Interactions between dihydropyridine receptors and ryanodine receptors in striated muscle

Excitation-contraction coupling in both skeletal and cardiac muscle depends on structural and functional interactions between the voltage-sensing dihydropyridine receptor L-type Ca 2+ channels in the surface/transverse tubular membrane and ryanodine receptor Ca 2+ release channels in the sarcoplasmi...

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Bibliographic Details
Published in:	Progress in Biophysics and Molecular Biology Vol. 79; no. 1; pp. 45 - 75
Main Authors:	Dulhunty, A.F, Haarmann, C.S, Green, D, Laver, D.R, Board, P.G, Casarotto, M.G
Format:	Book Review Journal Article
Language:	English
Published:	England Elsevier Ltd 01-05-2002
Subjects:	Amino Acid Sequence Animals Binding Sites Biophysical Phenomena Biophysics Calcium Channels, L-Type - chemistry Calcium Channels, L-Type - genetics Calcium Channels, L-Type - metabolism Cardiac muscle Dihydropyridine receptor Excitation–contraction coupling Humans Mice Models, Biological Models, Molecular Molecular Sequence Data Muscle Contraction - physiology Muscle, Skeletal - metabolism Myocardium - metabolism Ryanodine receptor Ryanodine Receptor Calcium Release Channel - chemistry Ryanodine Receptor Calcium Release Channel - genetics Ryanodine Receptor Calcium Release Channel - metabolism Skeletal muscle Cardiac muscle Dihydropyridine receptor Excitation–contraction coupling Skeletal muscle Ryanodine receptor
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Summary:	Excitation-contraction coupling in both skeletal and cardiac muscle depends on structural and functional interactions between the voltage-sensing dihydropyridine receptor L-type Ca 2+ channels in the surface/transverse tubular membrane and ryanodine receptor Ca 2+ release channels in the sarcoplasmic reticulum membrane. The channels are targeted to either side of a narrow junctional gap that separates the external and internal membrane systems and are arranged so that bi-directional structural and functional coupling can occur between the proteins. There is strong evidence for a physical interaction between the two types of channel protein in skeletal muscle. This evidence is derived from studies of excitation–contraction coupling in intact myocytes and from experiments in isolated systems where fragments of the dihydropyridine receptor can bind to the ryanodine receptors in sarcoplasmic reticulum vesicles or in lipid bilayers and alter channel activity. Although micro-regions that participate in the functional interactions have been identified in each protein, the role of these regions and the molecular nature of the protein–protein interaction remain unknown. The trigger for Ca 2+ release through ryanodine receptors in cardiac muscle is a Ca 2+ influx through the L-type Ca 2+ channel. The Ca 2+ entering through the surface membrane Ca 2+ channels flows directly onto underlying ryanodine receptors and activates the channels. This was thought to be a relatively simple system compared with that in skeletal muscle. However, complexities are emerging and evidence has now been obtained for a bi-directional physical coupling between the proteins in cardiac as well as skeletal muscle. The molecular nature of this coupling remains to be elucidated.
Bibliography:	ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-3 content type line 23 ObjectType-Review-1
ISSN:	0079-6107 1873-1732
DOI:	10.1016/S0079-6107(02)00013-5