2q6a
From Proteopedia
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|PDB= 2q6a |SIZE=350|CAPTION= <scene name='initialview01'>2q6a</scene>, resolution 2.600Å | |PDB= 2q6a |SIZE=350|CAPTION= <scene name='initialview01'>2q6a</scene>, resolution 2.600Å | ||
|SITE= | |SITE= | ||
| - | |LIGAND= <scene name='pdbligand=CA:CALCIUM+ION'>CA</scene> | + | |LIGAND= <scene name='pdbligand=CA:CALCIUM+ION'>CA</scene>, <scene name='pdbligand=NA:SODIUM+ION'>NA</scene> |
|ACTIVITY= | |ACTIVITY= | ||
|GENE= | |GENE= | ||
| + | |DOMAIN= | ||
| + | |RELATEDENTRY=[[2ahy|2AHY]], [[2ahz|2AHZ]] | ||
| + | |RESOURCES=<span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=2q6a FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2q6a OCA], [http://www.ebi.ac.uk/pdbsum/2q6a PDBsum], [http://www.rcsb.org/pdb/explore.do?structureId=2q6a RCSB]</span> | ||
}} | }} | ||
| Line 25: | Line 28: | ||
[[Category: Jiang, Y.]] | [[Category: Jiang, Y.]] | ||
[[Category: Shi, N.]] | [[Category: Shi, N.]] | ||
| - | [[Category: CA]] | ||
| - | [[Category: NA]] | ||
[[Category: central cavity]] | [[Category: central cavity]] | ||
[[Category: helix bundle]] | [[Category: helix bundle]] | ||
| Line 35: | Line 36: | ||
[[Category: tetramer]] | [[Category: tetramer]] | ||
| - | ''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 04:45:21 2008'' |
Revision as of 01:45, 31 March 2008
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| , resolution 2.600Å | |||||||
|---|---|---|---|---|---|---|---|
| Ligands: | , | ||||||
| Related: | 2AHY, 2AHZ
| ||||||
| Resources: | FirstGlance, OCA, PDBsum, RCSB | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
Crystal Structure of Nak channel D66E mutant
Overview
Apparent blockage of monovalent cation currents by the permeating blocker Ca(2+) is a physiologically essential phenomenon relevant to cyclic nucleotide-gated (CNG) channels. The recently determined crystal structure of a bacterial homolog of CNG channel pores, the NaK channel, revealed a Ca(2+) binding site at the extracellular entrance to the selectivity filter. This site is not formed by the side-chain carboxylate groups from the conserved acidic residue, Asp-66 in NaK, conventionally thought to directly chelate Ca(2+) in CNG channels, but rather by the backbone carbonyl groups of residue Gly-67. Here we present a detailed structural analysis of the NaK channel with a focus on Ca(2+) permeability and blockage. Our results confirm that the Asp-66 residue, although not involved in direct chelation of Ca(2+), plays an essential role in external Ca(2+) binding. Furthermore, we give evidence for the presence of a second Ca(2+) binding site within the NaK selectivity filter where monovalent cations also bind, providing a structural basis for Ca(2+) permeation through the NaK pore. Compared with other Ca(2+)-binding proteins, both sites in NaK present a novel mode of Ca(2+) chelation, using only backbone carbonyl oxygen atoms from residues in the selectivity filter. The external site is under indirect control by an acidic residue (Asp-66), making it Ca(2+)-specific. These findings give us a glimpse of the possible underlying mechanisms allowing Ca(2+) to act both as a permeating ion and blocker of CNG channels and raise the possibility of a similar chemistry governing Ca(2+) chelation in Ca(2+) channels.
About this Structure
2Q6A is a Single protein structure of sequence from Bacillus cereus. Full crystallographic information is available from OCA.
Reference
Structural insight into Ca2+ specificity in tetrameric cation channels., Alam A, Shi N, Jiang Y, Proc Natl Acad Sci U S A. 2007 Sep 25;104(39):15334-9. Epub 2007 Sep 18. PMID:17878296
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