PMID: 9729613

Linsdell P, Zheng SX, Hanrahan JW
Non-pore lining amino acid side chains influence anion selectivity of the human CFTR Cl- channel expressed in mammalian cell lines.
J Physiol. 1998 Oct 1;512 ( Pt 1):1-16., 1998-10-01 [PubMed]
Sentences
No. Mutations Sentence Comment
20 ABCC7 p.Thr339Val
X
ABCC7 p.Thr339Val 9729613:20:12
status: NEW
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One mutant, T339V, was characterized in detail; its permeation properties were significantly altered, although these effects were not as strong as for T338 mutations. Login to comment
59 ABCC7 p.Thr338Phe
X
ABCC7 p.Thr338Phe 9729613:59:204
status: NEW
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Stable expression of all six T338 mutants constructed in BHK cells led to the production of both core-glycosylated (band B) and fully glycosylated (band C) CFTR protein, although some mutants (especially T338F) P. Linsdell, S.-X. Zheng and J. W. Hanrahan J. Physiol. 512.12 ) at UNIV OF NORTH CAROLINA on August 8, consistently made less band C protein than wild-type (Fig. 1C). Login to comment
60 ABCC7 p.Thr339Val
X
ABCC7 p.Thr339Val 9729613:60:55
status: NEW
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In contrast, of five mutations made at T339, only one (T339V) produced detectable levels of CFTR protein in Western blots using cell lysates from one confluent 10 cm culture plate (approximately 2 ² 10É-3 ² 10É cells; Fig. 1D). Login to comment
61 ABCC7 p.Thr339Ser
X
ABCC7 p.Thr339Ser 9729613:61:106
status: NEW
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However, following immunoprecipitation of CFTR protein from five confluent plates, a very small amount of T339S mutant CFTR protein was detectable by Western blotting (Fig. 1E), indicating that the BHK cells had been successfully transfected with the mutated plasmid, but that most mutations at T339 caused more severe misprocessing andÏor degradation of the CFTR protein. Login to comment
63 ABCC7 p.Thr338Phe
X
ABCC7 p.Thr338Phe 9729613:63:125
status: NEW
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In contrast, no currents were activated under these conditions in large inside-out patches excised from BHK cells expressing T338F (n = 8; not shown). Login to comment
81 ABCC7 p.Thr339Ser
X
ABCC7 p.Thr339Ser 9729613:81:38
status: NEW
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E, Western blot of immunoprecipitated T339S protein, carried out as described in Methods. Login to comment
82 ABCC7 p.Thr339Ala
X
ABCC7 p.Thr339Ala 9729613:82:35
status: NEW
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ABCC7 p.Thr339Phe
X
ABCC7 p.Thr339Phe 9729613:82:52
status: NEW
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ABCC7 p.Thr339Tyr
X
ABCC7 p.Thr339Tyr 9729613:82:42
status: NEW
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Similar results were observed with T339A, T339Y and T339F (not shown). Login to comment
84 ABCC7 p.Thr338Asn
X
ABCC7 p.Thr338Asn 9729613:84:217
status: NEW
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Example macroscopic current-voltage relationships for wild-type and T338 mutant CFTRs, recorded with symmetrical Cl¦-containing solutions Note the inward rectification observed with some T338 mutants, especially T338N. Login to comment
91 ABCC7 p.Thr338Ala
X
ABCC7 p.Thr338Ala 9729613:91:125
status: NEW
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ABCC7 p.Thr338Ala
X
ABCC7 p.Thr338Ala 9729613:91:126
status: NEW
