFTR. Login to comment
125 a Example single-channel currents carried by wild-type, S1118C, T1121C, T1122C and V1129C, at membrane potentials of ?60 (top) and -60 (bottom) mV. Login to comment
133 Under these conditions, SCN- permeability was significantly increased in S1118C and (to a lesser extent) T1122C and G1127C and unaltered in T1121C, V1129C, I1131C and I1132C (Fig. 11). Login to comment
158 Of the seven mutants that were functionally modified by MTS reagents, five (S1118C, T1121C, T1122C, G1127C, V1129C) also showed significantly altered unitary current amplitude in the absence of MTS modification (Figs. 4, 5). Login to comment
161 a S1118C (d), T1121C (j), T1122C (), G1127C (h); b V1129C (m), I1131C (r), I1132C (.). Login to comment
183 We speculate that one group of reactive mutants (S1118C, T1121C, T1122C, G1127C) is located relatively deep in the pore from the outside and that the other (V1129C, Fig. 11 Thiocyanate permeability of mutants. Login to comment
191 Chloride conductance was further reduced by MTSES modification at these sites, indicating the detrimental effect of depositing a negative charge within the permeation pathway. Cysteine substitution at the outer mouth of the pore (V1129C, I1131C, I1132C) (Fig. 9b) had somewhat different effects. Login to comment