ABCMdb

ABCC7 p.Thr338Ser

None has been submitted yet.

Publications

PMID: 11179391 [PubMed] Linsdell P et al: "Relationship between anion binding and anion permeability revealed by mutagenesis within the cystic fibrosis transmembrane conductance regulator chloride channel pore."

No. Sentence Comment

264 Optimization of Cl¦ conductance, rather than Cl¦ permeability, is likely to be of greater importance to the physiological function of CFTR and other Cl¦ channels, although in CFTR the mutations T338A and T338S increase Cl¦ conductance, apparently without adversely affecting other channel properties (Linsdell et al. 1998). Login to comment

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

No. Sentence Comment

114 T338C CFTR undergoes pH-dependent changes in gCl and I-V shape that are not seen in wild type, T338A or T338S CFTR. Login to comment

PMID: 16436375 [PubMed] Liu X et al: "Variable reactivity of an engineered cysteine at position 338 in cystic fibrosis transmembrane conductance regulator reflects different chemical states of the thiol."

No. Sentence Comment

53 RESULTS T338C/WT CFTR Conductance Was Markedly Altered by 2-ME or DTT Prior to Exposure to Exogenous Thiol-directed Reagents5 - Exposing oocytes expressing T338C/WT CFTR to 2-ME or DTT during steady state activation led to increases in conductance (without any discernable change in reversal potential) that were rapid (t1/2 ϭ 20 s), and of variable amplitude and were not seen in oocytes expressing CFTR constructs lacking the cysteine at 338, such as WT, T338A, T338H, T338S CFTR, or Cys-less CFTR. Login to comment
102 This 6 Similarly, exposure to reducing agents was without effect on oocytes expressing either T338A or T338S CFTR, constructs that retain the 18 endogenous cysteines (see below). Login to comment
111 It should be noted that the cysteine at position 338 is essential for the effects of MTS reagents as well as 2-ME and DTT shown above, because neither the conductance due to T338A or T338S CFTR was sensitive to reducing agents or thiol-directed reagents.7 Trapping Thiols with an Alkylating Agent, IAM-The results presented so far are compatible with a scheme in which the total conductance of an oocyte expressing T338C/WT CFTR or T338C/Cys-less CFTR comprises at least three components that we will label as gSH, gSX1, and gSX2, where the total conductance, gCl, is given by Equation 1. gCl ϭ gSH ϩ gSX1 ϩ gSX2 (Eq. 1) 7 X. Liu and D. C. Dawson, unpublished observation. Login to comment
200 Up to 14 mM H2O2 had no discernable effect on conductance of oocytes expressing T338S or WT CFTR.7 Low Concentrations of Copper Mimicked the gSX1 Phenotype-Metals like iron, zinc, and copper that react with free thiols are abundant in Xeno- FIGURE 6. Login to comment

PMID: 9729613 [PubMed] Linsdell P et al: "Non-pore lining amino acid side chains influence anion selectivity of the human CFTR Cl- channel expressed in mammalian cell lines."

No. Sentence Comment

93 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
97 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 Although the gating of T338A and T338S channels was not studied in detail, no striking differences from wild-type were noted. Login to comment
107 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 B and C, mean single channel current-voltage relationships for wild-type, T338A (B) and T338S (C). Login to comment
142 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 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
153 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¦ > NO×¦ > Br¦ > Cl¦ > I¦ > ClOÚ¦ > formate > F¦ > PFÜ¦ T338A SCN¦ > I¦ ü NO×¦ > Br¦ > ClOÚ¦ > Cl¦ > PFÜ¦ > formate > F¦ T338S SCN¦ > NO×¦ ü I¦ > Br¦ > Cl¦ > ClOÚ¦ > formate > PFÜ¦ > F¦ T338N SCN¦ > NO×¦ > Br¦ > I¦ = Cl¦ > PFÜ¦ > ClOÚ¦ > formate > F¦ T338V NO×¦ > SCN¦ > Br¦ = Cl¦ > I¦ > ClOÚ¦ > PFÜ¦ > formate > F¦ -------------------------------------------------------------------------------------------- Figure 7. Login to comment
164 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 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¦, NO×¦, Br¦, I¦, ClOÚ¦, benzoate and PFÜ¦. Login to comment
171 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
179 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 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
196 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
205 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 Thus T338S has the highest conductance of any CFTR variant described to date. Login to comment

PMID: 15361410 [PubMed] Liu X et al: "CFTR: a cysteine at position 338 in TM6 senses a positive electrostatic potential in the pore."

No. Sentence Comment

124 Changing the bath pH had essentially no effect on the conductances of oocytes expressing T338A CFTR (Fig. 2 C, n ¼ 3), nor did the same maneuver alter the conductances of oocytes expressing T338S (Fig. 3) or wt CFTR (Smith et al., 2001), consistent with the idea that the pH-dependent change in conductance of T338C CFTR was due to the titration of the cysteine substituted at 338. Login to comment
125 As an additional test of the hypothesis that the pH-induced response seen in T338C CFTR was due to the titration of the engineered cysteine, we exposed oocytes expressing T338C CFTR to NEM, a reagent that forms a thioether bond with the cysteine, and thereby blocks titration of the thiol group. Login to comment
144 Oocytes expressing T338C or T338S CFTR were first exposed to a stimulatory cocktail containing 10 mM Isop and 1 mM IBMX at pH 7.4. Login to comment
149 T338S CFTR exhibited no pH-sensitivity. Login to comment
145 Oocytes expressing T338C or T338S CFTR were first exposed to a stimulatory cocktail containing 10 mM Isop and 1 mM IBMX at pH 7.4. Login to comment
150 T338S CFTR exhibited no pH-sensitivity. Login to comment