Document Detail

cAMP-dependent phosphorylation of the cardiac L-type Ca channel: a missing link?
MedLine Citation:
PMID:  8834778     Owner:  NLM     Status:  MEDLINE    
Cardiac inotropic effects of beta adrenergic agonists occur mainly through an increase in L-type (class C) calcium channel activity. This response has been attributed to phosphorylation of the L-type Ca channel, or a closely associated protein, by the cAMP-dependent protein kinase A (PKA). Among the three subunits forming the cardiac L-type Ca channel (alpha 1, beta and alpha 2-delta), biochemical studies have revealed that two subunits, alpha 1 and beta, are phosphorylated in vitro by protein kinase A, the alpha 1 subunit being the primary target. However, attempts to reconstitute the cAMP-dependent regulation of the expressed class C Ca channel, either in Xenopus oocytes or in cell lines, have provided contradictory results. We were unable to detect cAMP-dependent modulation of class C alpha 1 subunit Ca channels expressed in Xenopus oocytes, even when coinjected with auxiliary subunits beta and alpha 2-delta. Nevertheless, activity of Ca channels recorded from cardiac-mRNA injected oocytes was potentiated by injection of cAMP or PKA, even when expression of the beta subunit was suppressed using antisense oligonucleotide. Taken together, these results indicate that cAMP-dependent regulation does not exclusively involve the alpha 1 and the beta subunits of the Ca channel and suggest that unidentified protein(s), expressed in cardiac tissue, are most likely necessary.
P Charnet; P Lory; E Bourinet; T Collin; J Nargeot
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Review    
Journal Detail:
Title:  Biochimie     Volume:  77     ISSN:  0300-9084     ISO Abbreviation:  Biochimie     Publication Date:  1995  
Date Detail:
Created Date:  1996-12-05     Completed Date:  1996-12-05     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  1264604     Medline TA:  Biochimie     Country:  FRANCE    
Other Details:
Languages:  eng     Pagination:  957-62     Citation Subset:  IM    
Centre de Recherche de Biochimie Macromoléculaire, CNRS UPR 9008, INSERM U249, Montpellier, France.
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MeSH Terms
Calcium Channels / metabolism*
Cyclic AMP / metabolism*
Cyclic AMP-Dependent Protein Kinases / metabolism
Myocardium / cytology,  metabolism
Receptors, Adrenergic, beta / metabolism*
Reg. No./Substance:
0/Calcium Channels; 0/Receptors, Adrenergic, beta; 60-92-4/Cyclic AMP; EC AMP-Dependent Protein Kinases

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