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Electron Crystallography of a Prokaryotic Potassium Channel

Published online by Cambridge University Press:  02 July 2020

H.X. Sui
Affiliation:
Life Sciences Division, Lawrence Berkeley National Laboratory, University of California, Berkeley, CA, 94720
H.L. Li
Affiliation:
Life Sciences Division, Lawrence Berkeley National Laboratory, University of California, Berkeley, CA, 94720
S. Ghanshani
Affiliation:
Department of Physiology and Biophysics, and Medicine, University of California, Irvine, CA, 92697
S. Lee
Affiliation:
Life Sciences Division, Lawrence Berkeley National Laboratory, University of California, Berkeley, CA, 94720
P.J. Walian
Affiliation:
Life Sciences Division, Lawrence Berkeley National Laboratory, University of California, Berkeley, CA, 94720
C.L. Wu
Affiliation:
Department of Physiology and Biophysics, and Medicine, University of California, Irvine, CA, 92697
K.G. Chandy
Affiliation:
Department of Physiology and Biophysics, and Medicine, University of California, Irvine, CA, 92697
B.K. Jap
Affiliation:
Life Sciences Division, Lawrence Berkeley National Laboratory, University of California, Berkeley, CA, 94720
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Extract

Potassium channels are ubiquitous ion channel proteins which play a crucial role in a broad spectrum of important cell functions. KcsA is a potassium channel found in the bacterium, Streptomyces lividan, and is believed to have only two transmembrane helices.

The KcsA protein has been cloned, overexpressed and purified to homogeneity, and reconstituted with phospholipids to form two-dimensional (2-D) crystals. Crystal samples were embedded in trehalose and examined in a cryo-holder (-170 °C) using a JEOL 4000EX electron microscope operated at 400kV in low dose mode. Images were recorded in spot scan-mode at a magnification of 60,000X, then digitized on a Perkin Elmer PDS flat bed microdensitometer and processed by using the MRC program suite. Processed images were brought to a common phase origin, and the amplitudes and phases from individual images were vectorially combined.

Type
High Resolution Protein Structures from Electron Crystallography
Copyright
Copyright © Microscopy Society of America

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References

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