ABCMdb

ABCC7 p.Lys335Ala

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Publications

PMID: 11557589 [PubMed] McCarty NA et al: "Identification of a region of strong discrimination in the pore of CFTR."

No. Sentence Comment

61 Mutants K335A, T338E, and T1134E were prepared with the QuickChange protocol (Stratagene, La Jolla, CA). Login to comment
143 Relative permeabilities for WT and mutant CFTRs for monovalent anions CFTR n NO3 Br SCN I ClO4 Acetate Isethionate Glutamate Gluconate WT 16 1.35Ϯ0.01 1.19Ϯ0.02 2.42Ϯ0.06 0.36Ϯ0.01 0.10Ϯ0.01 0.15Ϯ0.00* 0.24Ϯ0.01 0.24Ϯ0.01 0.18Ϯ0.01 K335A 5 1.35Ϯ0.01 1.36Ϯ0.03 3.10Ϯ0.11† 0.75Ϯ0.02† 0.12Ϯ0.01 0.06Ϯ0.01† 0.07Ϯ0.01† 0.07Ϯ0.01† 0.08Ϯ0.01† K335F 7 1.51Ϯ0.03† 1.36Ϯ0.02† 2.73Ϯ0.14 0.99Ϯ0.03† 0.20Ϯ0.02† 0.13Ϯ0.01 0.18Ϯ0.03 0.30Ϯ0.02 0.20Ϯ0.02 K335E 5 1.24Ϯ0.04 1.17Ϯ0.02 2.60Ϯ0.06 1.10Ϯ0.03† 0.23Ϯ0.01† 0.10Ϯ0.01† 0.11Ϯ0.01† 0.10Ϯ0.01† 0.11Ϯ0.01† T338A 5 1.74Ϯ0.07† 1.59Ϯ0.02† 4.35Ϯ0.24† 2.56Ϯ0.13† 1.84Ϯ0.08† 0.07Ϯ0.01† 0.06Ϯ0.01† 0.08Ϯ0.01† 0.08Ϯ0.01† T338E 3 3.65Ϯ0.19† 1.94Ϯ0.04† 4.29Ϯ0.13† 2.41Ϯ0.24† 1.18Ϯ0.06† 0.16Ϯ0.03 0.37Ϯ0.05† 0.36Ϯ0.01† 0.22Ϯ0.03 T339A 5 1.47Ϯ0.01 1.29Ϯ0.03 2.65Ϯ0.06 0.57Ϯ0.02† 0.24Ϯ0.04 0.10Ϯ0.02 0.19Ϯ0.02 0.18Ϯ0.01 0.15Ϯ0.01 S341A 6 1.91Ϯ0.02† 1.42Ϯ0.01† 3.10Ϯ0.09† 0.59Ϯ0.00*† 0.09Ϯ0.00* 0.11Ϯ0.01† 0.12Ϯ0.00*† 0.11Ϯ0.00*† 0.12Ϯ0.00*† S341E 12 2.01Ϯ0.10† 1.46Ϯ0.05† 2.81Ϯ0.18 0.84Ϯ0.00*† 0.31Ϯ0.03† 0.20Ϯ0.01 0.23Ϯ0.02 0.19Ϯ0.01 0.19Ϯ0.02 S341T 5 1.81Ϯ0.05† 1.39Ϯ0.03 3.15Ϯ0.15† 0.41Ϯ0.01 0.07Ϯ0.00* 0.05Ϯ0.00*† 0.06Ϯ0.00*† 0.03Ϯ0.01† 0.06Ϯ0.01† T1134A 6 1.43Ϯ0.02 1.30Ϯ0.02 2.66Ϯ0.02 0.46Ϯ0.00*† 0.06Ϯ0.00*† 0.08Ϯ0.01† 0.10Ϯ0.01† 0.11Ϯ0.01† 0.10Ϯ0.00*† T1134F 5 1.31Ϯ0.07 1.17Ϯ0.05 2.50Ϯ0.10 0.63Ϯ0.01† 0.08Ϯ0.00* 0.13Ϯ0.01 0.09Ϯ0.01† 0.18Ϯ0.02 0.13Ϯ0.01 T1134E 4 1.68Ϯ0.02† 1.39Ϯ0.05† 2.37Ϯ0.18 0.19Ϯ0.03† 0.20Ϯ0.03 0.06Ϯ0.01† 0.09Ϯ0.01† 0.08Ϯ0.01† 0.10Ϯ0.01† Values are means Ϯ SE with only data from the hyperpolarizing ramp protocol; n, no. of oocytes. Relative permeability, permeability of anion x to that of Cl. Anions are listed in order of increasing ionic radius. Login to comment
167 Selectivity sequences for WT and mutant CFTRs CFTR Selectivity Sequence by Relative Permeability WT SCNϾϾNO3 ϾBrϾClϾϾIϾisethionateϭglutamateϾgluconateϭacetateϾClO4 K335A SCNϾϾBrϭNO3 ϾClϾIϾϾClO4 Ͼgluconateϭisethionateϭglutamateϭacetate K335F SCNϾϾNO3 ϾBrϾClϭIϾϾglutamateϾgluconateϭClO4 ϭisethionateϾacetate K335E SCNϾϾNO3 ϾBrϭIϾClϾϾClO4 Ͼgluconateϭisethionateϭglutamateϭacetate T338A SCNϾϾIϾϾClO4 ϭNO3 ϾBrϾClϾϾgluconateϭisethionateϭglutamateϭacetate T338E SCNϾNO3 ϾIϾBrϾClO4 ϾClϾϾisethionateϭglutamateϾgluconateϭacetate T339A SCNϾϾNO3 ϾBrϾClϾϾIϾϾClO4 ϭisethionateϭglutamateϭgluconateϾacetate S341A SCNϾNO3 ϾBrϾClϾϾIϾϾgluconateϭisethionateϭglutamateϭacetateϭClO4 S341E SCNϾNO3 ϾBrϾClϾIϾϾClO4 Ͼisethionateϭacetateϭglutamateϭgluconate S341T SCNϾϾNO3 ϾBrϾClϾϾIϾϾClO4 ϭisethionateϭgluconateϭacetateϭglutamate T1134A SCNϾϾNO3 ϾBrϾClϾϾIϾϾglutamateϭisethionateϭgluconateϭacetateϭClO4 T1134F SCNϾϾNO3 ϾBrϾClϾϾIϾϾglutamateϾacetateϭgluconateϾisethionateϭClO4 T1134E SCNϾNO3 ϾBrϾClϾϾClO4 ϭIϾgluconateϭisethionateϭglutamateϭacetate L856 A REGION OF STRONG DISCRIMINATION IN THE CFTR PORE AJP-Lung Cell Mol Physiol • VOL 281 • OCTOBER 2001 • www.ajplung.org out propagation to distant sites. Login to comment
