ABCC7 p.Arg975Cys
| Predicted by SNAP2: | A: D (91%), C: D (80%), D: D (95%), E: D (95%), F: D (91%), G: D (95%), H: D (91%), I: D (85%), K: D (91%), L: D (91%), M: D (85%), N: D (95%), P: D (95%), Q: D (91%), S: D (91%), T: D (91%), V: D (91%), W: D (95%), Y: D (95%), |
| Predicted by PROVEAN: | A: D, C: D, D: D, E: D, F: D, G: D, H: D, I: D, K: D, L: D, M: D, N: D, P: D, Q: D, S: D, T: D, V: D, W: D, Y: D, |
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[hide] Functional Architecture of the Cytoplasmic Entranc... J Biol Chem. 2015 Jun 19;290(25):15855-65. doi: 10.1074/jbc.M115.656181. Epub 2015 May 5. El Hiani Y, Linsdell P
Functional Architecture of the Cytoplasmic Entrance to the Cystic Fibrosis Transmembrane Conductance Regulator Chloride Channel Pore.
J Biol Chem. 2015 Jun 19;290(25):15855-65. doi: 10.1074/jbc.M115.656181. Epub 2015 May 5., [PMID:25944907]
Abstract [show]
As an ion channel, the cystic fibrosis transmembrane conductance regulator must form a continuous pathway for the movement of Cl(-) and other anions between the cytoplasm and the extracellular solution. Both the structure and the function of the membrane-spanning part of this pathway are well defined. In contrast, the structure of the pathway that connects the cytoplasm to the membrane-spanning regions is unknown, and functional roles for different parts of the protein forming this pathway have not been described. We used patch clamp recording and substituted cysteine accessibility mutagenesis to identify positively charged amino acid side chains that attract cytoplasmic Cl(-) ions to the inner mouth of the pore. Our results indicate that the side chains of Lys-190, Arg-248, Arg-303, Lys-370, Lys-1041, and Arg-1048, located in different intracellular loops of the protein, play important roles in the electrostatic attraction of Cl(-) ions. Mutation and covalent modification of these residues have charge-dependent effects on the rate of Cl(-) permeation, demonstrating their functional role in maximization of Cl(-) flux. Other nearby positively charged side chains were not involved in electrostatic interactions with Cl(-). The location of these Cl(-)-attractive residues suggests that cytoplasmic Cl(-) ions enter the pore via a lateral portal located between the cytoplasmic extensions to the fourth and sixth transmembrane helices; a secondary, functionally less relevant portal might exist between the extensions to the 10th and 12th transmembrane helices. These results define the cytoplasmic mouth of the pore and show how it attracts Cl(-) ions from the cytoplasm.
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No. Sentence Comment
109 Application of MTSES (200 òe;M) following channel activation with PKA and ATP never caused an increase in macroscopic current amplitude but decreased current amplitude in K190C, R248C, R251C, R303C, K370C, K946C, R975C, K1041C, and R1048C (Figs. 2 and 3).
X
ABCC7 p.Arg975Cys 25944907:109:217
status: NEW110 The effect of MTSET on these MTSES-sensitive mutants was to increase (K190C and R303C), decrease (R248C, K946C, K1041C, and R1048C), or have no effect (R251C, K370C, and R975C) on macroscopic current amplitude (Figs. 2 and 3).
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ABCC7 p.Arg975Cys 25944907:110:170
status: NEW114 The effects of MTS modification of side chains within the ICLs could reflect changes in Clafa; conductance (as suggested previously for R303C (19)) or in open probability (as shown previously for K946C and R975C (11)) or a combination of the two.
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ABCC7 p.Arg975Cys 25944907:114:209
status: NEW116 Results with R303C, K946C, and R975C, which as described above are expected to affect predominantly Clafa; conductance (R303C) or gating (K946C and R975C), suggest that use of PPi in this way can effectively separate effects on Clafa; conductance from those on gating.
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ABCC7 p.Arg975Cys 25944907:116:31
status: NEWX
ABCC7 p.Arg975Cys 25944907:116:151
status: NEW118 In contrast, the effects of MTS reagents on both K946C and R975C were lost following PPi treatment (Fig. 5), consistent with these reagents modifying the normal gating process (reducing channel open probability) without affecting Clafa; conductance (11).
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ABCC7 p.Arg975Cys 25944907:118:59
status: NEW126 As described previously (11) and consistent with results from macroscopic current recording following channel treatment with PPi (Fig. 5), application of MTSES or MTSET had no effect on current amplitude in K946C or R975C (Figs. 6 and 7).
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ABCC7 p.Arg975Cys 25944907:126:216
status: NEW141 Cytoplasmic Entrance to the CFTR Channel Pore 15860 JOURNAL OF BIOLOGICAL CHEMISTRY VOLUME 290ߦNUMBER 25ߦJUNE 19, 2015 at SEMMELWEIS UNIV OF MEDICINE on December 4, amplitudes in unmodified channels was Cys-less b; K946C b03; R975C b0e; K370C b0e; R251C b0e; K1041C b03; R248C b0e; R1048C b0e; R303C b0e; K190C (Fig. 7A).
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ABCC7 p.Arg975Cys 25944907:141:245
status: NEW164 Consistent with this, the functional effect of MTS reagents on R251C, K946C, and R975C were abolished in channels that had been treated with PPi to maintain the channels in the open state (Fig. 5).
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ABCC7 p.Arg975Cys 25944907:164:81
status: NEW165 This suggests that MTS modification of these mutants may have affected channel gating, leading to a change in overall macroscopic current amplitude (Fig. 3), as previously demonstrated directly for K946C and R975C using single channel recording (11).
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ABCC7 p.Arg975Cys 25944907:165:208
status: NEW170 Effects of both mutagenesis (12, 29-32) and MTS modification (including of K946C and R975C) (11) within the ICLs on channel gating have been reported previously; however, the mechanism(s) by which these manipulations of ICL structure affect channel gating is not well understood.
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ABCC7 p.Arg975Cys 25944907:170:85
status: NEW