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Significant rectification resulting in a -I+50ÏI-0 ratio significantly less than one was observed in all mutants except T338A (Fig. 3). Login to comment
92 ABCC7 p.Thr338Asn
X
ABCC7 p.Thr338Asn 9729613:92:41
status: NEW
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Rectification was particularly strong in T338N (-I+ 50ÏI-50 = 0·33 ± 0·05; n = 6). Login to comment
93 ABCC7 p.Thr338Ala
X
ABCC7 p.Thr338Ala 9729613:93:103
status: NEW
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ABCC7 p.Thr338Ser
X
ABCC7 p.Thr338Ser 9729613:93:112
status: NEW
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Single CFTR channel currents in inside-out patches excised from CHO cells stably expressing wild-type, T338A or T338S are shown in Fig. 4A. Login to comment
94 ABCC7 p.Thr338Ile
X
ABCC7 p.Thr338Ile 9729613:94:79
status: NEW
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ABCC7 p.Thr338Asn
X
ABCC7 p.Thr338Asn 9729613:94:63
status: NEW
view ABCC7 p.Thr338Asn details
ABCC7 p.Thr338Val
X
ABCC7 p.Thr338Val 9729613:94:70
status: NEW
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However, clear single channel currents were never resolved for T338N, T338V or T338I, either in CHO cell patches or in patches excised from BHK cells selected using a lower concentration of MTX (20 ìÒ), at potentials as hyperpolarized as -100 mV (data not shown). Login to comment
97 ABCC7 p.Thr338Ala
X
ABCC7 p.Thr338Ala 9729613:97:137
status: NEW
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ABCC7 p.Thr338Ser
X
ABCC7 p.Thr338Ser 9729613:97:188
status: NEW
view ABCC7 p.Thr338Ser details
Mean slope conductance was increased from 7·9 ± 0·1 pS (n = 18) for wild-type to 10·4 ± 0·1 pS (n = 9) for T338A and 11·3 ± 0·2 pS (n = 5) for T338S. Login to comment
99 ABCC7 p.Thr338Ala
X
ABCC7 p.Thr338Ala 9729613:99:23
status: NEW
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ABCC7 p.Thr338Ser
X
ABCC7 p.Thr338Ser 9729613:99:33
status: NEW
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Although the gating of T338A and T338S channels was not studied in detail, no striking differences from wild-type were noted. Login to comment
101 ABCC7 p.Thr338Ile
X
ABCC7 p.Thr338Ile 9729613:101:74
status: NEW
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ABCC7 p.Thr338Asn
X
ABCC7 p.Thr338Asn 9729613:101:57
status: NEW
view ABCC7 p.Thr338Asn details
ABCC7 p.Thr338Val
X
ABCC7 p.Thr338Val 9729613:101:64
status: NEW
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We attempted to make some estimate of the conductance of T338N, T338V and T338I channels by analysing the increase in current noise associated with macroscopic current activation (Fig. 5). Login to comment
107 ABCC7 p.Thr338Ala
X
ABCC7 p.Thr338Ala 9729613:107:22
status: NEW
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ABCC7 p.Thr338Ala
X
ABCC7 p.Thr338Ala 9729613:107:97
status: NEW
view ABCC7 p.Thr338Ala details
ABCC7 p.Thr338Ser
X
ABCC7 p.Thr338Ser 9729613:107:32
status: NEW
view ABCC7 p.Thr338Ser details
ABCC7 p.Thr338Ser
X
ABCC7 p.Thr338Ser 9729613:107:107
status: NEW
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Unitary properties of T338A and T338S CFTR A, examples of single channel activity for wild-type, T338A and T338S, recorded at -50 mV. Login to comment
109 ABCC7 p.Thr338Ala
X
ABCC7 p.Thr338Ala 9729613:109:74
status: NEW
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ABCC7 p.Thr338Ser
X
ABCC7 p.Thr338Ser 9729613:109:88
status: NEW