191 Relative conductances for WT and mutant CFTRs for monovalent anions CFTR n NO3 Br SCN I ClO4 Acetate Isethionate Glutamate Gluconate WT 16 0.87Ϯ0.01 0.77Ϯ0.01 0.18Ϯ0.01 0.25Ϯ0.01 0.23Ϯ0.01 0.55Ϯ0.01 0.50Ϯ0.01 0.57Ϯ0.02 0.56Ϯ0.02 K335A 5 0.88Ϯ0.04 0.77Ϯ0.02 0.30Ϯ0.02† 0.35Ϯ0.02 0.24Ϯ0.02 0.33Ϯ0.01† 0.32Ϯ0.02† 0.37Ϯ0.02† 0.38Ϯ0.02† K335F 7 1.21Ϯ0.05† 0.87Ϯ0.02† 0.55Ϯ0.02† 0.36Ϯ0.01† 0.19Ϯ0.01 0.34Ϯ0.01† 0.34Ϯ0.01† 0.41Ϯ0.01† 0.37Ϯ0.01† K335E 5 1.16Ϯ0.05† 0.91Ϯ0.02† 0.59Ϯ0.02† 0.51Ϯ0.02† 0.28Ϯ0.01 0.22Ϯ0.01† 0.25Ϯ0.01† 0.22Ϯ0.01† 0.24Ϯ0.01† T338A 5 1.20Ϯ0.13† 1.03Ϯ0.06† 0.98Ϯ0.12† 0.82Ϯ0.02† 0.50Ϯ0.04† 0.18Ϯ0.05† 0.08Ϯ0.01† 0.31Ϯ0.05† 0.29Ϯ0.05† T338E 3 3.66Ϯ0.36† 1.53Ϯ0.09† 1.80Ϯ0.12† 1.39Ϯ0.11† 0.87Ϯ0.03† 0.36Ϯ0.04† 0.56Ϯ0.17 0.44Ϯ0.03† 0.48Ϯ0.03† T339A 5 1.01Ϯ0.02† 0.77Ϯ0.03 0.22Ϯ0.01 0.31Ϯ0.03 0.23Ϯ0.01 0.38Ϯ0.02† 0.48Ϯ0.01 0.48Ϯ0.01 0.52Ϯ0.01 S341A 6 1.67Ϯ0.01† 1.08Ϯ0.01† 0.63Ϯ0.03† 0.26Ϯ0.00* 0.15Ϯ0.01† 0.63Ϯ0.01† 0.54Ϯ0.02 0.63Ϯ0.01 0.63Ϯ0.01 S341E 12 1.74Ϯ0.11† 1.14Ϯ0.02† 1.81Ϯ0.06† 0.48Ϯ0.01† 0.35Ϯ0.02† 0.28Ϯ0.01† 0.69Ϯ0.02† 0.65Ϯ0.01† 0.68Ϯ0.01† S341T 5 0.85Ϯ0.02 0.82Ϯ0.01 0.29Ϯ0.01† 0.22Ϯ0.01 0.13Ϯ0.01† 0.48Ϯ0.01 0.45Ϯ0.02 0.43Ϯ0.02 0.55Ϯ0.01 T1134A 6 0.83Ϯ0.02 0.78Ϯ0.01 0.24Ϯ0.01† 0.21Ϯ0.01 0.09Ϯ0.01† 0.39Ϯ0.01† 0.38Ϯ0.01† 0.39Ϯ0.01† 0.40Ϯ0.01 T1134F 5 0.68Ϯ0.03† 0.69Ϯ0.03† 0.36Ϯ0.01† 0.07Ϯ0.01† 0.16Ϯ0.01 0.48Ϯ0.02 0.30Ϯ0.02† 0.22Ϯ0.01† 0.32Ϯ0.02† T1134E 4 0.99Ϯ0.02† 1.00Ϯ0.02† 0.50Ϯ0.02† 0.20Ϯ0.03 0.26Ϯ0.02 0.32Ϯ0.03† 0.34Ϯ0.01† 0.34Ϯ0.03† 0.34Ϯ0.03† Values are means Ϯ SE with only data from the hyperpolarizing ramp protocol; n, no. of oocytes. Relative conductance, conductance of anion x to that of Cl. Anions are listed in order of increasing ionic radius. Login to comment
197 The shape of the I-V curve between -80 and ϩ60 mV was not affected by the K335A, T338A, T339A, or T1134A mutations, whereas S341A CFTR exhibited less outward rectification than WT CFTR. Login to comment
203 K335A and T1134A CFTR exhibited decreased Gx/GCl values for most anions, with radii as large as or larger than acetate. Login to comment
204 However, neither Px/PCl nor Gx/GCl values for the smallest anions (NO3 - and Br- ) were altered in K335A CFTR or T1134A CFTR compared with WT CFTR. Login to comment
213 Vrev Cl in ND96 bath solution for WT and mutant CFTRs CFTR n Vrev Cl WT 16 -21.24Ϯ0.59 K335A 5 -22.12Ϯ0.35 K335F 7 -21.92Ϯ0.90 K335E 5 -22.88Ϯ0.36 T338A 5 -26.97Ϯ0.79* T338E 3 -20.58Ϯ1.07 T339A 5 -22.21Ϯ0.98 S341A 6 -21.21Ϯ0.56 S341E 12 -28.77Ϯ1.36* S341T 5 -26.62Ϯ1.43* T1134A 6 -28.33Ϯ1.23* T1134F 5 -19.74Ϯ0.73 T1134E 4 -27.54Ϯ1.27* Values are means Ϯ SE; n, no. of oocytes. Login to comment
217 At K335, Gx/GCl values for all small anions were increased in K335F CFTR compared with K335A CFTR, whereas Px/PCl values for these anions were not affected by the bulky side chain. Login to comment
268 Px/PCl and Gx/GCl values for each anion x in each mutant were calculated for T1134A, K335A, T338A, T339A, and S341A CFTRs and normalized to Px/PCl and Gx/GCl values for WT CFTR. Login to comment
316 The overall discriminating power was approximately the same for WT, K335A, T339A, and T1134A CFTR. Login to comment
378 When the alanine in K335A CFTR was replaced by the bulkier phenylalanine, the effects on anion selectivity were greater (Tables 2 and 4). Login to comment
388 Selectivity between Cl- and the divalent anion S2O3 2CFTR n GS2O3/GCl WT 16 0.39Ϯ0.01 K335A 5 0.37Ϯ0.01 K335F 7 0.39Ϯ0.01 K335E 5 0.34Ϯ0.01* T338A 5 0.38Ϯ0.01 T338E 3 0.70Ϯ0.08* T339A 5 0.39Ϯ0.02 S341A 6 0.27Ϯ0.01* S341E 12 0.54Ϯ0.01* S341T 5 0.38Ϯ0.01 T1134A 6 0.34Ϯ0.02 T1134F 5 0.33Ϯ0.01* T1134E 4 0.44Ϯ0.05 Values are means Ϯ SE; n, no. of oocytes. Login to comment
464 However, our data show that mutations K335A and T1134A had nearly identical effects on selectivity patterns between large and small anions, as if these amino acids occupy nearly homologous positions in TM6 and TM12. Login to comment

PMID: 11585852 [PubMed] Smith SS et al: "CFTR: covalent and noncovalent modification suggests a role for fixed charges in anion conduction."

