ABCC7 p.Lys95His
| Predicted by SNAP2: | A: D (75%), C: D (75%), D: D (91%), E: D (85%), F: D (85%), G: D (85%), H: D (53%), I: D (80%), L: D (80%), M: D (75%), N: D (80%), P: D (91%), Q: D (75%), R: N (66%), S: D (63%), T: D (80%), V: D (80%), W: D (91%), Y: D (71%), |
| Predicted by PROVEAN: | A: N, C: D, D: N, E: N, F: D, G: D, H: N, I: D, L: D, M: N, N: N, P: N, Q: N, R: N, S: N, T: N, V: N, W: D, Y: D, |
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[hide] Location of a permeant anion binding site in the c... J Physiol Sci. 2015 May;65(3):233-41. doi: 10.1007/s12576-015-0359-6. Epub 2015 Feb 12. Rubaiy HN, Linsdell P
Location of a permeant anion binding site in the cystic fibrosis transmembrane conductance regulator chloride channel pore.
J Physiol Sci. 2015 May;65(3):233-41. doi: 10.1007/s12576-015-0359-6. Epub 2015 Feb 12., [PMID:25673337]
Abstract [show]
In the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel, lyotropic anions with high permeability also bind relatively tightly within the pore. However, the location of permeant anion binding sites, as well as their relationship to anion permeability, is not known. We have identified lysine residue K95 as a key determinant of permeant anion binding in the CFTR pore. Lyotropic anion binding affinity is related to the number of positively charged amino acids located in the inner vestibule of the pore. However, mutations that change the number of positive charges in this pore region have minimal effects on anion permeability. In contrast, a mutation at the narrow pore region alters permeability with minimal effects on anion binding. Our results suggest that a localized permeant anion binding site exists in the pore; however, anion binding to this site has little influence over anion permeability. Implications of this work for the mechanisms of anion recognition and permeability in CFTR are discussed.
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No. Sentence Comment
73 a Example macroscopic I-V relationships for K95H/E1371Q CFTR channels recorded using bath solutions at pH 5.5 (left) or pH 9.0 (right, different patch).
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ABCC7 p.Lys95His 25673337:73:44
status: NEW75 b Mean KD values for Au(CN)2 - block of K95H/E1371Q at these two different pHs, obtained as described for Au(CN)2 - in Fig. 1.
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ABCC7 p.Lys95His 25673337:75:40
status: NEW77 c Relationship between the observed KD values for Au(CN)2 - block (at -100 mV) and bath solution pH in K95H/ E1371Q and E1371Q.
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ABCC7 p.Lys95His 25673337:77:103
status: NEW80 K95H0 refers to the unprotonated form of the histidine side chain (as expected at pH 9.0) and K95H?
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ABCC7 p.Lys95His 25673337:80:94
status: NEW86 As shown in Fig. 3a and b, block of K95H/E1371Q by intracellular Au(CN)2 - was drastically stronger at pH 5.5 compared to pH 9.0, with the mean KD at -100 mV being increased 244-fold at the more alkaline pH.
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ABCC7 p.Lys95His 25673337:86:36
status: NEW112 Removal of a positive charge in the pore inner vestibule by mutagenesis (in the K95Q mutant) or by increasing pH (in K95H) dramatically increases the apparent KD (Figs. 1, 2, 3, 4), suggesting that this positive charge is required for tight binding of permeant anions.
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ABCC7 p.Lys95His 25673337:112:117
status: NEW113 In fact, since Au(CN)2 - , SCN- and C(CN)3 - are permeant anions and presumably have access to the entire pore, it is possible that the residual block observed in K95Q and in K95H (at pH 9.0) reflects interactions with a different part of the pore.
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ABCC7 p.Lys95His 25673337:113:175
status: NEW