Structural properties of voltage-dependent calcium channels.
Following purification using Ca2+ channel drugs as ligands, the skeletal muscle Ca2+ channel was shown to be a five-subunit structure containing one large (175 kDa) protein that is the pore and four auxiliary subunits. Each subunit has been cloned and expression studies are proceeding rapidly. Particular success has been made in structure-function studies of excitation-contraction coupling using a Ca2+ channel-free mutant muscle. The work confirmed the suggestion made from physiological studies that muscle Ca2+ channels serve dual roles: passing Ca2+ and triggering Ca2+ release from an intracellular organelle. A variety of other predictions about the structure of Ca2+ channels have been reviewed here and these may soon be possible to test. Such concrete predictions along with analogies to studies on other voltage-dependent ion channels should speed progress in structure-function studies of Ca2+ channels.
Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri 63110.
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EW
McCleskey
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MD
Womack
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LA
Fieber
D000818:Animals; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000737:chemistry*; D009119:Muscle Contraction; D017434:Protein Structure, Tertiary; D013329:Structure-Activity Relationship
D015220:Calcium Channels; D002118:Calcium