No. Sentence Comment

341 However, for two mutants, R334H and K335A, the RR value clearly deviated significantly from that predicted by the general trend. Login to comment

PMID: 11927667 [PubMed] Gong X et al: "Molecular determinants of Au(CN)(2)(-) binding and permeability within the cystic fibrosis transmembrane conductance regulator Cl(-) channel pore."

No. Sentence Comment

12 Channel block by 100 mM Au(CN)2 _ , a measure of intrapore anion binding affinity, was significantly weakened in the CFTR mutants K335A, F337S, T338A and I344A, significantly strengthened in S341A and R352Q and unaltered in K329A. Login to comment
78 Currents carried by the CFTR mutants K329A, K335A, T338A, S341A and I344A were also stimulated an average of 2_3-fold by PPi (Fig. 2B). Login to comment
87 Comparison between different channel variants at _100 mV reveals the sensitivity to this concentration of Au(CN)2 _ is R352Q > S341A > wild-type, K329A > I344A > K335A = F337S > T338A. Login to comment
123 At this voltage, block by 100 mM Au(CN)2 _ was significantly weakened in K335A, F337S, T338A and I334A, significantly strengthened in S341A and R352Q and unaffected in K329A (Fig. 3). Login to comment
124 The sequence of relative sensitivity to block by 100 mM Au(CN)2 _ at _100 mV (R352Q > S341A > wild-type, K329A > I344A > K335A = F337S > T338A) suggests that T338 normally makes the strongest contribution to Au(CN)2 _ binding within the pore, with nearby residues K335 and F337 also making large contributions. Login to comment

PMID: 12411425 [PubMed] Gong X et al: "Mechanism of lonidamine inhibition of the CFTR chloride channel."

No. Sentence Comment

116 As shown in Figure 7a, 55 mM lonidamine inhibited currents carried by R334C, K335A, F337S, T338A and S341A-CFTR. Login to comment
118 The eect of these mutations on block by lonidamine is more clearly seen in the dose-response curves shown in Figure 7b. Fits of these mean data by equation 1 suggests a Kd (at 7100 mV) of 58.5 mM for wild-type, 65.6 mM for K335A, 90.0 mM for T338A, 186 mM for F337S, 206 mM for S341A, and 338 mM for R334C. Login to comment
120 Fitting data from individual patches with equation 2 gave similar and, except in the case of K335A, signi®cant changes in Kd(-100): wild-type 60.6+5.2 mM (n=5), K335A 63.1+7.4 mM (n=5) (P40.05), T338A 93.4+4.1 mM (n=5) (P50.002), F337S 166+18 mM (n=5) (P50.0005), S341A 169+25 mM (n=5) (P50.005), R334C 260+19 mM (n=4) (P50.00001). Login to comment
121 These same ®ts also revealed changes in the voltage dependence of block, as judged by changes in d, although this was only statistically signi®cant in the case of R334C: wild-type 0.426+0.033 (n=5), K335A 0.484+0.024 (n=5) (P40.05), T338A 0.410+0.045 (n=5) (P40.05), F337S 0.365+0.015 (n=5) (P40.05), S341A 0.285+0.061 (n=5) (P40.05), R334C 0.233+0.066 (n=4) (P50.05). Login to comment
143 (a) Example I-V relationships for R334C, K335A, F337S, T338A and S341A-CFTR, before (solid lines) and following (dotted lines) addition of 55 mM lonidamine to the intracellular solution. Login to comment
145 (b) Concentration dependence of block at 7100 mV for wild-type, R334C, K335A, F337S, T338A and S341A. Login to comment
147 Each has been ®tted by equation 1, giving Kds of 58.5 mM (wild-type), 65.6 mM (K335A), 90.0 mM (T338A), 186 mM (F337S), 206 mM (S341A) and 338 mM (R334C). Login to comment

PMID: 12679372 [PubMed] Gong X et al: "Molecular determinants and role of an anion binding site in the external mouth of the CFTR chloride channel pore."

No. Sentence Comment

40 conditions of high extracellular Cl_ concentration, Au(CN)2 _ block is weakened in the CFTR pore mutants K335A, F337S and T338A (Gong et al. 2002a), suggesting that these pore residues may contribute to lyotropic anion binding site(s) within the pore. Login to comment
60 In wild-type, K335A, F337S and T338A, high extracellular Cl_ significantly weakens Au(CN)2 _ block and (except in F337S) increases the fraction of the transmembrane electric field apparently experienced by the blocker. Login to comment
131 In contrast, mutation of other nearby TM6 residues associated with weakened Au(CN)2 _ binding (K335A, F337S, T338A) showed similar sensitivity to extracellular Cl_ concentration to that seen in wild-type (Figs 1 and 2). Login to comment

PMID: 12745925 [PubMed] Gupta J et al: "Extent of the selectivity filter conferred by the sixth transmembrane region in the CFTR chloride channel pore."

