Crystal structure and molecular imaging of the Nav channel β3 subunit indicates a trimeric assembly.
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Authors
Namadurai, Sivakumar
Balasuriya, Dilshan
Rajappa, Rajit
Wiemhöfer, Martin
Klingauf, Jurgen
Edwardson, J Michael
Chirgadze, Dimitri Y
Jackson, Antony P
Publication Date
2014-04-11Journal Title
J Biol Chem
ISSN
0021-9258
Publisher
Elsevier BV
Volume
289
Issue
15
Pages
10797-10811
Language
eng
Type
Article
Physical Medium
Print-Electronic
Metadata
Show full item recordCitation
Namadurai, S., Balasuriya, D., Rajappa, R., Wiemhöfer, M., Stott, K., Klingauf, J., Edwardson, J. M., et al. (2014). Crystal structure and molecular imaging of the Nav channel β3 subunit indicates a trimeric assembly.. J Biol Chem, 289 (15), 10797-10811. https://doi.org/10.1074/jbc.M113.527994
Abstract
The vertebrate sodium (Nav) channel is composed of an ion-conducting α subunit and associated β subunits. Here, we report the crystal structure of the human β3 subunit immunoglobulin (Ig) domain, a functionally important component of Nav channels in neurons and cardiomyocytes. Surprisingly, we found that the β3 subunit Ig domain assembles as a trimer in the crystal asymmetric unit. Analytical ultracentrifugation confirmed the presence of Ig domain monomers, dimers, and trimers in free solution, and atomic force microscopy imaging also detected full-length β3 subunit monomers, dimers, and trimers. Mutation of a cysteine residue critical for maintaining the trimer interface destabilized both dimers and trimers. Using fluorescence photoactivated localization microscopy, we detected full-length β3 subunit trimers on the plasma membrane of transfected HEK293 cells. We further show that β3 subunits can bind to more than one site on the Nav 1.5 α subunit and induce the formation of α subunit oligomers, including trimers. Our results suggest a new and unexpected role for the β3 subunits in Nav channel cross-linking and provide new structural insights into some pathological Nav channel mutations.
Keywords
Analytical Ultracentrifugation, Atomic Force Microscopy, In Vivo Imaging, Photoactivated Localization Microscopy, Protein Trimerization, Sodium Channels, X-ray Crystallography, Amino Acid Sequence, Binding Sites, Cloning, Molecular, Crystallization, Crystallography, X-Ray, Dimerization, HEK293 Cells, Humans, Immunoglobulins, Microscopy, Atomic Force, Molecular Sequence Data, NAV1.5 Voltage-Gated Sodium Channel, Protein Conformation, Ultracentrifugation, Voltage-Gated Sodium Channel beta-3 Subunit
Sponsorship
Wellcome Trust (089125/Z/09/Z)
Identifiers
External DOI: https://doi.org/10.1074/jbc.M113.527994
This record's URL: https://www.repository.cam.ac.uk/handle/1810/280466
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