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Molecular determinants of differential pore blocking of kidney CLC-K chloride channels.
- Source :
-
EMBO reports [EMBO Rep] 2004 Jun; Vol. 5 (6), pp. 584-9. Date of Electronic Publication: 2004 May 28. - Publication Year :
- 2004
-
Abstract
- The highly homologous Cl(-) channels CLC-Ka and CLC-Kb are important for water and salt conservation in the kidney and for the production of endolymph in the inner ear. Mutations in CLC-Kb lead to Bartter's syndrome and mutations in the small CLC-K subunit barttin lead to Bartter's syndrome and deafness. Here we show that CLC-Ka is blocked by the recently identified blocker 2-(p-chlorophenoxy)-3-phenylpropionic acid of the rat channel CLC-K1 with an apparent K(D) approximately 80 microM. We also found that DIDS (4,4'-diisothiocyanatostilbene-2,2'-disulphonic acid), a generic Cl(-) channel blocker, inhibits CLC-Ka (K(D) approximately 90 microM). Surprisingly, the highly homologous channel CLC-Kb is fivefold to sixfold less sensitive to both compounds. Guided by the crystal structure of bacterial CLC proteins, we identify two amino acids, N68/D68 and G72/E72, in CLC-Ka and CLC-Kb, respectively, that are responsible for the differential drug sensitivity. Both residues expose their side chains in the extracellular pore mouth, delineating the probable drug binding site. These novel CLC-K channel blockers are promising lead compounds for the development of new diuretic drugs.
- Subjects :
- 2-Methyl-4-chlorophenoxyacetic Acid chemistry
4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid chemistry
Amino Acid Motifs genetics
Anion Transport Proteins genetics
Binding Sites genetics
Chloride Channels genetics
Dose-Response Relationship, Drug
Humans
Membrane Proteins genetics
Patch-Clamp Techniques
Point Mutation
Protein Structure, Tertiary
2-Methyl-4-chlorophenoxyacetic Acid analogs & derivatives
2-Methyl-4-chlorophenoxyacetic Acid pharmacology
4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid pharmacology
Anion Transport Proteins antagonists & inhibitors
Anion Transport Proteins chemistry
Chloride Channels antagonists & inhibitors
Chloride Channels chemistry
Membrane Proteins antagonists & inhibitors
Membrane Proteins chemistry
Subjects
Details
- Language :
- English
- ISSN :
- 1469-221X
- Volume :
- 5
- Issue :
- 6
- Database :
- MEDLINE
- Journal :
- EMBO reports
- Publication Type :
- Academic Journal
- Accession number :
- 15167890
- Full Text :
- https://doi.org/10.1038/sj.embor.7400169