No. Sentence Comment

43 Other mutants studied (K335A, I336A, I340A), like T339V, had only minor effects (data not shown). Login to comment
44 Of eight mutants studied, only T339V was without any significant effect on anion permeability (Table 1), and five mutations (R334C, K335A, F337A, T338A, I340A) led to changes in the permeability sequence among halides (Figure 2 and Table 2). Login to comment
59 Wild type R334C K335A I336A F337A T338A T339V I340A S341A Cl 1.009/0.00 (6) 1.009/0.01 (6) 1.009/0.05 (5) 1.009/0.01 (5) 1.009/0.02 (6) 1.009/0.02 (8) 1.009/0.03 (6) 1.009/0.02 (5) 1.009/0.01 (6) Br 1.479/0.06 (6) 0.969/0.00 (5)** 1.529/0.03 (5) 1.359/0.05 (5) 0.669/0.03 (6)** 2.209/0.05 (5)** 1.829/0.24 (5) 1.409/0.09 (6) 2.459/0.20 (5)** I 0.819/0.04 (6) 0.729/0.05 (3) 1.579/0.06 (4)** 0.589/0.02 (4)* 0.389/0.15 (3)* 2.799/0.26 (7)** 0.769/0.02 (6) 1.249/0.07 (6)** 0.739/0.06 (6) F 0.119/0.01 (6) 0.099/0.01 (3) 0.139/0.02 (3) 0.079/0.01 (5) 0.409/0.02 (4)** 0.139/0.01 (6) 0.079/0.00 (5) 0.069/0.01 (5) 0.059/0.01 (6)* SCN 4.759/0.30 (6) 2.769/0.38 (6)** 3.989/0.16 (5) 3.709/0.11 (5)* 1.269/0.12 (5)** 7.509/0.29 (6)** 4.829/0.40 (5) 4.189/0.14 (7)* 10.09/1.8 (6)* Relative permeabilities for different anions present in the intracellular solution under bi-ionic conditions were calculated from macroscopic current reversal potentials according to Eq. (1) (see Experimental procedures). Login to comment
65 Wild-type R334C K335A I336A F337A T338A T339V I340A S341A Cl (G(50/G'50) 1.039/0.09 (6) 4.509/0.60 (6)** 1.399/0.09 (5)** 1.519/0.14 (5)* 1.189/0.22 (6) 1.779/0.25 (8)* 1.199/0.06 (7)* 1.419/0.11 (5)* 1.809/0.18 (5)** Cl (GCl/GCl) 1.009/0.08 (6) 1.009/0.13 (6) 1.009/0.07 (5) 1.009/0.09 (5) 1.009/0.22 (6) 1.009/0.14 (8) 1.009/0.06 (7) 1.009/0.09 (5) 1.009/0.10 (5) Br 0.649/0.05 (6) 0.329/0.02 (6)** 0.669/0.05 (5) 1.079/0.10 (5)* 0.359/0.06 (6)** 0.499/0.03 (5) 0.659/0.09 (5) 0.669/0.08 (6) 1.529/0.30 (4)* I 0.299/0.05 (6) 0.749/0.02 (3)* 0.279/0.01 (4) 0.109/0.02 (4)* 0.349/0.08 (3) 0.389/0.03 (5) 0.309/0.05 (7) 0.279/0.03 (6) 1.049/0.16 (7)** F 0.379/0.04 (6) 0.329/0.04 (3) 0.349/0.03 (3) 0.709/0.10 (4)* 0.129/0.02 (3)* 0.239/0.02 (6)* 0.509/0.10 (4) 0.309/0.02 (5) 0.519/0.07 (6) SCN 0.389/0.02 (6) 0.339/0.03 (6) 0.669/0.10 (5)* 0.279/0.02 (6)* 0.399/0.04 (5) 0.269/0.02 (5)* 0.269/0.02 (4)* 0.359/0.04 (6) 0.839/0.14 (6)* Relative conductances for different anions were calculated from the slope of the macroscopic I Á/V relationship for inward versus outward currents (see Experimental procedures). Login to comment
72 This halide selectivity sequence is changed to Eisenman sequence II in I340A, and Eisenman sequence I in both K335A and T338A (Table 2), consistent with a strengthening of lyotropic anion selectivity in these mutants. Login to comment
86 Halide permeability sequence Eisenman sequence CFTR variants I( !/Br( !/Cl( !/F( I K335A, T338A Br( !/I( !/Cl( !/F( II I340A Br( !/Cl( !/I( !/F( III wild-type, I336A, T339V, S341A Cl( !/Br( !/I( !/F( IV R334C Cl( !/Br( !/F( !/I( V F337A Sequences were derived from the relative permeabilities given in table 1. Login to comment

PMID: 14610019 [PubMed] Gong X et al: "Mutation-induced blocker permeability and multiion block of the CFTR chloride channel pore."

No. Sentence Comment

98 Block of R334C and S341A appeared somewhat weaker than for wild-type CFTR, whereas K335A and T338A showed a similar degree of block as wild-type (Fig. 5, A-C). Login to comment
145 (A) Example macroscopic currents carried by the CFTR mutants R334C, K335A, F337A, T338A, and S341A before (Control) and after addition of 300 ␮M Pt(NO2)4 2to the intracellular solution. Login to comment
147 Each plot has been fitted by Eq. 2; this provides a good fit of R334C (Kd(0) ϭ 2080 ␮M, z␦ ϭ -0.174), K335A (Kd(0) ϭ 418 ␮M, z␦ ϭ -0.317), T338A (Kd(0) ϭ 626 ␮M, z␦ ϭ -0.351) and S341A (Kd(0) ϭ 1362 ␮M, z␦ ϭ -0.249), but a poor fit of F337A. Login to comment

PMID: 15504721 [PubMed] Ge N et al: "Direct comparison of the functional roles played by different transmembrane regions in the cystic fibrosis transmembrane conductance regulator chloride channel pore."

No. Sentence Comment

77 Significant, but smaller, reductions in unitary conductance were observed in G213A, V318A, S321A, V322A, K335A, and I336A (Figs. 3 and 4). Login to comment
119 Some mutants that significantly affect both unitary conductance and Au(CN)2 - block were found to be without effect on SCN- permeability (Q98A, V318A, R334K, K335A). Login to comment

PMID: 15504728 [PubMed] Zhang ZR et al: "Determination of the functional unit of the cystic fibrosis transmembrane conductance regulator chloride channel. One polypeptide forms one pore."

No. Sentence Comment

171 This observation provided an opportunity to test directly the notion that a nearby positive charge would modify the rate of modification of the cysteine at 334 by comparing the rate of modification of R334C-CFTR with the rate of modification of R334C/K335A-CFTR (Fig. 4B). Login to comment
172 The amplitude of macroscopic current was increased 2.97 Ϯ 0.24-fold by 50 ␮M MTSETϩ in R334C/K335A-CFTR. Login to comment
174 These data are compatible with the notion that the rate of modification of a cysteine at position 334 is sensitive to the local electrostatic potential, partially determined by the amino acid at position 335, although we cannot discount the possibility that the K335A mutation altered the pore structure FIG. 3. Login to comment
190 The change in electrostatic potential due to modification of one cysteine would be expected to alter the rate of modification of the remaining cysteine, as suggested by the difference in response in R334C- and R334C/ K335A-CFTR. Login to comment
194 Outside-out macropatch experiments for mutants R334C- and R334C/K335A-CFTR. Login to comment
199 The amplitude of macroscopic current was increased by 2.3-fold upon modification by MTSETϩ in this experiment. B, representative macroscopic current of R334C/K335A-CFTR; the red line is the curve fit, with ␶ ϭ 1.1 s in this experiment. Login to comment

PMID: 18449561 [PubMed] Zhou JJ et al: "Identification of positive charges situated at the outer mouth of the CFTR chloride channel pore."

No. Sentence Comment

62 To investigate the role of charge on these residues in controlling I-V shape, neutral substitutions (R104Q, R117Q, K335A, R1128Q) were also investigated. Login to comment
91 All mutants depicted (R104Q, R117Q, K335A, R1128Q, R104E, R117E, K335E, R1128E) showed rectification ratios significantly different from wild type (asterisk P<0.05). Login to comment
116 All mutants depicted (R104Q, R117Q, K335A, R104E, R117E, K335E) significantly different from wild type (asterisk P<0.05). Login to comment
120 As shown in Fig. 8a, while Pt(NO2)4 2-induced strong inward rectification in wild type (as a result of strongly voltage-dependent current inhibition) [26], this effect was less marked in R104Q, K335A, and R1128Q. Login to comment
122 Considering the data at +80 mV, where the inhibitory effects of Pt(NO2)4 2- are strongest, suggests that Pt(NO2)4 2- inhibition is significantly weakened in R104Q, K335A, and (to a lesser extent) R1128Q but not significantly altered in K114C, R117Q, K329A, K829Q, or R899Q (Fig. 8c). Login to comment
126 In contrast, unitary current amplitude in both R104Q and K335A appeared relatively resistant to the inhibitory effects of external Pt(NO2)4 2- ions (Fig. 9a-c), again consistent with effects on macroscopic currents (Fig. 8), suggesting that positive charge at positions 104 and 335 is necessary for the full inhibitory effects of extracellular Pt(NO2)4 2- ions. Login to comment
147 b Mean fraction of control normalized current remaining in the presence of 10 mM extracellular Pt(NO2)4 2at different membrane potentials in wild type (closed circles), R104Q (closed squares), K335A (open circles), and R1128Q (open squares), quantified as the IREL in the presence of 10 mM Pt(NO2)4 2- [IREL(block)] as a fraction of that in the absence of Pt(NO2)4 2- [IREL(control)]. Login to comment
170 c Mean fractional unitary current amplitude remaining in the presence of this concentration of Pt (NO2)4 2- ions as a function of voltage, in wild type (open circles), R104Q (closed circles, left panel), and K335A (closed circles, right panel). Login to comment

PMID: 9922376 [PubMed] Dawson DC et al: "CFTR: mechanism of anion conduction."

