(Journal Article): Acceleration of activation and inactivation by the beta subunit of the skeletal muscle calcium channel.
 
Varadi G, Lory P, Schultz D, Varadi M, Schwartz A (Department of Pharmacology and Cell Biophysics, University of Cincinnati, Ohio 45267-0575, USA)
 
IN: Nature 1991; 352(6331):159-162
Impact Factor(s) of Nature: 29.273 (2005), 32.182 (2004), 30.979 (2003), 30.432 (2002), 27.955 (2001)

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ABSTRACT: The L-type voltage-dependent calcium channel is an important link in excitation-contraction coupling of muscle cells (reviewed in refs 2 and 3). The channel has two functional characteristics: calcium permeation and receptor sites for calcium antagonists. In skeletal muscle the channel is a complex of five subunits, alpha 1, alpha 2, beta, gamma and delta. Complementary DNAs to these subunits have been cloned and their amino-acid sequences deduced. The skeletal muscle alpha 1 subunit cDNA expressed in L cells manifests as specific calcium-ion permeation, as well as sensitivity to the three classes of organic calcium-channel blockers. We report here that coexpression of the alpha 1 subunit with other subunits results in significant changes in dihydropyridine binding and gating properties. The available number of drug receptor sites increases 10-fold with an alpha 1 beta combination, whereas the affinity of the dihydropyridine binding site remains unchanged. Also, the presence of the beta subunit accelerates activation and inactivation kinetics of the calcium-channel current.

TYPE OF PUBLICATION: Original article

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• Bodi I, Mikala G, Koch SE, Akhter SA, Schwartz A. The L-type calcium channel in the heart: the beat goes on. J Clin Invest 2005. 115: 3306-3317.
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