Document Detail


Asymmetric arrangement of auxiliary subunits of skeletal muscle voltage-gated l-type Ca(2+) channel.
MedLine Citation:
PMID:  11264005     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Highly purified L-type Ca(2+) channel complexes containing all five subunits (alpha(1), alpha(2), beta, gamma, and delta) and complexes of alpha(1)-beta subunits were obtained from skeletal muscle triad membranes by three-step purification and by 1% Triton X-100 treatment, respectively. Their structures and the subunit arrangements were analyzed by electron microscopy. Projection images of negatively stained Ca(2+) channels and alpha(1)-beta complexes were aligned, classified and averaged. The alpha(1)-beta complex showed a hollow trapezoid shape of 12 nm height. In top view, four asymmetric domains surrounded a central depression predicted to form the channel pore. The complete Ca(2+) channel complex exhibited the cylindrical shape of 20 nm in height binding a spherical domain on one edge. Further image analysis of higher complexes of the Ca(2+) channel using a monoclonal antibody against the beta subunit showed that the alpha(1)-beta complex forms the non-decorated side of the cylinder, which can traverse the membrane from outside the cell to the cytoplasm. Based on these results, we propose that the Ca(2+) channel exhibits an asymmetric arrangement of auxiliary subunits.
Authors:
K Murata; N Odahara; A Kuniyasu; Y Sato; H Nakayama; K Nagayama
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Biochemical and biophysical research communications     Volume:  282     ISSN:  0006-291X     ISO Abbreviation:  Biochem. Biophys. Res. Commun.     Publication Date:  2001 Mar 
Date Detail:
Created Date:  2001-03-26     Completed Date:  2001-04-12     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0372516     Medline TA:  Biochem Biophys Res Commun     Country:  United States    
Other Details:
Languages:  eng     Pagination:  284-91     Citation Subset:  IM    
Copyright Information:
Copyright 2001 Academic Press.
Affiliation:
National Institute for Physiological Sciences, Myodaiji, Okazaki, 444-8585, Japan.
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MeSH Terms
Descriptor/Qualifier:
Animals
Calcium Channels, L-Type / chemistry,  metabolism*
Electrophoresis, Polyacrylamide Gel
Microscopy, Electron
Muscle, Skeletal / metabolism*,  ultrastructure
Protein Conformation
Rabbits
Chemical
Reg. No./Substance:
0/Calcium Channels, L-Type

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