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B and C, mean single channel current-voltage relationships for wild-type, T338A (B) and T338S (C). Login to comment
111 ABCC7 p.Thr338Ile
X
ABCC7 p.Thr338Ile 9729613:111:52
status: NEW
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ABCC7 p.Thr338Asn
X
ABCC7 p.Thr338Asn 9729613:111:78
status: NEW
view ABCC7 p.Thr338Asn details
ABCC7 p.Thr338Val
X
ABCC7 p.Thr338Val 9729613:111:88
status: NEW
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In contrast to wild-type, activation of macroscopic T338I (Fig. 5C and D) and T338N and T338V (data not shown) Cl¦ currents was associated with only a very small increase in noise. Login to comment
112 ABCC7 p.Thr338Ile
X
ABCC7 p.Thr338Ile 9729613:112:228
status: NEW
view ABCC7 p.Thr338Ile details
ABCC7 p.Thr338Asn
X
ABCC7 p.Thr338Asn 9729613:112:126
status: NEW
view ABCC7 p.Thr338Asn details
ABCC7 p.Thr338Val
X
ABCC7 p.Thr338Val 9729613:112:175
status: NEW
view ABCC7 p.Thr338Val details
Analysis of current variance (e.g. Fig. 5D) yielded chord conductances at -50 mV of 0·23 ± 0·02 pS (n = 4) for T338N, 0·36 ± 0·10 pS (n = 5) for T338V, and 0·17 ± 0·04 pS (n = 5) for T338I. Login to comment
118 ABCC7 p.Thr338Phe
X
ABCC7 p.Thr338Phe 9729613:118:102
status: NEW
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Thus, the lack of macroscopic Cl¦ currents in membrane patches excised from BHK cells expressing T338F (see above) may reflect a non-conducting phenotype for this mutant. Login to comment
119 ABCC7 p.Thr338Phe
X
ABCC7 p.Thr338Phe 9729613:119:47
status: NEW
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Alternatively, misprocessing or degradation of T338F protein (Fig. 1C) may result in expression levels below our threshold of detection using patch clamp recording. Login to comment
121 ABCC7 p.Thr338Ile
X
ABCC7 p.Thr338Ile 9729613:121:0
status: NEW
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T338I gave only very small currents when intracellular Cl¦ was replaced by other anions, such that accurate measurement of Vrev was not possible, and therefore the selectivity of this mutant was not studied further. Login to comment
123 ABCC7 p.Thr338Ile
X
ABCC7 p.Thr338Ile 9729613:123:242
status: NEW
view ABCC7 p.Thr338Ile details
Estimation of unitary current amplitude from macroscopic current noise A and C, activation of macroscopic CFTR current at -50 mV is associated with a large increase in current noise for wild-type (A), but a much smaller increase in noise for T338I (C). Login to comment
142 ABCC7 p.Thr338Ala
X
ABCC7 p.Thr338Ala 9729613:142:154
status: NEW
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ABCC7 p.Thr338Ser
X
ABCC7 p.Thr338Ser 9729613:142:160
status: NEW
view ABCC7 p.Thr338Ser details
ABCC7 p.Thr339Val
X
ABCC7 p.Thr339Val 9729613:142:178
status: NEW
view ABCC7 p.Thr339Val details
ABCC7 p.Thr338Asn
X
ABCC7 p.Thr338Asn 9729613:142:166
status: NEW
view ABCC7 p.Thr338Asn details
ABCC7 p.Thr338Val
X
ABCC7 p.Thr338Val 9729613:142:172
status: NEW
view ABCC7 p.Thr338Val details
Permeability of intracellular anions in wild-type and mutant CFTR Cl¦ channels ------------------------------------------------------------ Anion WT T338A T338S T338N T338V T339V ------------------------------------------------------------ Thiocyanate 2·63 ± 0·13 (6) 5·85 ± 0·27 (4)* 4·80 ± 0·19 (3)* 8·72 ± 1·03 (4)* 1·92 ± 0·35 (4)* 3·28 ± 0·08 (4)* Nitrate 1·53 ± 0·04 (7) 2·04 ± 0·08 (3)* 1·82 ± 0·03 (4)* 4·22 ± 0·22 (3)* 6·84 ± 1·18 (7)* 1·61 ± 0·02 (3) Bromide 1·23 ± 0·03 (5) 1·74 ± 0·04 (3)* 1·47 ± 0·07 (3)* 1·66 ± 0·15 (3)* 1·04 ± 0·09 (5) 