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Biophys J
2008 Nov 15;9510:4668-75. doi: 10.1529/biophysj.108.137158.
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Insights into the ClC-4 transport mechanism from studies of Zn2+ inhibition.
Osteen JD
,
Mindell JA
.
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The CLC family of chloride channels and transporters is a functionally diverse group of proteins important in a wide range of physiological processes. ClC-4 and ClC-5 are localized to endosomes and seem to play roles in the acidification of these compartments. These proteins were recently shown to function as Cl(-)/H(+) antiporters. However, relatively little is known about the detailed mechanism of CLC-mediated Cl(-)/H(+) antiport, especially for mammalian isoforms. We attempted to identify molecular tools that might be useful in probing structure-function relationships in these proteins. Here, we record currents from human ClC-4 (hClC-4) expressed in Xenopus oocytes, and find that Zn(2+) inhibits these currents, with an apparent affinity of approximately 50 microM. Although Cd(2+) has a similar effect, Co(2+) and Mn(2+) do not inhibit hClC-4 currents. In contrast, the effect of Zn(2+) on the ClC-0 channel, Zn(2+)-mediated inhibition of hClC-4 is minimally voltage-dependent, suggesting an extracellular binding site for the ion. Nine candidate external residues were tested; only mutations of three consecutive histidine residues, located in a single extracellular loop, significantly reduced the effect of Zn(2+), with one of these making a larger contribution than the other two. An analogous tri-His sequence is absent from ClC-0, suggesting a fundamentally different inhibitory mechanism for the ion on hClC-4. Manipulations that alter transport properties of hClC-4, varying permeant ions as well as mutating the "gating glutamate", dramatically affect Zn(2+) inhibition, suggesting the involvement of a heretofore unexplored part of the protein in the transport process.
Accardi,
Secondary active transport mediated by a prokaryotic homologue of ClC Cl- channels.
2004, Pubmed
Accardi,
Secondary active transport mediated by a prokaryotic homologue of ClC Cl- channels.
2004,
Pubmed
Beyersmann,
Functions of zinc in signaling, proliferation and differentiation of mammalian cells.
2001,
Pubmed
Chen,
Extracellular zinc ion inhibits ClC-0 chloride channels by facilitating slow gating.
1998,
Pubmed
,
Xenbase
Clark,
Characterization of the hyperpolarization-activated chloride current in dissociated rat sympathetic neurons.
1998,
Pubmed
,
Xenbase
Dutzler,
Gating the selectivity filter in ClC chloride channels.
2003,
Pubmed
,
Xenbase
Dutzler,
The structural basis of ClC chloride channel function.
2004,
Pubmed
Dutzler,
X-ray structure of a ClC chloride channel at 3.0 A reveals the molecular basis of anion selectivity.
2002,
Pubmed
Eide,
Zinc transporters and the cellular trafficking of zinc.
2006,
Pubmed
Engh,
Cysteine accessibility in ClC-0 supports conservation of the ClC intracellular vestibule.
2005,
Pubmed
,
Xenbase
Estévez,
Conservation of chloride channel structure revealed by an inhibitor binding site in ClC-1.
2003,
Pubmed
,
Xenbase
Friedrich,
Mutational analysis demonstrates that ClC-4 and ClC-5 directly mediate plasma membrane currents.
1999,
Pubmed
,
Xenbase
Graves,
The Cl-/H+ antiporter ClC-7 is the primary chloride permeation pathway in lysosomes.
2008,
Pubmed
Günther,
ClC-5, the chloride channel mutated in Dent's disease, colocalizes with the proton pump in endocytotically active kidney cells.
1998,
Pubmed
Hebeisen,
Anion permeation in human ClC-4 channels.
2003,
Pubmed
Kürz,
Probing the major skeletal muscle chloride channel with Zn2+ and other sulfhydryl-reactive compounds.
1997,
Pubmed
,
Xenbase
Lin,
Elimination of the slow gating of ClC-0 chloride channel by a point mutation.
1999,
Pubmed
,
Xenbase
Lloyd,
A common molecular basis for three inherited kidney stone diseases.
1996,
Pubmed
,
Xenbase
Mohammad-Panah,
The chloride channel ClC-4 contributes to endosomal acidification and trafficking.
2003,
Pubmed
Nguitragool,
CLC Cl /H+ transporters constrained by covalent cross-linking.
2007,
Pubmed
Palmiter,
ZnT-2, a mammalian protein that confers resistance to zinc by facilitating vesicular sequestration.
1996,
Pubmed
Picollo,
Chloride/proton antiporter activity of mammalian CLC proteins ClC-4 and ClC-5.
2005,
Pubmed
Piwon,
ClC-5 Cl- -channel disruption impairs endocytosis in a mouse model for Dent's disease.
2000,
Pubmed
Reyes,
Novel outwardly rectifying anion conductance in Xenopus oocytes.
2004,
Pubmed
,
Xenbase
Scheel,
Voltage-dependent electrogenic chloride/proton exchange by endosomal CLC proteins.
2005,
Pubmed
,
Xenbase
Vanoye,
Functional characterization of recombinant human ClC-4 chloride channels in cultured mammalian cells.
2002,
Pubmed
Wang,
CLC-3 channels modulate excitatory synaptic transmission in hippocampal neurons.
2006,
Pubmed
Zdebik,
Determinants of anion-proton coupling in mammalian endosomal CLC proteins.
2008,
Pubmed