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| [[Image:1f6g.gif|left|200px]] | | [[Image:1f6g.png|left|200px]] |
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| ==Overview==
| | {{ABSTRACT_11158168}} |
| The molecular architecture of the NH(2) and COOH termini of the prokaryotic potassium channel KcsA has been determined using site-directed spin-labeling methods and paramagnetic resonance EPR spectroscopy. Cysteine mutants were generated (residues 5-24 and 121-160) and spin labeled, and the X-band CW EPR spectra were obtained from liposome-reconstituted channels at room temperature. Data on probe mobility (DeltaHo(-1)), accessibility parameters (PiO(2) and PiNiEdda), and inter-subunit spin-spin interaction (Omega) were used as structural constraints to build a three-dimensional folding model of these cytoplasmic domains from a set of simulated annealing and restrained molecular dynamics runs. 32 backbone structures were generated and averaged using fourfold symmetry, and a final mean structure was obtained from the eight lowest energy runs. Based on the present data, together with information from the KcsA crystal structure, a model for the three-dimensional fold of full-length KcsA was constructed. In this model, the NH(2) terminus of KcsA forms an alpha-helix anchored at the membrane-water interface, while the COOH terminus forms a right-handed four-helix bundle that extend some 40-50 A towards the cytoplasm. Functional analysis of COOH-terminal deletion constructs suggest that, while the COOH terminus does not play a substantial role in determining ion permeation properties, it exerts a modulatory role in the pH-dependent gating mechanism.
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| ==About this Structure== | | ==About this Structure== |
| 1F6G is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Streptomyces_lividans Streptomyces lividans]. The following page contains interesting information on the relation of 1F6G with [[http://pdb.rcsb.org/pdb/static.do?p=education_discussion/molecule_of_the_month/pdb38_1.html Potassium Channels]]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1F6G OCA]. | | 1F6G is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Streptomyces_lividans Streptomyces lividans]. The following page contains interesting information on the relation of 1F6G with [[http://pdb.rcsb.org/pdb/static.do?p=education_discussion/molecule_of_the_month/pdb38_1.html Potassium Channels]]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1F6G OCA]. |
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| ==Reference==
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| Molecular architecture of full-length KcsA: role of cytoplasmic domains in ion permeation and activation gating., Cortes DM, Cuello LG, Perozo E, J Gen Physiol. 2001 Feb;117(2):165-80. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/11158168 11158168]
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| [[Category: Potassium Channels]] | | [[Category: Potassium Channels]] |
| [[Category: Single protein]] | | [[Category: Single protein]] |
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| [[Category: Integral membrane protein]] | | [[Category: Integral membrane protein]] |
| [[Category: Potassium channel]] | | [[Category: Potassium channel]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 15:57:36 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Jun 26 17:15:23 2008'' |