2hg5

Cs+ complex of a K channel with an amide to ester substitution in the selectivity filter

spinqualitylabelsall models 2hg5, resolution 2.75Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2hg5 is a 4 chain structure with sequence from Lk3 transgenic mice. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: B3H, CS, GOA Related: 2h8p, 2hfe Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [KCSA_STRLI] Acts as a pH-gated potassium ion channel; changing the cytosolic pH from 7 to 4 opens the channel, although it is not clear if this is the physiological stimulus for channel opening. Monovalent cation preference is K(+) > Rb(+) > NH4(+) >> Na(+) > Li(+). Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed The selectivity filter of K(+) channels comprises four contiguous ion binding sites, S1 through S4. Structural and functional data indicate that the filter contains on average two K(+) ions at any given time and that these ions reside primarily in two configurations, namely to sites S1 and S3 or to sites S2 and S4. Maximum ion flux through the channel is expected to occur when the energy difference between these two binding configurations is zero. In this study, we have used protein semisynthesis to selectively perturb site 1 within the filter of the KcsA channel through use of an amide-to-ester substitution. The modification alters K(+) conduction properties. The structure of the selectivity filter is largely unperturbed by the modification, despite the loss of an ordered water molecule normally located just behind the filter. Introduction of the ester moiety was found to alter the distribution of K(+), Rb(+,) and Cs(+) within the filter, with the most dramatic change found for Rb(+). The redistribution of ions is associated with the appearance of a partially hydrated ion just external to the filter, at a position where no ion is observed in the wild-type channel. The appearance of this new ion-binding site creates a change in the distance between a pair of K(+) ions some fraction of the time, apparently leading to a reduction in the ion conduction rate. Importantly, this finding suggests that the selectivity filter of a potassium channel is optimized both in terms of absolute ion occupancy and in terms of the separation in distance between the conducting ions. Structural and functional consequences of an amide-to-ester substitution in the selectivity filter of a potassium channel.,Valiyaveetil FI, Sekedat M, MacKinnon R, Muir TW J Am Chem Soc. 2006 Sep 6;128(35):11591-9. PMID:16939283 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Monoclonal Antibodies 3D structures Potassium Channel

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