ABCMdb

ABCC7 p.Arg334His

None has been submitted yet.

Publications

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

No. Sentence Comment

318 pH Titration of R334H CFTR Altered Conductance and the Shape of the I-V Relation It was of interest to compare the response to changes in bath pH of R334C CFTR with that of R334H CFTR. Login to comment
320 An I-V plot from a representative experiment in which the pH of the solution bathing an oocyte expressing R334H CFTR was acidified from 7.4 to 6.02 and then 4.80 is shown in Fig. 15 A. Login to comment
324 Stepwise acidification of the bath led to stepwise increases in the conductance of oocytes expressing R334C or R334H CFTR and corresponding, stepwise increases in the rectification ratio, whereas similar pH changes resulted in only modest changes in the conductance of oocytes expressing wt CFTR. Login to comment
327 The observed changes seen with wt CFTR were opposite of those seen with oocytes expressing R334C or R334H CFTR, suggesting that the pH induced changes due to protonation of R334C or R334H were, if anything, slightly underestimated. Login to comment
328 The distinct pKa`s of the R334C and R334H variants favor the notion that these pH-dependent effects are due to titration of the side chain at position 334, as opposed to a mutation-induced exposure of a titratable site at another locus (Coulter et al., 1995). Login to 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
344 The Effects of Charge Deposition at Position 334 Were Consistent with the Predictions of Charged-vestibule Models for the Anion Conduction Path The results of covalent modification and pH titration of R334C and R334H CFTR, as well as the functional impact of amino acid substitutions at this site, pointed to an important role for the charge at position 334 in determining the conduction properties of CFTR. Login to comment
350 pH titration of oocytes expressing R334H CFTR altered both the conductance and the shape of the I-V relation. Login to comment
351 (A) I-V plots from an oocyte expressing R334H CFTR. Login to comment
397 Titration of R334C and R334H CFTR by varying bath pH was also well described by a continuum model in which the changes in conductance and I-V shape were largely attributed to changes in ⌿o (unpublished data). Login to comment
417 Fig. 18 A summarizes the data from experiments in which charge changes were effected in R334C and R334H CFTR by means of chemical modification or pH titration. Login to comment
420 Data points include charge changes brought about by thiol modification of R334C CFTR with positively charged reagents (open triangles), and negatively charged reagents (closed triangles), pH titration of R334C CFTR (closed circles), and pH titration of R334H CFTR (open circles). Login to comment
423 Thiol modification of R334C CFTR with positively charged reagents (open triangles) was treated as adding a single positive charge; thiol modification of R334C with negatively charged reagents (closed triangles) was treated as adding a single negative charge; pH titration of R334H CFTR (open circles) was treated as adding a time-average positive charge determined by the bath pH, assuming a pKa of 5.68; and pH titration of R334C CFTR (closed circles) was treated as adding a time-average negative charge determined by the bath pH assuming a pKa of 8.17. 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

11 Fixed positive charge at this site appears to play a role in Au(CN)2 _ binding, as judged by multiple substitutions of differently charged amino acid side chains and also by the pH dependence of block conferred by the R334H mutant. Login to comment
53 Block of wild-type, R334C-, R334E-, R334H-, R334K-, R334L- and R334Q-CFTR by 100 mM and 1 mM intracellular Au(CN)2 _ are compared in Fig. 4B. Login to comment
79 Adirectinvestigationoftheroleofpositivecharge A previous mutagenic investigation of arginine 334 emphasized the role played by the fixed positive charge at this position, and elegantly demonstrated this effect by titrating the side chain charge in R334H by changing the external pH (Smith et al. 2001). Login to comment
80 Although we have studied mutants with neutral, positively charged and negatively charged side chains, the pH dependence of R334H provides a unique opportunity to examine the effect of side chain charge independently of side chain shape. Login to comment
81 We therefore examined the effect of changing extracellular pH on Au(CN)2 _ block of wild-type and R334H-CFTR. Login to comment
82 As shown in Fig. 7, Au(CN)2 _ blocked R334H more strongly at pH 5.5 than at pH 9.0, whereas block of wild-type was X. Gong and P. Linsdell392 J Physiol549.2 Figure 5. Login to comment
88 However, the effect of changing the extracellular anion on the apparent affinity of Au(CN)2 _ block was not strongly pH dependent in R334H (Fig. 8), and at all pHs studied the effect of changing from extracellular gluconate to Cl_ , or from Cl_ to SCN_ , was small (as judged by the Kd(0) ratio) compared to the effect seen in wild-type at pH 7.4. Login to comment
89 These experiments on R334H at different pHs strongly suggest that Au(CN)2 _ blocking affinity and the interaction between intracellular Au(CN)2 _ ions and extracellular anions show different dependencies on side chain charge at position 334. Login to comment
94 Consistent with this notion, and again as noted by Smith et al. (2001), rectification was pH dependent in R334H but not in wild-type (Fig. 9A). Login to comment
101 Extracellular pH modifies Au(CN)2 _ block of R334H- but not wild-type CFTR A, example I-V relationships for wild-type and R334H at extracellular pHs of 5.5 and 9.0, before (control) and after (+Au(CN)2) addition of 100 mM Au(CN)2 _ to the intracellular solution. Login to comment
103 Mean of data from 3-5 patches, fitted as in Fig. 1B. C, effect of extracellular pH on Kd(0) in wild-type (0) and R334H (1). Login to comment
112 Extracellular pH does not affect extracellular anion dependence of Au(CN)2 _ block in R334H-CFTR The effect of changing the extracellular anion (from Cl_ to gluconate or from Cl_ to SCN_ ), quantified by the Kd(0) ratio as in Fig. 3D, appears independent of pH in R334 and is significantly reduced relative to wild-type at pH 7.4. Login to comment
116 Furthermore, this rectification acquires pH dependence in R334H not seen in wild-type. Login to comment
143 In R334H, positive charge does appear to enhance Au(CN)2 _ binding, since low pH, which is expected to favour protonation of this side chain (see also Smith et al. 2001), increases the apparent affinity of block (Fig. 7). Login to comment
147 These different effects of side chain charge are clearly demonstrated in R334H, which shows pH-dependent rectification (Fig. 9A) and Au(CN)2 _ affinity (Fig. 7) but pH-independent interactions between intracellular Au(CN)2 _ and extracellular anions (Fig. 8). Login to comment
148 The fact that tight Au(CN)2 _ binding and strong Au(CN)2 _ -anion interactions are separable by mutagenesis is also evident in R334H and R334L (Fig. 5). Login to comment