1·39 ± 0·06 (4)* Chloride 1·00 ± 0·01 (10) 1·00 ± 0·02 (11) 1·00 ± 0·02 (6) 1·00 ± 0·03 (10) 1·00 ± 0·04 (11) 1·00 ± 0·06 (10) Iodide 0·84 ± 0·03 (5) 2·09 ± 0·16 (5)* 1·76 ± 0·09 (3)* 1·03 ± 0·05 (3)* 0·79 ± 0·11 (3) 0·84 ± 0·02 (3) Perchlorate 0·25 ± 0·02 (6) 1·35 ± 0·08 (3)* 0·66 ± 0·06 (3)* 0·41 ± 0·03 (3)* 0·54 ± 0·00 (3)* 0·24 ± 0·01 (4) Benzoate 0·069 ± 0·006 (6) 0·17 ± 0·03 (4)* 0·091 ± 0·019 (3) 0·089 ± 0·015 (4) 0·15 ± 0·02 (4)* 0·097 ± 0·014 (4) Hexafluorophosphate < 0·019 (4) 0·53 ± 0·01 (3)* 0·31 ± 0·02 (3)* 0·68 ± 0·02 (3)* 0·39 ± 0·05 (3)* 0·051 ± 0·010 (4)* Fluoride 0·11 ± 0·01 (7) 0·12 ± 0·02 (4) 0·095 ± 0·012 (4) 0·11 ± 0·01 (4) 0·093 ± 0·009 (3) 0·17 ± 0·02 (4)* Formate 0·25 ± 0·01 (8) 0·45 ± 0·04 (3)* 0·43 ± 0·03 (3)* 0·35 ± 0·04 (4)* 0·22 ± 0·01 (3) 0·28 ± 0·02 (3) Acetate 0·090 ± 0·004 (8) 0·19 ± 0·01 (3)* 0·18 ± 0·01 (3)* 0·10 ± 0·02 (5) 0·11 ± 0·02 (3) 0·16 ± 0·01 (3)* Propanoate 0·14 ± 0·01 (3) 0·18 ± 0·02 (4) 0·098 ± 0·010 (4)* 0·077 ± 0·013 (3)* 0·13 ± 0·02 (3) - Pyruvate 0·10 ± 0·01 (5) 0·20 ± 0·01 (3)* 0·13 ± 0·02 (3) 0·075 ± 0·015 (3) 0·17 ± 0·03 (3)* - Methane sulphonate 0·077 ± 0·005 (5) 0·14 ± 0·02 (4)* 0·079 ± 0·014 (3) 0·038 ± 0·004 (3)* 0·088 ± 0·007 (3) - Glutamate 0·096 ± 0·008 (4) 0·082 ± 0·009 (3) 0·080 ± 0·008 (3) 0·060 ± 0·012 (5)* 0·11 ± 0·01 (3) - Isethionate 0·13 ± 0·01 (4) 0·11 ± 0·01 (3) 0·086 ± 0·012 (5)* 0·043 ± 0·007 (3)* 0·067 ± 0·005 (3)* - Gluconate 0·068 ± 0·004 (36) 0·10 ± 0·01 (3)* 0·060 ± 0·004 (3) 0·044 ± 0·004 (3) 0·077 ± 0·009 (3) 0·088 ± 0·021 (5) ------------------------------------------------------------ Relative permeabilities of different anions present in the intracellular solution under biionic conditions were calculated from macroscopic current reversal potentials (e.g. Figs 7 and 10) as described in Methods. Login to comment
150 ABCC7 p.Thr338Ala
X
ABCC7 p.Thr338Ala 9729613:150:64
status: NEW
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ABCC7 p.Thr338Ser
X
ABCC7 p.Thr338Ser 9729613:150:72
status: NEW
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Note that all lyotropic anions showed the permeability sequence T338A > T338S > wild-type, again suggesting that the effects of these mutations on pore properties are correlated with the size of the amino acid side chain substituted. Login to comment
151 ABCC7 p.Thr338Asn
X
ABCC7 p.Thr338Asn 9729613:151:59
status: NEW
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ABCC7 p.Thr338Val
X
ABCC7 p.Thr338Val 9729613:151:69
status: NEW
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However, the permeabilities of the low conductance mutants T338N and T338V were more difficult to interpret, possibly indicating that substitution of a larger amino acid for T338 causes a more severe disruption of pore function. Login to comment
153 ABCC7 p.Thr338Ala
X
ABCC7 p.Thr338Ala 9729613:153:599
status: NEW
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ABCC7 p.Thr338Ser
X
ABCC7 p.Thr338Ser 9729613:153:724
status: NEW
view ABCC7 p.Thr338Ser details
ABCC7 p.Thr338Asn
X
ABCC7 p.Thr338Asn 9729613:153:849
status: NEW
view ABCC7 p.Thr338Asn details
ABCC7 p.Thr338Val
X
ABCC7 p.Thr338Val 9729613:153:969
status: NEW
view ABCC7 p.Thr338Val details
