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Two-dimensional crystallization and projection structure of KcsA potassium channel.
Potassium channels are integral membrane proteins that play a crucial role in regulating diverse cell functions in both electrically excitable and non-excitable cells. Molecular cloning has revealed a diverse family of genes that encode these proteins, and a variety of experimental strategies have defined functional domains. We have cloned, over-expressed and purified the KcsA potassium channel to homogeneity and reconstituted this channel protein with phospholipids to form two-dimensional crystals. The crystals belong to plane group p4 and have unit cell dimensions of a=b=48 A. A projection map at 6 A resolution has been obtained by electron crystallography. The map shows that the protein is a homotetramer, having a low-density region on the 4-fold axis that is the site of the ion conduction pathway. Each monomer contains density features that are consistent with the molecular model of a truncated form of KcsA recently determined by X-ray crystallography.
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Related Subject Headings
- Streptomyces
- Protein Conformation
- Potassium Channels
- Membrane Proteins
- Image Processing, Computer-Assisted
- Dimerization
- Crystallography, X-Ray
- Crystallization
- Biochemistry & Molecular Biology
- Bacterial Proteins
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![Journal cover image](https://secure.syndetics.com/index.aspx?isbn=/lc.gif&issn=0022-2836&client=dukeuniv)
Published In
DOI
ISSN
Publication Date
Volume
Issue
Start / End Page
Location
Related Subject Headings
- Streptomyces
- Protein Conformation
- Potassium Channels
- Membrane Proteins
- Image Processing, Computer-Assisted
- Dimerization
- Crystallography, X-Ray
- Crystallization
- Biochemistry & Molecular Biology
- Bacterial Proteins