No. Sentence Comment

562 firmed that SCN binding was reduced but not eliminated in K335D and E CFTR and showed that simply deleting D. Structural Elements That Are Important for the charge (K335A) was without effect. Login to comment

PMID: 22160394 [PubMed] Cui G et al: "Differential contribution of TM6 and TM12 to the pore of CFTR identified by three sulfonylurea-based blockers."

No. Sentence Comment

119 The major effects of increasing or decreasing sensitivity to Glyb were seen with mutations R334A, K335A, F337A, S341A, I344A, R347A, M348A, V350A, and R352A (Fig. 3 left). Login to comment
125 Mutations R334A and K335A lie in the outer vestibule of the pore of CFTR; surprisingly, the two mutations db ca 2 nA 100 ms 100 ms 2 nA Concentration (μM) 0 200 400 600 800 1000 0.2 0.4 0.6 0.8 1.0 Fractionalblock 100 ms 4 nA Fig. 2 Concentration-dependent block of WT-CFTR by Glyb, Glip and Tolb. Login to comment
133 R334A weakened block while K335A strengthened block by both blockers. Login to comment
137 On the contrary, K335A single-channel behavior is very similar to that of WT-CFTR except the single-channel conductance is slightly decreased (-0.56± 0.01 pA, n=5; see Fig. 9), as would be expected for an amino acid that affects attraction of Cl- ions. Login to comment
151 The surprising finding that mutations at six adjacent positions Q353A R352A T351A V350A A349S M348A R347A L346A V345A I344A C343A F342A S341A I340A T339A T338A F337A I336A K335A R334A WT ** ** ** ** ** ** * * * 0.8 0.6 0.4 0.2 0 Fractional block by Glyb50 μM Q353A R352A T351A V350A A349S M348A R347A L346A V345A I344A C343A F342A S341A I340A T339A T338A F337A I336A K335A R334A WT ** ** ** ** ** ** ** ** * * * * * * ** ** Fractional block by Tolb300 μM 0.8 0.6 0.4 0.2 0 Q353A R352A T351A V350A A349S M348A R347A L346A V345A I344A C343A F342A S341A I340A T339A T338A F337A I336A K335A R334A WT * ** ** ** ** ** ** ** ** Fractional block by Glip200 μM 0.8 0.6 0.4 0.2 0 Fig. 3 Alanine-scanning in TM6 to identify the amino acids that interact with the three blockers. Login to comment
162 Although mutations R334A and K335A exhibited opposite effects on steady-state block by Glyb and Glip, neither mutation altered initial block (Fig. 5). Login to comment
163 Effects on time-dependent block by mutations R334A and K335A Fractional block by Glip200 μM V1153A D1152A I1151A S1150A S1149A N1148A V1147A A1146S W1145A Q1144A L1143A T1142A S1141A M1140A I1139A N1138A M1137A A1136S L1135A T1134A WT 0 0.2 0.4 0.6 0.8 * ** ** ** ** ** ** * V1153A D1152A I1151A S1150A S1149A N1148A V1147A A1146S W1145A Q1144A L1143A T1142A S1141A M1140A I1139A N1138A M1137A A1136S L1135A T1134A WT 0 0.2 0.4 0.6 0.8 1.0 * * * * * ** ** ** ** Fractional block by Glyb50 μM Fig. 4 Alanine-scanning in TM12 to identify amino acids that interact with Glyb and Glip. Login to comment
166 Double asterisks indicate significantly different compared to WT-CFTR (p<0.01) Q353A R352A T351A V350A A349S M348A R347A L346A V345A I344A C343A F342A S341A I340A T339A T338A F337A I336A K335A R334A WT 0.3 0.2 0.1 0 * * ** ** 0.4 Initial block by 50 μM Glyb Q353A R352A T351A V350A A349S M348A R347A L346A V345A I344A C343A F342A S341A I340A T339A T338A F337A I336A K335A R334A WT 0.4 0.3 0.2 0.1 0 ** ** * Initial block by 200 μM Glip Fig. 5 Initial block of WT-CFTR and selected TM6 mutants by 50 μM Glyb (left) and 200 μM Glip (right) in symmetrical 150 mM Cl- solution. Data are shown only for those mutants which exhibited significant changes in steady-state fractional block according to Fig. 3 (bars show mean±SEM, n=5-10). Login to comment
168 Double asterisks indicate significantly different compared to WT-CFTR (p<0.01) were similar for Glyb and Glip, although the effect of R334A on Glyb was larger than for Glip and the effect of K335A was larger for Glip than Glyb (Fig. 6). Login to comment
193 Probable orientation of drugs in the pore Glyb and Glip are identical molecules along most of their lengths, differing only in the substituents on the ring at the Q353A R352A T351A V350A A349S M348A R347A L346A V345A I344A C343A F342A S341A I340A T339A T338A F337A I336A K335A R334A WT 0.8 0.6 0.2 0 ** ** ** ** Time-dependent block by 50 μμM Glyb Q353A R352A T351A V350A A349S M348A R347A L346A V345A I344A C343A F342A S341A I340A T339A T338A F337A I336A K335A R334A WT ** ** * ** * Time-dependent block by 200 μM Glip 0.4 0.8 0.6 0.2 00.4 Fig. 6 Time-dependent block of WT-CFTR and selected TM6 mutants by 50 μM Glyb (left) and 200 μM Glip (right) in symmetrical 150 mM Cl- solution. Data are shown only for those mutants which exhibited significant changes in fractional block according to Fig. 3 (bars show mean±SEM, n=5-10). Login to comment
221 The effects of mutations R334A and K335A are indirect, likely related to the movement of chloride within the pore, or the stabilization of the outer vestibule. Login to comment
239 Hence, strong time-dependent block of macropatch currents, and the appearance of multiple drug-induced closed states in single-channel recordings, may not arise from 0.4 pA 2 s M348A c f 0.2 pA 2 s F337A c f 0.4 pA 2 s K335A c f 0.4 pA 2 s c s2 f D1152A 0.4 pA 2 s T1134A c f 0.4 pA 2 s S1141A c f s2 0.4 pA 2 s c f WT 2000 4000 #ofevents 0.0 -0.5 -1.0 Current (pA) -1.50.5 3000 9000 #ofevents 0.0 -0.5 -1.0 Current (pA) -1.50.5 6000 400 1200 #ofevents 0.0 -0.5 -1.0 Current (pA) -1.50.5 800 1600 1000 3000 #ofevents 0.0 -0.5 -1.0 Current (pA) -1.50.5 2000 500 #ofevents 0.0 -0.5 -1.0 Current (pA) -1.50.5 1000 4000 12000 #ofevents 0.0 -0.5 -1.0 Current (pA) -1.50.5 8000 200 600 #ofevents 0.0 -0.5 -1.0 Current (pA) -1.50.5 400 Fig. 9 Representative single-channel traces for WT-, K335A-, F337A-, M348A-, T1134A-, S1141A-, and D1152A-CFTR (left) from excised inside-out membrane patches with symmetrical 150 mM Cl- solution, and their all-points amplitude histograms (right). Login to comment

PMID: 9512029 [PubMed] Mansoura MK et al: "Cystic fibrosis transmembrane conductance regulator (CFTR) anion binding as a probe of the pore."