Pore diameter of T338 mutants Previously, we suggested that the double mutant channel, TT338,339AA, had an increased minimum functional pore diameter, based on its increased permeability to extracellular formate, acetate, propanoate and pyruvate ions (Linsdell et P. Linsdell, S.-X. Zheng and J. W. Hanrahan J. Physiol. 512.18 -------------------------------------------------------------------------------------------- Table 2 ---------------------------------------------- Wild-type SCN¦ > NOצ > Br¦ > Cl¦ > I¦ > ClOÚ¦ > formate > F¦ > PFܦ T338A SCN¦ > I¦ ü NOצ > Br¦ > ClOÚ¦ > Cl¦ > PFܦ > formate > F¦ T338S SCN¦ > NOצ ü I¦ > Br¦ > Cl¦ > ClOÚ¦ > formate > PFܦ > F¦ T338N SCN¦ > NOצ > Br¦ > I¦ = Cl¦ > PFܦ > ClOÚ¦ > formate > F¦ T338V NOצ > SCN¦ > Br¦ = Cl¦ > I¦ > ClOÚ¦ > PFܦ > formate > F¦ -------------------------------------------------------------------------------------------- Figure 7. Login to comment
164 ABCC7 p.Thr338Ala
X
ABCC7 p.Thr338Ala 9729613:164:137
status: NEW
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ABCC7 p.Thr338Ser
X
ABCC7 p.Thr338Ser 9729613:164:160
status: NEW
view ABCC7 p.Thr338Ser details
ABCC7 p.Thr338Asn
X
ABCC7 p.Thr338Asn 9729613:164:183
status: NEW
view ABCC7 p.Thr338Asn details
ABCC7 p.Thr338Val
X
ABCC7 p.Thr338Val 9729613:164:209
status: NEW
view ABCC7 p.Thr338Val details
In each case the data have been fitted by eqn (2), giving minimum functional pore diameters of 0·528 nm (wild-type), 0·576 nm (T338A), 0·549 nm (T338S), 0·510 nm (T338N) and 0·540 nm (T338V). Login to comment
168 ABCC7 p.Thr338Ala
X
ABCC7 p.Thr338Ala 9729613:168:171
status: NEW
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ABCC7 p.Thr338Ser
X
ABCC7 p.Thr338Ser 9729613:168:196
status: NEW
view ABCC7 p.Thr338Ser details
ABCC7 p.Thr338Asn
X
ABCC7 p.Thr338Asn 9729613:168:221
status: NEW
view ABCC7 p.Thr338Asn details
ABCC7 p.Thr338Val
X
ABCC7 p.Thr338Val 9729613:168:249
status: NEW
view ABCC7 p.Thr338Val details
In each case the data have been fitted using eqn (2) (see Methods), giving estimates of the functional pore diameter (d) of 0·528 nm for wild-type, 0·576 nm for T338A, 0·549 nm for T338S, 0·510 nm for T338N and 0·540 nm for T338V. Anions examined (in order of increasing diameter) were: SCN¦, Cl¦, NOצ, Br¦, I¦, ClOÚ¦, benzoate and PFܦ. Login to comment
171 ABCC7 p.Thr338Ala
X
ABCC7 p.Thr338Ala 9729613:171:108
status: NEW
view ABCC7 p.Thr338Ala details
ABCC7 p.Thr338Ser
X
ABCC7 p.Thr338Ser 9729613:171:131
status: NEW
view ABCC7 p.Thr338Ser details
ABCC7 p.Thr338Asn
X
ABCC7 p.Thr338Asn 9729613:171:154
status: NEW
view ABCC7 p.Thr338Asn details
ABCC7 p.Thr338Val
X
ABCC7 p.Thr338Val 9729613:171:180
status: NEW
view ABCC7 p.Thr338Val details
In this case, fits by eqn (2) suggested minimum pore diameters of 0·535 nm (wild-type), 0·615 nm (T338A), 0·505 nm (T338S), 0·503 nm (T338N) and 0·530 nm (T338V). Login to comment
173 ABCC7 p.Thr339Val
X
ABCC7 p.Thr339Val 9729613:173:101
status: NEW
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Effects of mutations at T339 Of five amino acid substitutions carried out at position 339, only one (T339V) resulted in the production of detectable amounts of CFTR protein (Fig. 1D). Login to comment
174 ABCC7 p.Thr339Ala
X
ABCC7 p.Thr339Ala 9729613:174:117
status: NEW
view ABCC7 p.Thr339Ala details
ABCC7 p.Thr339Ala
X
ABCC7 p.Thr339Ala 9729613:174:119
status: NEW
view ABCC7 p.Thr339Ala details
ABCC7 p.Thr339Ser
X
ABCC7 p.Thr339Ser 9729613:174:132
status: NEW
view ABCC7 p.Thr339Ser details
ABCC7 p.Thr339Ser
X
ABCC7 p.Thr339Ser 9729613:174:134
status: NEW
view ABCC7 p.Thr339Ser details
ABCC7 p.Thr339Phe
X
ABCC7 p.Thr339Phe 9729613:174:164
status: NEW
view ABCC7 p.Thr339Phe details
ABCC7 p.Thr339Phe
X
ABCC7 p.Thr339Phe 9729613:174:166
status: NEW
view ABCC7 p.Thr339Phe details
ABCC7 p.Thr339Tyr
X
ABCC7 p.Thr339Tyr 9729613:174:147
status: NEW
