Document Detail


Distinct functional stoichiometry of potassium channel beta subunits.
MedLine Citation:
PMID:  9465105     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Shaker-type potassium channels play important roles in determining the electrical excitability of cells. The native channel complex is thought to be formed by four pore-forming alpha subunits that provide four interaction sites for auxiliary modulatory Kvbeta subunits. Because Kvbeta subunits possess diverse modulatory activities including either up-regulation or down-regulation of potassium currents, differential assembly of the alpha-beta complex could give rise to diverse current properties. However, the detailed physical and functional stoichiometry of the alpha-beta complex remains unknown. Kvbeta1 subunits reduce potassium currents through inactivation, whereas Kvbeta2 subunits enhance potassium currents by inhibiting the Kvbeta1-mediated inactivation and at the same time by promoting the surface expression of certain potassium channels. In this report we show that Kvbeta1 and Kvbeta2 of the Shaker-type potassium channels display distinct functional stoichiometry to interact with the Kv1 alpha subunits, a subfamily of Shaker-type potassium channels. The interaction of Kvbeta1 subunits with alpha subunits is consistent with the alpha4betan model, where n equals 0, 1, 2, 3, or 4, depending upon the relative concentration of alpha and beta subunits. The alpha4betan stoichiometry allows for gradual changes of the Kvbeta1-mediated inactivation. In contrast, Kvbeta2 subunits self-associate to form oligomers and interact with the alpha subunits via alpha4beta4 stoichiometry, which permits effective multivalent associations with alpha subunits. Such distinct functional stoichiometry of Kvbeta1 and Kvbeta2 provides a molecular mechanism that is well suited to their contrasting activities of up-regulation or down-regulation of potassium currents.
Authors:
J Xu; W Yu; J M Wright; R W Raab; M Li
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Proceedings of the National Academy of Sciences of the United States of America     Volume:  95     ISSN:  0027-8424     ISO Abbreviation:  Proc. Natl. Acad. Sci. U.S.A.     Publication Date:  1998 Feb 
Date Detail:
Created Date:  1998-03-19     Completed Date:  1998-03-19     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  7505876     Medline TA:  Proc Natl Acad Sci U S A     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1846-51     Citation Subset:  IM    
Affiliation:
Department of Physiology, The Johns Hopkins University School of Medicine, 725 North Wolfe Street, Baltimore, MD 21205, USA.
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MeSH Terms
Descriptor/Qualifier:
Animals
COS Cells
Dimerization
Macromolecular Substances
Patch-Clamp Techniques
Potassium Channels / chemistry*,  metabolism
Protein Binding
Sequence Deletion
Shaker Superfamily of Potassium Channels
Structure-Activity Relationship
Chemical
Reg. No./Substance:
0/Macromolecular Substances; 0/Potassium Channels; 0/Shaker Superfamily of Potassium Channels
Comments/Corrections

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