No. Sentence Comment

62 Expression levels Wild-type and 11 mutant CFTR constructs were used in this study: G91A, G91E, G91R, G314A, G314D, G314E, G314Q, K335R, K335A, K335D, and K335E. Login to comment
107 Neither the arginine (K335R) nor the alanine substitution (K335A) resulted in any substantial change in the permeability ratios (with the exception of SCN for K335A). Login to comment
112 The conductance ratios for anions judged by shifts in reversal potential to be most highly permeant (SCN, NO3, and Br) were all increased significantly by substituting a negatively charged residue (D or E) for K335, whereas mutants in which the charge was conserved (K335R) or removed (K335A) were identical to wtCFTR. Login to comment
113 The K335D and K335E constructs also exhibited increased conductance ratios for I, a result previously reported by Anderson et al. (1991) for K335E CFTR. Login to comment
137 Permeability Ratios Wild type 4-9 3.42 Ϯ 0.28 1.42 Ϯ 0.04 1.22 Ϯ 0.02 0.39 Ϯ 0.01 0.44 Ϯ 0.03 G91A 3-6 3.24 Ϯ 0.26 1.53 Ϯ 0.04 1.27 Ϯ 0.02 0.37 Ϯ 0.04 0.40 Ϯ 0.04 G91E 3-7 3.50 Ϯ 0.54 1.59 Ϯ 0.04 1.27 Ϯ 0.01 0.35 Ϯ 0.01 0.51 Ϯ 0.04 G91R 3-4 5.26 ؎ 0.46* 1.60 Ϯ 0.03 1.40 ؎ 0.01* 0.32 Ϯ 0.04 0.64 ؎ 0.04* G314A 3-4 2.87 Ϯ 0.17 1.45 Ϯ 0.03 1.19 Ϯ 0.02 0.31 Ϯ 0.03 0.33 Ϯ 0.03 G314D 4 3.42 Ϯ 0.34 1.44 Ϯ 0.05 1.25 Ϯ 0.04 0.33 Ϯ 0.03 0.51 Ϯ 0.05 G314E 3-4 3.72 Ϯ 0.56 1.65 ؎ 0.09* 1.35 ؎ 0.03* 0.49 Ϯ 0.04 0.53 Ϯ 0.04 G314Q 3-4 3.89 Ϯ 0.37 1.62 Ϯ 0.11 1.27 Ϯ 0.04 0.36 Ϯ 0.03 0.62 Ϯ 0.05 K335R 3-5 3.44 Ϯ 0.29 1.35 Ϯ 0.04 1.22 Ϯ 0.03 0.40 Ϯ 0.05 0.41 Ϯ 0.07 K335A 5-6 5.34 ؎ 0.58* 1.48 Ϯ 0.06 1.28 Ϯ 0.04 0.37 Ϯ 0.03 0.60 Ϯ 0.06 K335D 4-6 3.02 Ϯ 0.19 1.50 Ϯ 0.03 1.10 ؎ 0.02* 0.54 ؎ 0.04* 0.65 ؎ 0.06* K335E 5-8 3.64 Ϯ 0.21 1.48 Ϯ 0.06 1.29 Ϯ 0.03 0.46 Ϯ 0.04 1.10 ؎ 0.04* B. Conductance Ratios Wild type 4-9 0.14 Ϯ 0.02 0.75 Ϯ 0.02 0.64 Ϯ 0.02 0.52 Ϯ 0.03 0.18 Ϯ 0.03 G91A 3-6 0.14 Ϯ 0.01 0.77 Ϯ 0.02 0.61 Ϯ 0.02 0.47 Ϯ 0.02 0.19 Ϯ 0.02 G91E 3-7 0.15 Ϯ 0.03 0.73 Ϯ 0.02 0.60 Ϯ 0.01 0.50 Ϯ 0.04 0.30 Ϯ 0.02 G91R 3-4 0.14 Ϯ 0.00 0.84 Ϯ 0.01 0.63 Ϯ 0.01 0.32 ؎ 0.01* 0.14 Ϯ 0.01 G314A 3-4 0.30 Ϯ 0.09 0.89 ؎ 0.01* 0.66 Ϯ 0.01 0.48 Ϯ 0.09 0.24 Ϯ 0.01 G314D 4 0.28 Ϯ 0.05 0.82 Ϯ 0.01 0.70 Ϯ 0.02 0.49 Ϯ 0.06 0.27 Ϯ 0.03 G314E 3-4 0.62 ؎ 0.07* 1.18 ؎ 0.04* 0.84 ؎ 0.05* 0.42 Ϯ 0.05 0.29 Ϯ 0.09 G314Q 3-4 0.63 ؎ 0.02* 1.01 ؎ 0.04* 0.82 ؎ 0.03* 0.50 Ϯ 0.02 0.42 ؎ 0.02* K335R 3-5 0.14 Ϯ 0.01 0.76 Ϯ 0.03 0.61 Ϯ 0.02 0.59 Ϯ 0.06 0.16 Ϯ 0.03 K335A 6 0.20 Ϯ 0.03 0.77 Ϯ 0.02 0.61 Ϯ 0.02 0.45 Ϯ 0.03 0.21 Ϯ 0.02 K335D 4-6 0.65 ؎ 0.04* 1.25 ؎ 0.02* 0.89 ؎ 0.02* 0.61 Ϯ 0.06 0.58 ؎ 0.06* K335E 5-8 0.50 ؎ 0.06* 1.19 ؎ 0.03* 0.89 ؎ 0.02* 0.53 Ϯ 0.03 0.48 ؎ 0.03* (A) The apparent permeability ratios (PS/PCl) for each substitute anion were calculated from the shift in reversal potential using the Goldman-Hodgkin-Katz relation (noted in Materials and Methods). Login to comment
144 Similar negative results were obtained for the K335R and K335A constructs, but in the K335D and K335E mutants maximal attenuation by [SCN]o was reduced by nearly 50%, although the apparent binding affinity was unaffected. Login to comment
145 The result is consistent with the notion that the affinity of anion binding was not diminished in the K335D and K335E constructs, but the impact of binding on conduction was reduced. Login to comment
166 Similarly, neither the alanine (K335A) nor the arginine (K335R) substituted K335 constructs exhibited an alteration in sensitivity to activating conditions. Login to comment
169 TABLE 4 Quantitative analyses of the macroscopic I-V shape changes Mutant ⌬ Net charge n RR g(ϩ30)/g(-30) RR/RRWT Wild type 5 1.220 Ϯ 0.06 1.00 G91A 0 4 1.293 Ϯ 0.06 1.06 G91E -1 5 1.512 ؎ 0.10* 1.24 G91R 1 4 8.041 ؎ 0.87* 6.59 G314A 0 4 1.201 Ϯ 0.09 0.98 G314D -1 4 1.362 Ϯ 0.08 1.12 G314E -1 7 1.405 Ϯ 0.08 1.15 G314Q 0 5 1.376 Ϯ 0.10 1.13 K335R 0 4 1.209 Ϯ 0.06 0.99 K335A -1 4 1.295 Ϯ; 0.07 1.06 K335D -2 5 0.762 ؎ 0.02* 0.62 K335E -2 4 0.919 ؎ 0.02* 0.75 The slope conductance was measured at ϩ30 mV and -30 mV with respect to the reversal potential. Login to comment