view ABCC7 p.Thr339Tyr details
ABCC7 p.Thr339Tyr
X
ABCC7 p.Thr339Tyr 9729613:174:149
status: NEW
view ABCC7 p.Thr339Tyr details
Indeed, we found no PKAand ATP-dependent currents in very large inside-out patches excised from BHK cells expressing T339A (n = 6), T339S (n = 4), T339Y (n = 6) or T339F (n = 5) using symmetrical 150 mÒ NaCl-containing solutions (not shown). Login to comment
175 ABCC7 p.Thr339Val
X
ABCC7 p.Thr339Val 9729613:175:76
status: NEW
view ABCC7 p.Thr339Val details
ABCC7 p.Thr339Val
X
ABCC7 p.Thr339Val 9729613:175:78
status: NEW
view ABCC7 p.Thr339Val details
PKAand ATP-dependent currents were observed, however, in twelve of fourteen T339V CFTR patches under the same conditions (Fig. 10A). Login to comment
176 ABCC7 p.Thr339Val
X
ABCC7 p.Thr339Val 9729613:176:0
status: NEW
view ABCC7 p.Thr339Val details
T339V showed slight inward current rectification under these symmetrical ionic conditions (-I+50ÏI-50 = 0·86 ± 0·01; n = 8). Login to comment
178 ABCC7 p.Thr339Val
X
ABCC7 p.Thr339Val 9729613:178:28
status: NEW
view ABCC7 p.Thr339Val details
Mean chord conductances for T339V were 7·95 ± 0·16 pS (n = 4) at -50 mV and 6·37 ± 0·29 pS (n = 3) at +50 mV, compared with wild-type values of 7·91 ± 0·09 pS (n = 18) at -50 mV and 7·85 ± 0·09 pS (n = 12) at +50 mV. Login to comment
179 ABCC7 p.Thr338Ala
X
ABCC7 p.Thr338Ala 9729613:179:8
status: NEW
view ABCC7 p.Thr338Ala details
ABCC7 p.Thr338Ser
X
ABCC7 p.Thr338Ser 9729613:179:18
status: NEW
view ABCC7 p.Thr338Ser details
ABCC7 p.Thr339Val
X
ABCC7 p.Thr339Val 9729613:179:25
status: NEW
view ABCC7 p.Thr339Val details
As with T338A and T338S, T339V showed apparently normal channel gating, with open probability being time and P. Linsdell, S.-X. Zheng and J. W. Hanrahan J. Physiol. 512.110 Figure 9. Login to comment
181 ABCC7 p.Thr338Ala
X
ABCC7 p.Thr338Ala 9729613:181:171
status: NEW
view ABCC7 p.Thr338Ala details
ABCC7 p.Thr338Ser
X
ABCC7 p.Thr338Ser 9729613:181:196
status: NEW
view ABCC7 p.Thr338Ser details
ABCC7 p.Thr338Asn
X
ABCC7 p.Thr338Asn 9729613:181:221
status: NEW
view ABCC7 p.Thr338Asn details
ABCC7 p.Thr338Val
X
ABCC7 p.Thr338Val 9729613:181:249
status: NEW
view ABCC7 p.Thr338Val details
In each case the data have been fitted using eqn (2) (see Methods), giving estimates of the functional pore diameter (d) of 0·535 nm for wild type, 0·615 nm for T338A, 0·505 nm for T338S, 0·503 nm for T338N and 0·530 nm for T338V. Anions examined (in order of increasing diameter) were: formate, acetate, propanoate, pyruvate, methane sulphonate and gluconate.) Login to comment
183 ABCC7 p.Thr339Val
X
ABCC7 p.Thr339Val 9729613:183:35
status: NEW
view ABCC7 p.Thr339Val details
Furthermore, as with T338 mutants, T339V had negligible cation permeability (data not shown). Login to comment
184 ABCC7 p.Thr339Val
X
ABCC7 p.Thr339Val 9729613:184:4
status: NEW
view ABCC7 p.Thr339Val details
The T339V mutant also had significant alterations in ionic permeability (Fig. 10B and Table 1), although in general these were not as strong as those observed for T338 mutants. Login to comment
185 ABCC7 p.Thr339Val
X
ABCC7 p.Thr339Val 9729613:185:37
status: NEW
view ABCC7 p.Thr339Val details
Indeed, the selectivity sequence for T339V (SCN¦ > NOצ > Br¦ > Cl¦ > I¦ > ClOÚ¦ > formate > F¦ > PFܦ) was the same as for wild-type (see Table 2). Login to comment
186 ABCC7 p.Thr339Val
X
ABCC7 p.Thr339Val 9729613:186:56
status: NEW
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Gluconate permeability was not significantly altered in T339V, again suggesting no severe disruption of large organic anion permeability. Login to comment
