Document Detail


Biological significance of phosphorylation and myristoylation in the regulation of cardiac muscle proteins.
MedLine Citation:
PMID:  9406155     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Post-translational modification has long been recognized as a way in which the properties of proteins may be subtly altered after synthesis of the polypeptide chain is complete. Amongst the moieties most commonly encountered covalently attached to proteins are oligosaccharides, phosphate, acetyl, formyl and nucleosides. Protein phosphorylation and dephosphorylation is one of the most prevalent and best understood modifications employed in cellular regulation. The bovine heart calmodulin-dependent cyclic nucleotide phosphodiesterase (CaMPEDE) can be phosphorylated by cAMP-dependent protein kinase, resulting in a decrease in the enzyme's affinity for Ca2+ and calmodulin (CaM). The phosphorylation of CaMPDE is blocked by Ca2+ and CaM and reversed by the CaM-dependent phosphatase (calcineurin). The dephosphorylation is accompanied by an increase in the affinity of the phosphodiesterase for CaM. Analysis of the complex regulatory properties of CaMPDE has led to the suggestion that fluxes of cAMP and Ca2+ during cell activations are closely coupled and that the CaMPDE play a key role in the signal coupling phenomenon. The high molecular weight calmodulin binding protein (HMWCaMBP) was phosphorylated by cAMP-dependent protein kinase. Phosphorylation of HMWCBP was higher in the absence of Ca2+/CaM then in the presence of Ca2+/CaM and reversed by the CaM-dependent phosphatase. Recently, it has become apparent that the binding of myristate to proteins is also widespread in eukaryotic cells and viruses and certainly is of great importance to the correct functioning of an organism. Myristoyl CoA:protein N-myristoyltransferase (NMT) catalyses the attachment of myristate to the amino-terminal glycine residue of various signal transduction proteins. Cardiac tissue express high levels of cAMP-dependent protein kinase whose catalytic subunit is myristoylated. The subcellular localization of bovine cardiac muscle NMT indicated a majority of the activity was localized in cytoplasm. Under native conditions the enzyme exhibited an apparent molecular mass of 50 kDa. Recovery of NMT activity, from both cytosol and particulate fractions, was found to be higher than the total activity in crude homogenates, suggesting that particulate fraction may contain an inhibitory activity towards NMT. Research in our laboratory has been focusing on the covalent modification of proteins and regulation of various signal transduction proteins. This special review is designed to summarize some aspects of the current work on co- and post-translational modification of proteins in cardiac muscle.
Authors:
R V Raju; R Kakkar; J M Radhi; R K Sharma
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Review    
Journal Detail:
Title:  Molecular and cellular biochemistry     Volume:  176     ISSN:  0300-8177     ISO Abbreviation:  Mol. Cell. Biochem.     Publication Date:  1997 Nov 
Date Detail:
Created Date:  1998-01-23     Completed Date:  1998-01-23     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  0364456     Medline TA:  Mol Cell Biochem     Country:  NETHERLANDS    
Other Details:
Languages:  eng     Pagination:  135-43     Citation Subset:  IM    
Affiliation:
Department of Pathology, College of Medicine, Royal University Hospital, University of Saskatchewan, Saskatoon, Canada.
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MeSH Terms
Descriptor/Qualifier:
Acyltransferases / metabolism
Animals
Calcium / metabolism
Calmodulin / metabolism*
Calmodulin-Binding Proteins / metabolism*
Cattle
Cyclic AMP / metabolism*
Cyclic AMP-Dependent Protein Kinases / metabolism
Glycoproteins / genetics,  metabolism
Humans
Myocardium / enzymology*
Phosphoric Monoester Hydrolases / metabolism
Phosphorylation
Protein Processing, Post-Translational
Signal Transduction
Chemical
Reg. No./Substance:
0/Calmodulin; 0/Calmodulin-Binding Proteins; 0/Glycoproteins; 60-92-4/Cyclic AMP; 7440-70-2/Calcium; EC 2.3.-/Acyltransferases; EC 2.3.1.97/glycylpeptide N-tetradecanoyltransferase; EC 2.7.11.11/Cyclic AMP-Dependent Protein Kinases; EC 3.1.3.-/Phosphoric Monoester Hydrolases

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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