PMID: 14598388 [PubMed] Liu X et al: "CFTR: what's it like inside the pore?"

No. Sentence Comment

96 Summarized in Figure 4 are charge-induced changes in R334C or R334H CFTR conductance that result from alteration of external pH or exposure of oocytes expressing R334C CFTR to charged methanethiosulfonate (MTS) reagents. Login to comment
98 Acidification of the bath solution of oocytes expressing R334C or R334H CFTR, or modification of R334C CFTR by a positively charged MTS Fig. 4. Login to comment
104 (C) pH titration of R334H. Login to comment
108 On the other hand, alkalinization of the bath solution of oocytes expressing R334C or R334H CFTR or modification of R334C CFTR by a negatively charged MTS reagent, MTSES (sodium [2-sulfonatoethyl]methanethiosulfonate), decreased the whole cell conductance and enhanced the inward rectification of the shape of the I-V plots. Login to comment

PMID: 17673962 [PubMed] Zhou JJ et al: "Direct and indirect effects of mutations at the outer mouth of the cystic fibrosis transmembrane conductance regulator chloride channel pore."

No. Sentence Comment

85 Figure 3 shows the blocking effects of internally applied Pt(NO2)4 2À in six different channel mutants (R334C, R334E, R334H, R334K, R334L, R334Q) under conditions of both low (Fig. 3a) and high (Fig. 3b) extracellular ClÀ concentration. Login to comment
91 With elevated extracellular ClÀ , the Kd(0) was significantly increased only in R334C and R334E; not significantly altered in R334K, R334L and R334Q; and significantly decreased in R334H (Fig. 5b). Login to comment
93 These R334 mutations also exhibited a weakened sensitivity of blocker voltage dependence (quantified as -zd, Fig. 5) to external ClÀ concentration (Fig. 5c), although because of the small magnitude of this effect only R334C, R334H and R334Q reached a level of statistical significance (Fig. 5c). Login to comment
106 Comparison of the mean Kd estimated for suramin (at 0 mV) shows that R334C, R334E, R334K, R334L and R334Q were all associated with weakened suramin block, with only R334H failing to significantly affect suramin block (Fig. 7). Login to comment
129 Mean of data from three to eight patches. Fitted lines are to equation 1 as described in Figure 1 for wild type and R334Q and with the following parameters for other channel variants: R334C 4 mM external ClÀ , Kd(0) = 1362 lM, zd = À0.295; R334C 154 mM external ClÀ , Kd(0) = 836 lM, zd = À0.219; R334E 4 mM external ClÀ , Kd(0) = 759 lM, zd = À0.376; R334E 154 mM external ClÀ , Kd(0) = 564 lM, zd = À0.173; R334H 4 mM external ClÀ , Kd(0) = 140 lM, zd = À0.166; R334H 154 mM external ClÀ , Kd(0) = 119 lM, zd = À0.149; R334K 4 mM external ClÀ , Kd(0) = 143 lM, zd = À0.314; R334K 154 mM external ClÀ , Kd(0) = 317 lM, zd = À0.374; R334L 4 mM external ClÀ , Kd(0) = 176 lM, zd = À0.258; R334L 154 mM external ClÀ , Kd(0) = 284 lM, zd = À0.366 extracellular Pt(NO2)4 2À by normalizing current amplitude at the hyperpolarized extreme of the voltage range studied, -80 mV (Fig. 10b). Login to comment
159 These plots represent mean data from four to seven patches. Fitted lines are to equation 1 with the following parameters: wild type, Kd(0) = 2.51 lM, zd = À0.042; R334C, Kd(0) = 18.5 lM, zd = À0.056; R334E, Kd(0) = 25.0 lM, zd = À0.107; R334H, Kd(0) = 3.10 lM, zd = À0.085; R334K, Kd(0) = 6.31 lM, zd = À0.232; R334L, Kd(0) = 4.08 lM, zd = À0.061; R334Q, Kd(0) = 6.64 lM, zd = À0.239 with our previous suggestion that intracellular Au(CN)2 À blocks the channel by interacting directly with R334, several reasons prompt us to suggest that Pt(NO2)4 2À does not interact directly with the arginine side chain at this position. Login to comment
228 ), R334E (5), R334H (j), R334K (), R334L (h), R334Q (u); c wild type (d), K95Q (m), R303Q (Å). 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

