The appearance of detergent-solubilized voltage-regulated sodium channel protein was recently characterized by this laboratory. Negative-staining revealed rod-shaped particles measuring 40 X 170 A. Further studies have suggested that the actual configuration of this protein may be quite different from the rod-shaped structures. Freeze-fracture and freeze-etch images of the protein in reconstituted membranes indicated that the channel is cylindrical with a diameter of 100 A and a minimum length of 80 A. Experiments with two detergent systems (Lubrol-PX and sodium cholate) enabled us to explain the discrepancy between this structure and the rod-shaped particles visualized earlier. Negative staining in either detergent at low pH (4.5) produced rod-shaped structures. As the pH was increased, doughnut-shaped particles, consistent with the structure of the protein in freeze-etch, appeared in negative stain. The tendency of the protein to change shape under different pH conditions appears to be a peculiar property of this protein.
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http://dx.doi.org/10.1083/jcb.97.6.1834 | DOI Listing |
Front Immunol
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Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, An-Najah National University, Nablus, Palestine.
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January 2025
Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA.
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Institute for Neurophysiology, Uniklinik RWTH Aachen University, Aachen, Germany.
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View Article and Find Full Text PDFInt J Biol Macromol
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College of Chemistry, Fuzhou University, Fuzhou 350116, China.
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