2htk
From Proteopedia
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|PDB= 2htk |SIZE=350|CAPTION= <scene name='initialview01'>2htk</scene>, resolution 3.41Å | |PDB= 2htk |SIZE=350|CAPTION= <scene name='initialview01'>2htk</scene>, resolution 3.41Å | ||
|SITE= | |SITE= | ||
| - | |LIGAND= <scene name='pdbligand=BR:BROMIDE ION'>BR</scene> | + | |LIGAND= <scene name='pdbligand=BR:BROMIDE+ION'>BR</scene> |
|ACTIVITY= | |ACTIVITY= | ||
|GENE= clcA, eriC ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=562 Escherichia coli]) | |GENE= clcA, eriC ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=562 Escherichia coli]) | ||
| + | |DOMAIN= | ||
| + | |RELATEDENTRY=[[1ots|1OTS]], [[2ht2|2HT2]], [[2ht3|2HT3]], [[2ht4|2HT4]], [[2htl|2HTL]], [[2hlf|2HLF]] | ||
| + | |RESOURCES=<span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=2htk FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2htk OCA], [http://www.ebi.ac.uk/pdbsum/2htk PDBsum], [http://www.rcsb.org/pdb/explore.do?structureId=2htk RCSB]</span> | ||
}} | }} | ||
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[[Category: Miller, C.]] | [[Category: Miller, C.]] | ||
[[Category: Williams, C.]] | [[Category: Williams, C.]] | ||
| - | [[Category: BR]] | ||
[[Category: clc family of channel and transporter]] | [[Category: clc family of channel and transporter]] | ||
[[Category: fab complex]] | [[Category: fab complex]] | ||
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[[Category: membrane protein]] | [[Category: membrane protein]] | ||
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Mar 31 03:35:13 2008'' |
Revision as of 00:35, 31 March 2008
| |||||||
| , resolution 3.41Å | |||||||
|---|---|---|---|---|---|---|---|
| Ligands: | |||||||
| Gene: | clcA, eriC (Escherichia coli) | ||||||
| Related: | 1OTS, 2HT2, 2HT3, 2HT4, 2HTL, 2HLF
| ||||||
| Resources: | FirstGlance, OCA, PDBsum, RCSB | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
Structure of the Escherichia coli ClC chloride channel Y445A mutant and Fab complex
Overview
The Cl-/H+ exchange-transporter CLC-ec1 mediates stoichiometric transmembrane exchange of two Cl- ions for one proton. A conserved tyrosine residue, Y445, coordinates one of the bound Cl- ions visible in the structure of this protein and is located near the intersection of the Cl- and H+ pathways. Mutants of this tyrosine were scrutinized for effects on the coupled transport of Cl- and H+ determined electrophysiologically and on protein structure determined crystallographically. Despite the strong conservation of Y445 in the CLC family, substitution of F or W at this position preserves wild-type transport behavior. Substitution by A, E, or H, however, produces uncoupled proteins with robust Cl- transport but greatly impaired movement of H+. The obligatory 2 Cl-/1 H+ stoichiometry is thus lost in these mutants. The structures of all the mutants are essentially identical to wild-type, but apparent anion occupancy in the Cl- binding region correlates with functional H+ coupling. In particular, as determined by anomalous diffraction in crystals grown in Br-, an electrophysiologically competent Cl- analogue, the well-coupled transporters show strong Br- electron density at the "inner" and "central" Cl- binding sites. However, in the uncoupled mutants, Br- density is absent at the central site, while still present at the inner site. An additional mutant, Y445L, is intermediate in both functional and structural features. This mutant clearly exchanges H+ for Cl-, but at a reduced H+-to-Cl- ratio; likewise, both the central and inner sites are occupied by Br-, but the central site shows lower Br- density than in wild-type (or in Y445F,W). The correlation between proton coupling and central-site occupancy argues that halide binding to the central transport site somehow facilitates movement of H+, a synergism that is not readily understood in terms of alternating-site antiport schemes.
About this Structure
2HTK is a Single protein structure of sequence from Escherichia coli and Mus musculus. Full crystallographic information is available from OCA.
Reference
Synergism between halide binding and proton transport in a CLC-type exchanger., Accardi A, Lobet S, Williams C, Miller C, Dutzler R, J Mol Biol. 2006 Sep 29;362(4):691-9. Epub 2006 Aug 2. PMID:16949616
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