229 Hipper et al. (1995) reported that the mutations R334E, R334H, K335E, K335H, R347E, and R347H did not alter CFTR conduction properties, but careful inspection of the data presented revealed that the level of CFTR expression was very low so that altered properties of mutant CFTRs might have been easily obscured. Login to comment

PMID: 7589561 [PubMed] Hipper A et al: "Mutations in the putative pore-forming domain of CFTR do not change anion selectivity of the cAMP activated Cl- conductance."

No. Sentence Comment

6 The following mutations were examined: K335E, R347E, R334E, K335H, R347H, R334H. Login to comment
9 Various mutants for which positively charged amino acids were replaced by histidines (K335H, R347H, R334H) did not show pH sensitivity of the IBMX activated wc conductance. Login to comment
32 Synthesis of mutated CFTR-cDNA was induced by annealing of ampicillin repair oligonucleotide and oligonucleotide primers carrying the respective mutation changing positively charged to negatively charged amino acids (R334E, R347E, K335E) or replacing R and K at these positions by histidines (R334H, R347H, K335H). Login to comment
80 Next, positively charged amino acids R334, R347, K335 located in the putative 6th pore forming transmembrane a-helical domain of CFTR, were exchanged by histidines (R334H, R347H, K335H) or by the negatively charged glutamate (R334E, R347E, K335E). Login to comment
81 Wc conductances were activated significantly by IBMX in all 6 mutants but to variable degrees (AG in/.tS): 3.2 + 0.6 (R334E, n = 20), 2.7 + 0.6 (R334H, n = 13), 7.1 + 0.9 (K335E, n-- 20), 2.8 + 0.7 (K335H, n = 10), 3.2 + 0.04 (R347E, n = 32) and 1.8 + 0.3 (R347H, n = 10). Login to comment
91 Following previous experiments [7] wc C1- conductances were examined in mutants bearing a histidine mutation (K335H, R347H, R334H) at different extracellular pH values. Login to comment
94 aL IFEBS Letters 374 (1995) 312-316 - ~ - K335H (n=7) .... ~ .... R347H (n=8) 8 - • R334H (n=5) ...6- I~ ...L 25.5/6 7.5 8/8.5 opH Fig. 5. Summary of the conductances obtained from IBMX stimulated oocytes at different extracellular pH values. Login to comment
95 Experiments were performed with oocytes overexpressing three different CFTR mutants: K335H, R347H, R334H. Login to comment
108 In the present study we repeated some of the published (K335E, R347E, R347H) and performed additional mutations (R334E, R334H, K335H) which are all located in the putative sixth transmembrane domain and overexpressed the respective CFTRs in oocytes. Login to comment
117 Additional mutations were constructed in which positively charged lysine and two arginines in the sixth transmembrane domain were replaced by pH-sensitive histidines (R334H, K335H, R347H). Login to comment

PMID: 15130785 [PubMed] Gong X et al: "Maximization of the rate of chloride conduction in the CFTR channel pore by ion-ion interactions."

No. Sentence Comment

35 Results and discussion Previously we characterized the properties of six different R334 mutants (R334C, R334E, R334H, R334K, R334L, and R334Q) [19]. Login to comment
50 Comparison of unitary current amplitude at )100 mV showed that, compared to wild type, mean current was reduced by between 53 (in R334K) and 91% (in R334H) (Fig. 2B). Login to comment
65 (A) Unitary current-voltage relationships for each of the channel variants shown in Fig. 1: (d) wild type, (r) R334C, (j) R334E, (}) R334H, (s) R334K, () R334L, (.) Login to comment