173 TABLE 5 Concentration-dependent activation of wtCFTR, G91, G314, and K335 variants by IBMX in the presence of 10 ␮M forskolin Mutant n K1/2(IBMX) (mM) Wild type 15 0.35 Ϯ 0.04 G91A 5 0.42 Ϯ 0.06 G91E 8 0.51 ؎ 0.06* G91R 5 0.49 Ϯ 0.09 G314A 10 1.21 ؎ 0.11* G314D 3 1.35 ؎ 0.16* G314E 8 6.39 ؎ 1.35* G314Q 4 14.26 ؎ 6.64* K335R 4 0.46 Ϯ 0.04 K335A 2 0.35 Ϯ 0.15 K335D 7 0.87 ؎ 0.13* K335E 3 0.95 ؎ 0.07* The steady-state slope conductance was measured at -60 mV as increasing concentrations of IBMX (0.02-5.0 mM) were added to the perfusate in the continued presence of 10 mM forskolin. Login to comment
198 The results presented here are consistent with the notion that the binding of anions within the CFTR pore is a sensitive indicator of changes in pore structure whereas permeability ratios appear to be rather insensitive to similar TABLE 6 Qualitative summary of the functional consequences of mutations at G91, G314, and K335 Property G91 (TM1) K335 (TM6) G314 (TM5) G91A G91E G91R K335R K335A K335D K335E G314A G314D G314E G314Q I-V shape - - ϩϩϩ - - ϩϩ ϩ - - - - Psub/PCl - - - - - - ϩϩ - - - - gsub/gCl - - - - - ϩϩϩ ϩϩϩ ϩϩ - ϩϩϩ ϩϩϩ SCN- binding - - - - - ϩϩϩ ϩϩϩ ϩϩ - ϩϩϩϩ ϩϩϩϩ Activation - - - - - ϩϩ ϩϩ ϩϩϩ ϩϩϩ ϩϩϩϩ ϩϩϩϩ Results are expressed as follows: -, function of the CFTR construct with the indicated substitution was indistinguishable from wild type; ϩ to ϩϩϩϩ, semiquantitative indication of the magnitude of the change in the function compared with wild type. Login to comment
108 Neither the arginine (K335R) nor the alanine substitution (K335A) resulted in any substantial change in the permeability ratios (with the exception of SCN for K335A). Login to comment
138 Permeability Ratios Wild type 4-9 3.42 afe; 0.28 1.42 afe; 0.04 1.22 afe; 0.02 0.39 afe; 0.01 0.44 afe; 0.03 G91A 3-6 3.24 afe; 0.26 1.53 afe; 0.04 1.27 afe; 0.02 0.37 afe; 0.04 0.40 afe; 0.04 G91E 3-7 3.50 afe; 0.54 1.59 afe; 0.04 1.27 afe; 0.01 0.35 afe; 0.01 0.51 afe; 0.04 G91R 3-4 5.26 d1e; 0.46* 1.60 afe; 0.03 1.40 d1e; 0.01* 0.32 afe; 0.04 0.64 d1e; 0.04* G314A 3-4 2.87 afe; 0.17 1.45 afe; 0.03 1.19 afe; 0.02 0.31 afe; 0.03 0.33 afe; 0.03 G314D 4 3.42 afe; 0.34 1.44 afe; 0.05 1.25 afe; 0.04 0.33 afe; 0.03 0.51 afe; 0.05 G314E 3-4 3.72 afe; 0.56 1.65 d1e; 0.09* 1.35 d1e; 0.03* 0.49 afe; 0.04 0.53 afe; 0.04 G314Q 3-4 3.89 afe; 0.37 1.62 afe; 0.11 1.27 afe; 0.04 0.36 afe; 0.03 0.62 afe; 0.05 K335R 3-5 3.44 afe; 0.29 1.35 afe; 0.04 1.22 afe; 0.03 0.40 afe; 0.05 0.41 afe; 0.07 K335A 5-6 5.34 d1e; 0.58* 1.48 afe; 0.06 1.28 afe; 0.04 0.37 afe; 0.03 0.60 afe; 0.06 K335D 4-6 3.02 afe; 0.19 1.50 afe; 0.03 1.10 d1e; 0.02* 0.54 d1e; 0.04* 0.65 d1e; 0.06* K335E 5-8 3.64 afe; 0.21 1.48 afe; 0.06 1.29 afe; 0.03 0.46 afe; 0.04 1.10 d1e; 0.04* B. Conductance Ratios Wild type 4-9 0.14 afe; 0.02 0.75 afe; 0.02 0.64 afe; 0.02 0.52 afe; 0.03 0.18 afe; 0.03 G91A 3-6 0.14 afe; 0.01 0.77 afe; 0.02 0.61 afe; 0.02 0.47 afe; 0.02 0.19 afe; 0.02 G91E 3-7 0.15 afe; 0.03 0.73 afe; 0.02 0.60 afe; 0.01 0.50 afe; 0.04 0.30 afe; 0.02 G91R 3-4 0.14 afe; 0.00 0.84 afe; 0.01 0.63 afe; 0.01 0.32 d1e; 0.01* 0.14 afe; 0.01 G314A 3-4 0.30 afe; 0.09 0.89 d1e; 0.01* 0.66 afe; 0.01 0.48 afe; 0.09 0.24 afe; 0.01 G314D 4 0.28 afe; 0.05 0.82 afe; 0.01 0.70 afe; 0.02 0.49 afe; 0.06 0.27 afe; 0.03 G314E 3-4 0.62 d1e; 0.07* 1.18 d1e; 0.04* 0.84 d1e; 0.05* 0.42 afe; 0.05 0.29 afe; 0.09 G314Q 3-4 0.63 d1e; 0.02* 1.01 d1e; 0.04* 0.82 d1e; 0.03* 0.50 afe; 0.02 0.42 d1e; 0.02* K335R 3-5 0.14 afe; 0.01 0.76 afe; 0.03 0.61 afe; 0.02 0.59 afe; 0.06 0.16 afe; 0.03 K335A 6 0.20 afe; 0.03 0.77 afe; 0.02 0.61 afe; 0.02 0.45 afe; 0.03 0.21 afe; 0.02 K335D 4-6 0.65 d1e; 0.04* 1.25 d1e; 0.02* 0.89 d1e; 0.02* 0.61 afe; 0.06 0.58 d1e; 0.06* K335E 5-8 0.50 d1e; 0.06* 1.19 d1e; 0.03* 0.89 d1e; 0.02* 0.53 afe; 0.03 0.48 d1e; 0.03* (A) The apparent permeability ratios (PS/PCl) for each substitute anion were calculated from the shift in reversal potential using the Goldman-Hodgkin-Katz relation (noted in Materials and Methods). Login to comment

PMID: 19448737 [PubMed] Zhou JJ et al: "Evidence that extracellular anions interact with a site outside the CFTR chloride channel pore to modify channel properties."

