ABCC7 p.Lys95Arg
| 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 common inhibitor binding site in the... J Biol Chem. 2005 Mar 11;280(10):8945-50. Epub 2005 Jan 5. Linsdell P
Location of a common inhibitor binding site in the cytoplasmic vestibule of the cystic fibrosis transmembrane conductance regulator chloride channel pore.
J Biol Chem. 2005 Mar 11;280(10):8945-50. Epub 2005 Jan 5., 2005-03-11 [PMID:15634668]
Abstract [show]
Chloride transport by the cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channel is inhibited by a broad range of organic anions that enter the channel pore from its cytoplasmic end, physically occluding the Cl- permeation pathway. These open channel blocker molecules are presumed to bind within a relatively wide pore inner vestibule that shows little discrimination between different large anions. The present study uses patch clamp recording to identify a pore-lining lysine residue, Lys-95, that acts to attract large blocker molecules into this inner vestibule. Mutations that remove the fixed positive charge associated with this amino acid residue dramatically weaken the blocking effects of five structurally unrelated open channel blockers (glibenclamide, 4,4'-dinitrostilbene-2,2'-disulfonic acid, lonidamine, 5-nitro-2-(3-phenylpropylamino)benzoic acid, and taurolithocholate-3-sulfate) when applied to the cytoplasmic face of the membrane. Mutagenesis of Lys-95 also induced amino acid side chain charge-dependent rectification of the macroscopic current-voltage relationship, consistent with the fixed positive charge on this residue normally acting to attract Cl- ions from the intracellular solution into the pore. These results identify Lys-95 as playing an important role in attracting permeant anions into the channel pore inner vestibule, probably by an electrostatic mechanism. This same electrostatic attraction mechanism also acts to attract larger anionic molecules into the relatively wide inner vestibule, where these substances bind to block Cl- permeation. Thus, structurally diverse open channel blockers of CFTR appear to share a common molecular mechanism of action that involves interaction with a positively charged amino acid side chain located in the inner vestibule of the pore.
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No. Sentence Comment
69 In a striking parallel with previous findings involving Arg-334 (13, 16), mutagenesis of Lys-95 had a strongly charge-dependent effect on I-V rectification (Fig. 1); the charge-conservative K95R, like wild type CFTR, showed a practically linear I-V relationship, whereas all of the other mutations, and especially the charge-reversing K95E, caused significant outward rectification.
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ABCC7 p.Lys95Arg 15634668:69:190
status: NEW91 These results, using a number of different amino acid substitutions of Lys-95, strongly suggest that side chain charge at this position is important in controlling the apparent affinity of glibenclamide block; the apparent Kd at -100 mV was not affected in the charge-conservative K95R but was significantly increased in charge-neutralizing mutants (K95A, K95C, K95Q) and most strongly increased in the charge-reversing K95E mutant.
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ABCC7 p.Lys95Arg 15634668:91:281
status: NEW[hide] Molecular mechanism of arachidonic acid inhibition... Eur J Pharmacol. 2007 Jun 1;563(1-3):88-91. Epub 2007 Mar 3. Zhou JJ, Linsdell P
Molecular mechanism of arachidonic acid inhibition of the CFTR chloride channel.
Eur J Pharmacol. 2007 Jun 1;563(1-3):88-91. Epub 2007 Mar 3., [PMID:17397825]
Abstract [show]
Arachidonic acid inhibits the activity of a number of different Cl- channels, however its molecular mechanism of action is not known. Here we show that inhibition of cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channels by arachidonic acid is weakened following mutagenesis of two positively charged pore-lining amino acids. Charge-neutralizing mutants K95Q and R303Q both increased the Kd for inhibition from approximately 3.5 microM in wild type to approximately 17 microM. At both sites, the effects of mutagenesis were dependent of the charge of the substituted side chain. We suggest that arachidonic acid interacts electrostatically with positively charged amino acid side chains in the cytoplasmic vestibule of the CFTR channel pore to block Cl- permeation.
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No. Sentence Comment
38 Thus, while the charge conservative K95R and R303K mutations were not associated with a significant increase in Kd (PN0.3, two-tailed t-test) all mutations which neutralized or reversed either of these two positive charges were associated with a significant increase in Kd (Fig. 2).
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ABCC7 p.Lys95Arg 17397825:38:36
status: NEW