ABCMdb

ABCC7 p.Arg1048Cys

CF databases:	c.3142A>G , p.Arg1048Gly (CFTR1) ? , The mutation was detected by DGGE analysis and characterized by direct sequencing. We have seen it only once, in over 2100 control chromosomes from Italian population.
Predicted by SNAP2:	A: D (59%), C: N (61%), D: D (85%), E: D (80%), F: D (71%), G: D (66%), H: D (63%), I: N (53%), K: D (53%), L: D (59%), M: N (61%), N: D (63%), P: D (80%), Q: N (61%), S: N (57%), T: D (53%), V: D (59%), W: D (75%), Y: D (71%),
Predicted by PROVEAN:	A: D, C: D, D: D, E: D, F: D, G: D, H: D, I: D, K: N, 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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103 A-D, examples of modification of four different mutants (A, R303C, used in this study as a positive control; B, K190C; C, K370C; D, R1048C) by MTSES (left panels) or MTSET (right panels). Login to 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). Login to comment
110 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). Login to comment
121 In contrast, the inhibitory effects of MTSES on K190C, R248C, K370C, and R1048C were preserved following PPi treatment (Figs. 4 and 5), suggesting that modification with this negatively charged reagent caused a major inhibition of Clafa; conductance in open channels in each of these mutants. Login to comment
122 Interestingly, in each of these four mutants, MTSET caused a significant increase in macroscopic current amplitude when applied after PPi treatment (Figs. 4 and 5) even though MTSET applied in the absence of PPi treatment decreased macroscopic current amplitude in R248C, K370C, and R1048C (Figs. 4 and 5). Login to comment
123 This implies that modification with positively charged MTSET caused an increase in Clafa; conductance in each of K190C, R248C, R303C, K370C, and R1048C, an effect that may potentially be masked by inhibitory effects on channel open probability in normally gating channels. Login to comment
132 Error bars represent the means afe; S.E. from three to five patches. Cytoplasmic Entrance to the CFTR Channel Pore JUNE 19, 2015ߦVOLUME 290ߦNUMBER 25 JOURNAL OF BIOLOGICAL CHEMISTRY 15859 rent amplitude in each of K190C, R248C, R303C, K370C, K1041C, and R1048C. Login to comment
141 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). Login to comment
142 Among channels showing MTSES-sensitive current amplitudes, the order following modification was K1041C b0e; R1048C b0e; K370C b0e; R248C b0e; R303C b0e; K190C (Fig. 6, B and C, and 7B). Login to comment
155 Single channel recording indicated directly that for each of K190C, R248C, R303C, K370C, K1041C, and R1048C Clafa; conductance was reduced relative to Cys-less (Figs. 6 and 7A), Clafa; conductance was further reduced by modification by negatively charged MTSES (Figs. 6 and 7B), and Clafa; conductance was restored to near wild-type (Cys-less) values by modification by positively charged MTSET (Figs. 6 and 7C). Login to comment
166 In contrast, the effects of MTS modification of PPi-treated channels in K190C, R248C, R303C, K370C, and R1048C (Fig. 5) closely mirrored the charge-dependent effects of MTS modification on single channel current amplitude (Figs. 6 and 7). Login to comment
180 Error bars represent the means afe; S.E. from 3-10 patches. Cytoplasmic Entrance to the CFTR Channel Pore 15862 JOURNAL OF BIOLOGICAL CHEMISTRY VOLUME 290ߦNUMBER 25ߦJUNE 19, 2015 at SEMMELWEIS UNIV OF MEDICINE on December , when compared with K1041C and R1048C (Figs. 6C and 7B). Login to comment
182 Modification by MTSES had a lesser effect on unitary current amplitude in K1041C (b03;59% of Cys-less) and R1048C (b03;38% of Cys-less) (Fig. 6, B and C, and 7B) perhaps because these positive charges are located further from the major Clafa; permeation pathway. Login to comment