Subunit Structure of Dihydropyridine-Sensitive Calcium Channels from Skeletal Muscle

Purified dihydropyridine-sensitive calcium channels from rabbit transverse-tubule membranes consist of three noncovalently associated classes of subunits: α (167 kDa), β (54 kDa), and γ (30 kDa). Cleavage of disulfide bonds reveals two distinct α polypeptides and an additional component, δ . The α 1...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 1987-08, Vol.84 (15), p.5478-5482
Main Authors: Takahashi, Masami, Seagar, Michael J., Jones, Jean F., Bernhard F. X. Reber, Catterall, William A.
Format: Article
Language:English
Subjects:
Animals
Antibodies
Biological and medical sciences
Calcium
Calcium - metabolism
Calcium Channel Blockers - pharmacology
Calcium channels
Cell physiology
Detergents
dihydropyridine
Disulfides
Electrophoresis, Polyacrylamide Gel
Fundamental and applied biological sciences. Psychology
Gels
Ion Channels - ultrastructure
Lectins
Lentils
Macromolecular Substances
Molecular and cellular biology
Muscles - analysis
Neurotransmission
Peptides - analysis
Phosphorylation
Protein Conformation
Rabbits
Skeletal muscle
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Summary:Purified dihydropyridine-sensitive calcium channels from rabbit transverse-tubule membranes consist of three noncovalently associated classes of subunits: α (167 kDa), β (54 kDa), and γ (30 kDa). Cleavage of disulfide bonds reveals two distinct α polypeptides and an additional component, δ . The α 1 subunit, a 175-kDa polypeptide that is not N-glycosylated, contains the dihydropyridine binding site, cAMP-dependent protein kinase phosphorylation site(s), and substantial hydrophobic domain(s). α 2, a 143-kDa glycoprotein, has none of the properties characteristic of α 1 but binds lectins and contains about 25% N-linked carbohydrate. α 2 is disulfide-linked to δ , a 24- to 27-kDa glycopeptide. β (54 kDa) contains a cAMP-dependent phosphorylation site but is not N-glycosylated and does not have a hydrophobic domain. γ (30 kDa) has a carbohydrate content of about 30% and extensive hydrophobic domain(s). Precipitation with affinity-purified anti-α 1 antibodies or α 2-specific lentil lectin-agarose demonstrated that α 1α 2β γ δ behaves as a complex in the presence of digitonin or 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate, whereas the α 2δ complex dissociates from α 1β γ in the presence of Triton X-100. A model for subunit interaction and membrane insertion is proposed on the basis of these observations.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.84.15.5478