187 ABCC7 p.Thr339Val
X
ABCC7 p.Thr339Val 9729613:187:45
status: NEW
view ABCC7 p.Thr339Val details
All of these effects are consistent with the T339V mutant having less severely altered pore properties than any of the T338 mutants studied. Login to comment
193 ABCC7 p.Thr338Ile
X
ABCC7 p.Thr338Ile 9729613:193:156
status: NEW
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ABCC7 p.Thr338Asn
X
ABCC7 p.Thr338Asn 9729613:193:139
status: NEW
view ABCC7 p.Thr338Asn details
ABCC7 p.Thr338Val
X
ABCC7 p.Thr338Val 9729613:193:146
status: NEW
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The conductance of different T338 mutants varied over almost two orders of magnitude (Fig. 6), although the low conductances estimated for T338N, T338V and T338I should be considered rough approximations only. Login to comment
195 ABCC7 p.Thr338Ile
X
ABCC7 p.Thr338Ile 9729613:195:175
status: NEW
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The central portion of TM6 containing both of these key amino acids (T338 and S341) may therefore be the region where conductance is mainly determined. The low conductance of T338I could also explain why this mutation is associated with CF (Saba et al. 1993), although partial misprocessing (Fig. 1C) may also play a role. Login to comment
196 ABCC7 p.Thr338Ala
X
ABCC7 p.Thr338Ala 9729613:196:40
status: NEW
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ABCC7 p.Thr338Ser
X
ABCC7 p.Thr338Ser 9729613:196:50
status: NEW
view ABCC7 p.Thr338Ser details
Conversely, the elevated conductance of T338A and T338S might be advantageous in gene or protein replacement therapies for Alteration of CFTR anion selectivityJ. Physiol. 512.1 11 Figure 10. Login to comment
197 ABCC7 p.Thr339Val
X
ABCC7 p.Thr339Val 9729613:197:46
status: NEW
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ABCC7 p.Thr339Val
X
ABCC7 p.Thr339Val 9729613:197:60
status: NEW
view ABCC7 p.Thr339Val details
Macroscopic current-voltage relationships for T339V CFTR A, T339V shows slight inward rectification with symmetrical Cl¦-containing solutions. Login to comment
198 ABCC7 p.Thr339Val
X
ABCC7 p.Thr339Val 9729613:198:86
status: NEW
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B, example current-voltage relationships used to investigate the anion selectivity of T339V, measured under biionic conditions with ClOڦ or NOצ in the intracellular solution. Login to comment
199 ABCC7 p.Thr339Val
X
ABCC7 p.Thr339Val 9729613:199:44
status: NEW
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Note that the permeability of these ions in T339V is similar to that observed in wild-type (Fig. 7). Login to comment
205 ABCC7 p.Thr338Ala
X
ABCC7 p.Thr338Ala 9729613:205:20
status: NEW
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ABCC7 p.Thr338Ser
X
ABCC7 p.Thr338Ser 9729613:205:54
status: NEW
view ABCC7 p.Thr338Ser details
Interestingly, both T338A (10·4 pS; Fig. 4B) and T338S (11·3 pS; Fig. 4C) have higher conductances than that we reported previously for TT338,339AA (9·9 pS; Linsdell et al. 1997b). Login to comment
206 ABCC7 p.Thr338Ser
X
ABCC7 p.Thr338Ser 9729613:206:5
status: NEW
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Thus T338S has the highest conductance of any CFTR variant described to date. Login to comment
207 ABCC7 p.Thr338Ile
X
ABCC7 p.Thr338Ile 9729613:207:151
status: NEW
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ABCC7 p.Thr338Asn
X
ABCC7 p.Thr338Asn 9729613:207:134
