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| | {{STRUCTURE_2fed| PDB=2fed | SCENE= }} | | {{STRUCTURE_2fed| PDB=2fed | SCENE= }} |
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| - | '''Structure of the E203Q mutant of the Cl-/H+ exchanger CLC-ec1 from E.Coli'''
| + | ===Structure of the E203Q mutant of the Cl-/H+ exchanger CLC-ec1 from E.Coli=== |
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| - | ==Overview==
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| - | CLC-ec1 is a prokaryotic CLC-type Cl(-)/H+ exchange transporter. Little is known about the mechanism of H+ coupling to Cl-. A critical glutamate residue, E148, was previously shown to be required for Cl(-)/H+ exchange by mediating proton transfer between the protein and the extracellular solution. To test whether an analogous H+ acceptor exists near the intracellular side of the protein, we performed a mutagenesis scan of inward-facing carboxyl-bearing residues and identified E203 as the unique residue whose neutralization abolishes H+ coupling to Cl- transport. Glutamate at this position is strictly conserved in all known CLCs of the transporter subclass, while valine is always found here in CLC channels. The x-ray crystal structure of the E203Q mutant is similar to that of the wild-type protein. Cl- transport rate in E203Q is inhibited at neutral pH, and the double mutant, E148A/E203Q, shows maximal Cl- transport, independent of pH, as does the single mutant E148A. The results argue that substrate exchange by CLC-ec1 involves two separate but partially overlapping permeation pathways, one for Cl- and one for H+. These pathways are congruent from the protein's extracellular surface to E148, and they diverge beyond this point toward the intracellular side. This picture demands a transport mechanism fundamentally different from familiar alternating-access schemes.
| + | The line below this paragraph, {{ABSTRACT_PUBMED_16316975}}, adds the Publication Abstract to the page |
| | + | (as it appears on PubMed at http://www.pubmed.gov), where 16316975 is the PubMed ID number. |
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| | + | {{ABSTRACT_PUBMED_16316975}} |
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| | ==About this Structure== | | ==About this Structure== |
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| | [[Category: Clc-ec1]] | | [[Category: Clc-ec1]] |
| | [[Category: Clca_ecoli]] | | [[Category: Clca_ecoli]] |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May 4 03:47:54 2008'' | + | |
| | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 29 00:45:50 2008'' |
Revision as of 21:45, 28 July 2008
Template:STRUCTURE 2fed
Structure of the E203Q mutant of the Cl-/H+ exchanger CLC-ec1 from E.Coli
Template:ABSTRACT PUBMED 16316975
About this Structure
2FED is a Single protein structure of sequence from Escherichia coli and Homo sapiens. Full crystallographic information is available from OCA.
Reference
Separate ion pathways in a Cl-/H+ exchanger., Accardi A, Walden M, Nguitragool W, Jayaram H, Williams C, Miller C, J Gen Physiol. 2005 Dec;126(6):563-70. PMID:16316975
Page seeded by OCA on Tue Jul 29 00:45:50 2008