No. Sentence Comment

67 Similar weakening of block by internal Pt(NO2)4 2-was also observed in K114C, K329A, K335A, and R1128Q (Fig. 2), as well as R334Q (Zhou et al. 2007). Login to comment
80 Nevertheless, the apparent Cl- dependence of block was significantly reduced in both K335A and R899Q, and significantly enhanced in R117Q (Fig. 4D). Login to comment
127 The effects of external Pt(NO2)4 2are sensitive to mutations away from the pore (K892Q, R899Q) but not deep within the pore (K335A, R334Q), which would be expected to alter ion-ion interactions in the pore. Login to comment
145 Interactions between external Cl- and internal Pt(NO2)4 2are also weakened in K335A (Fig. 4D), probably as a result of a decrease in direct pore-mediated interactions in this low-conductance mutant. Login to comment

PMID: 23709221 [PubMed] Cui G et al: "Two salt bridges differentially contribute to the maintenance of cystic fibrosis transmembrane conductance regulator (CFTR) channel function."

No. Sentence Comment

213 We conclude that the subconductance states in CFTR probably also represent pore conformational change for the following reasons: 1) the CFTR channel pore forms from one polypeptide as a monomer and only bears one permeation pathway (12); 2) the s1 and s2 states occur as rare events in some point mutations, such as T338A/Cand K335A/C-CFTR, which do not appear to affect gross pore architecture, whereas they are frequent events in CFTR channels bearing salt bridge mutations, such as R352A- and R347A-CFTR, as discussed above; 3) mutations at sites involved in salt bridges (such as Arg347 , Arg352 , Asp924 , and Asp993 ) result in much more frequent occupancy of subconductance states; 4) mutations at sites involved in salt bridges (such as Arg347 and Arg352 ) lead to greatly altered sensitivity to pore blockers (7, 13); and 5) the subconductance behavior is not affected by different concentrations of Clafa; or by changes in membrane potential (12, 16). Login to comment

PMID: 25277268 [PubMed] Broadbent SD et al: "The cystic fibrosis transmembrane conductance regulator is an extracellular chloride sensor."

No. Sentence Comment

112 To explore the role of phosphorylation further, we studied the effect of deleting the R domain from CFTR (residues 634-836) [12, 7], which removes all the major PKA/PKC Table 1 Summary of the FSK stimulation of whole cell currents and Erev shifts observed with the CFTR constructs used in this study CFTR Construct n FSK Stimulation (%&#b1;SEM) Erev shift (mV&#b1;SEM) WT (50 bc;M ATP) 5 180&#b1;96 15.0&#b1;3.6 WT (100 bc;M ATP) 6 12,000&#b1;6,000 15.2&#b1;3.0 WT (300 bc;M ATP) 8 1,200&#b1;600 17.0&#b1;3.0 WT (1 mM ATP) 24 13,000&#b1;6,000 23.7&#b1;1.8 WT (1.3 mM ATP) 9 1,400&#b1;900 16.7&#b1;2.6 WT (2 mM ATP) 24 6,100&#b1;5,300 16.7&#b1;1.6 WT (5 mM ATP) 7 1,600&#b1;1,000 20.1&#b1;4.4 WT (50 bc;M ATP + 50 bc;M P-ATP) 7 224&#b1;130 15.3&#b1;1.0 WT + Genistein 4 7,600&#b1;5,200 26.1&#b1;5.4 WT + AMP-PNP 5 2,800&#b1;2,500 21.8&#b1;5.5 WT (3 mM MgCl2) 7 28,000&#b1;17,000 18.3&#b1;3.1 R104Q 5 4,600&#b1;1,600 28.6&#b1;4.7 K114C 5 12,000&#b1;6,700 29.2&#b1;3.0 R117Q 4 33,000&#b1;20,000 30.1&#b1;3.4 K329A 5 13,000&#b1;10,000 33.7&#b1;2.1 R334Q 9 13,000&#b1;6,700 27.3&#b1;2.9 K335A 5 3,200&#b1;1,500 20.8&#b1;7.1 W401G 7 2,600&#b1;1,800 18.5&#b1;4.8 Delta-R (No Stim) 5 - 25.1&#b1;2.7 Delta-R (No FSK, Genistein) 5 140&#b1;13 22.7&#b1;3.0 Delta-R (FSK, No Genistein) 4 89&#b1;14 15.6&#b1;6.0 Delta-R (FSK + Genistein) 6 639&#b1;432 25.1&#b1;4.9 Delta-R-E1371S (No FSK) 9 - 21.4&#b1;4.8 Delta-R-E1371S (FSK) 4 2,600&#b1;1,400 15.3&#b1;4.7 K892Q 7 16,000&#b1;9,500 36.8&#b1;4.8 R899E 4 1,200&#b1;400 25.0&#b1;2.7 R899K 4 1,600&#b1;900 26.6&#b1;2.9 R899Q 7 5,400&#b1;2,800 30.0&#b1;1.3 R899Q + AMP-PNP 4 72,000&#b1;50,000 15.2&#b1;2.8 R899Q-E1371Q (No FSK) 4 - 18.4&#b1;5.9 R899Q-E1371Q (FSK) 6 107&#b1;48 15.6&#b1;3.0 R1128Q 6 14,000&#b1;6,100 41.1&#b1;4.2 Y1219G 6 3,200&#b1;2,500 19.2&#b1;3.3 E1371Q (No FSK) 6 - 25.5&#b1;3.5 E1371Q (FSK) 8 -28&#b1;9 22.3&#b1;4.0 E1371Q (FSK, No ATP, No GTP) 8 270&#b1;130 19.4&#b1;4.5 E1371Q + AMP-PNP (No FSK) 4 - 24.7&#b1;6.5 E1371Q + AMP-PNP (FSK) 8 180&#b1;170 17.4&#b1;4.0 Vector Control 4 15&#b1;38 - FSK stimulation was calculated as the percentage increase in current density at -60 mV from the Erev, after 5-min exposure to 10 bc;M FSK. Login to comment
162 In support of this conclusion, the stimulating effect of [Cl- ]o cannot be due to the ion entering the pore, since mutations that do affect CFTR Cl-conductance (R104Q, R117Q, R334Q, K335A) have no effect on [Cl- ]o stimulation (Fig. 2), and the one site that is important for sensing (R899) does not affect Cl-conductance [45, 47]. Login to comment