Visualization of the domain structure of an L-type Ca2+ channel using electron cryo-microscopy
Publication Type
Journal Article
Year of Publication
2003
Refereed Designation
Refereed
Journal
J Mol Biol
Volume
332
Pagination
171-82
Date Published
Sep 5
ISSN
0022-2836 (Print)
Accession Number
12946355
Citation Key
71
Number
1
Keywords
"*Protein Structure, Quaternary", Animals, "Calcium Channels, L-Type/*chemistry/isolation &", Cryoelectron Microscopy/*methods, "Models, Molecular", Molecular Weight, Protein Subunits/chemistry, purification/ultrastructure, Rabbits, Ryanodine Receptor Cal
Abstract
The three-dimensional structure of the skeletal muscle voltage-gated L-type calcium channel (Ca(v)1.1; dihydropyridine receptor, DHPR) was determined using electron cryo-microscopy and single-particle averaging. The structure shows a single channel complex with an approximate total molecular mass of 550 kDa, corresponding to the five known subunits of the DHPR, and bound detergent and lipid. Features visible in our structure together with antibody labeling of the beta and alpha(2) subunits allowed us to assign locations for four of the five subunits within the structure. The most striking feature of the structure is the extra-cellular alpha(2) subunit that protrudes from the membrane domain in close proximity to the alpha(1) subunit. The cytosolic beta subunit is located close to the membrane and adjacent to subunits alpha(1), gamma and delta. Our structure correlates well with the functional and biochemical data available for this channel and suggests a three-dimensional model for the excitation-contraction coupling complex consisting of DHPR tetrads and the calcium release channel.