status: NEW
view ABCC7 p.Thr338Asn details
ABCC7 p.Thr338Val
X
ABCC7 p.Thr338Val 9729613:207:141
status: NEW
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All single channel conductances reported in this paper were measured at hyperpolarized potentials; conductance of the mutant channels T338N, T338V and T338I might be significantly lower at depolarized potentials (Fig. 2). Login to comment
209 ABCC7 p.Lys335Glu
X
ABCC7 p.Lys335Glu 9729613:209:96
status: NEW
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ABCC7 p.Thr339Val
X
ABCC7 p.Thr339Val 9729613:209:128
status: NEW
view ABCC7 p.Thr339Val details
ABCC7 p.Ile332Lys
X
ABCC7 p.Ile332Lys 9729613:209:149
status: NEW
view ABCC7 p.Ile332Lys details
Inward rectification is observed in several other TM6 mutants at the single channel level, e.g. K335E (Tabcharani et al. 1993), T339V (Fig. 11B) and I332K (P. Linsdell, J. A. Tabcharani & J. W. Hanrahan, unpublished observations); however, voltage-dependent gating in T338 mutants cannot be excluded. Login to comment
222 ABCC7 p.Thr339Val
X
ABCC7 p.Thr339Val 9729613:222:22
status: NEW
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ABCC7 p.Thr339Val
X
ABCC7 p.Thr339Val 9729613:222:57
status: NEW
view ABCC7 p.Thr339Val details
Unitary properties of T339V CFTR A, activity of a single T339V channel at -50 mV (cf. Login to comment
224 ABCC7 p.Thr339Val
X
ABCC7 p.Thr339Val 9729613:224:93
status: NEW
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B, mean single channel current-voltage relationships for wild-type (as in Fig. 4B and C) and T339V. Login to comment
232 ABCC7 p.Thr338Ala
X
ABCC7 p.Thr338Ala 9729613:232:8
status: NEW
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Thus in T338A, for example, the relationship between permeability and ionic hydration energy appeared much more linear than for wild-type (Fig. 12B). Login to comment
237 ABCC7 p.Thr339Val
X
ABCC7 p.Thr339Val 9729613:237:162
status: NEW
view ABCC7 p.Thr339Val details
However, it is unclear why mutations at T339 should apparently be more sensitive to misprocessing than those at T338 (Fig. 1C and D), or why the non-conservative T339V mutation alone should be appropriately processed (Fig. 1D). Login to comment
238 ABCC7 p.Thr339Ala
X
ABCC7 p.Thr339Ala 9729613:238:5
status: NEW
view ABCC7 p.Thr339Ala details
ABCC7 p.Thr339Cys
X
ABCC7 p.Thr339Cys 9729613:238:39
status: NEW
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Both T339A (McDonough et al. 1994) and T339C (Cheung & Akabas, 1996) mutant channels can be expressed in Xenopus oocytes following injection of in vitro transcribed cRNA. Login to comment
239 ABCC7 p.Thr339Ala
X
ABCC7 p.Thr339Ala 9729613:239:171
status: NEW
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Furthermore, the double mutant TT338,339AA can be functionally expressed in CHO cells (Linsdell et al. 1997b), raising the possibility that the detrimental effects of the T339A mutation on processing may be 'rescued` by simultaneous mutation of T338. Login to comment
240 ABCC7 p.Thr339Val
X
ABCC7 p.Thr339Val 9729613:240:115
status: NEW
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Because of low protein expression, we were only able to characterize the permeation properties of one T339 mutant, T339V. Login to comment
242 ABCC7 p.Thr338Ala
X
ABCC7 p.Thr338Ala 9729613:242:124
status: NEW
view ABCC7 p.Thr338Ala details
Relationship between relative permeability and free energy of hydration for different intracellular anions A, wild-type; B, T338A. Login to comment