Title: Site-Specific Phosphorylation of the Skeletal Muscle Receptor for Calcium-Channel Blockers by cAMP-Dependent Protein Kinase
Abstract: Voltage-operated calcium channels are important factors in excitation-contraction coupling of cardiac and smooth muscle. The cardiac L-type calcium channel was the first channel known to be modified by hormones [11, 21, 31, 32]. The activation of the cardiac β-adrenergic receptor stimulates cAMP levels and increases three- to four-fold voltage-dependent opening (Po) of the channel. A similar increase in Po has been observed in hippocampal neurons [10]. Catecholamines also stimulate the calcium influx into myotubes [25], suggesting that stimulation of L-type calcium current by catecholamines is a widespread phenomenon. The stimulation of the calcium current is probably caused by the activation of cAMP-dependent protein kinase. The perfusion of a cardiac myocyte with active cAMP-dependent protein kinase elicits the same response as stimulation of the β-receptor [15], suggesting that phosphorylation of the calcium channel itself or a closely associated protein modifies the open probability of the channel. The Po of cardiac and skeletal muscle calcium channels may be affected also by the a-subunit of the GTP-binding protein Gs [33,34].
Publication Year: 1988
Publication Date: 1988-01-01
Language: en
Type: book-chapter
Indexed In: ['crossref']
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Cited By Count: 3
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