ABCC7 p.Arg352His
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PMID: 10220340
[PubMed]
Guinamard R et al: "Arg352 is a major determinant of charge selectivity in the cystic fibrosis transmembrane conductance regulator chloride channel."
No.
Sentence
Comment
101
In cell-attached patches, with 140 mM NaCl in the pipet, the single-channel conductances (in picosiemens) were 6.0 ( 0.3 for the wild type (n ) 7), 5.3 ( 0.3 for R352C (n ) 11), 4.2 ( 0.1 for R352Q (n ) 10), 4.0 ( 0.2 for R352H (n ) 4), and 5.7 ( 0.2 for Q353C (n ) 8).
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ABCC7 p.Arg352His 10220340:101:222
status: NEW114 For the R352H mutant, the single-channel conductance was sensitive to the pH of the bath solution; the single-channel conductance at pH 7.2 was 3.7 ( 0.1 pS (n ) 6), and at pH 5.4, it was 4.3 ( 0.1 pS (n ) 5) (Figure 4).
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ABCC7 p.Arg352His 10220340:114:8
status: NEW131 (B) Average single-channel current-voltage relationships for the wild type (O) and the R352C (0), R352Q (3), and R352H (bath pH of 7.2) (]) mutants.
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ABCC7 p.Arg352His 10220340:131:113
status: NEW133 The symbols for R352Q and R352H overlap at several voltages.
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ABCC7 p.Arg352His 10220340:133:26
status: NEW136 (C and D) Single-channel recordings from inside-out patches obtained from cells expressing either (C) wild-type CFTR or (D) the R352H mutant (bath pH of 7.2).
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ABCC7 p.Arg352His 10220340:136:128
status: NEW149 FIGURE 4: Reversal potential of the R352H mutant which is shifted by the protonation state of the histidine.
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ABCC7 p.Arg352His 10220340:149:36
status: NEW150 Single-channel recordings for R352H at various applied voltages in a 10-fold NaCl gradient as described in Figure 3A except the bath pH was 5.4 (A) and 7.2 (B).
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ABCC7 p.Arg352His 10220340:150:30
status: NEW151 (C) Single-channel current-voltage relationships for R352H with the bath pH at pH 5.4 (O) and pH 7.2 (4).
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ABCC7 p.Arg352His 10220340:151:53
status: NEW158 To determine the role of the positive charge at position 352, we substituted histidine for Arg352.
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ABCC7 p.Arg352His 10220340:158:77
status: NEW160 Maintaining the positive charge at position 352 with the R352H mutation and a bath pH of 5.4 gave a reversal potential Erev of -50.4 ( 1.2 mV (n ) 7) (Figure 4), which was not significantly different from that of the wild type.
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ABCC7 p.Arg352His 10220340:160:57
status: NEW164 These uncharged substitutions also shifted the reversal potential by an amount comparable to that observed by deprotonating R352H; Erev ) -34.9 ( 2 mV (n ) 7) for R352C, and Erev ) -26.3 ( 1.9 mV (n ) 9) for R352Q (Figure 6), resulting in calculated PCl/PNa ratios of 7 (range of 6-8) and 4 (range of 3.5-4.4), respectively.
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ABCC7 p.Arg352His 10220340:164:124
status: NEW221 In the R352H mutant, at a cytoplasmic pH of 5.4 when the histidine is mostly protonated, PCl/PNa ) 33, similar to that of the wild type.
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ABCC7 p.Arg352His 10220340:221:7
status: NEW240 Thus, for the R352H mutant, we infer that the effect of the change in cytoplasmic pH on the Cl- to Na+ permeability ratio is due to a change in the protonation state of the histidine at position 352.5 Similarly, eliminating the positive charge at position 352 by substituting the uncharged amino acids, cysteine or glutamine, reduced PCl/PNa to about 5 (Figure 6).
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ABCC7 p.Arg352His 10220340:240:14
status: NEW278 In contrast, in the R352H mutant raising the pH, presumably deprotonating His352, caused a 10-fold reduction in the Cl- to Na+ permeability ratio.
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ABCC7 p.Arg352His 10220340:278:20
status: NEW279 The fact that substituting other uncharged residues, glutamine and cysteine, at position 352 caused similar changes in the Cl- to Na+ permeability ratio supports our inference that raising the bath pH reduces the charge selectivity of R352H by deprotonation of the histidine at position 352. ability sequence.
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ABCC7 p.Arg352His 10220340:279:235
status: NEW
PMID: 11585852
[PubMed]
Smith SS et al: "CFTR: covalent and noncovalent modification suggests a role for fixed charges in anion conduction."
No.
Sentence
Comment
148
Changes of this magnitude are also seen in oocytes expressing R352Q or R352H CFTR, but were not seen in oocytes expressing wt CFTR.
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ABCC7 p.Arg352His 11585852:148:71
status: NEW154 Importantly, we also obtained a transient response to the application of MTSEA in oocytes expressing R352Q CFTR (Fig. 5 C) or R352H CFTR (unpublished data).
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ABCC7 p.Arg352His 11585852:154:126
status: NEW
PMID: 19754156
[PubMed]
Alexander C et al: "Cystic fibrosis transmembrane conductance regulator: using differential reactivity toward channel-permeant and channel-impermeant thiol-reactive probes to test a molecular model for the pore."
No.
Sentence
Comment
182
In those experiments, however, qualitatively identical, reversible reactivity toward MTSEAþ was also seen using either R352Q/wt or R352H/wt CFTR constructs, suggesting that the target of MTSEAþ was 1 of the 18 endogenous cysteines in the R352C/wt protein (7).
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ABCC7 p.Arg352His 19754156:182:136
status: NEW