Linked Life Data

15533936

Source:http://linkedlifedata.com/resource/pubmed/id/15533936

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
4
pubmed:dateCreated
2005-1-24
pubmed:abstractText
The catalytic subunit of cAMP-dependent protein kinase (PKA) is phosphorylated at threonine 197 and serine 338. Phosphorylation of threonine 197, located in the activation loop, is required for coordinating the active site conformation and optimal enzymatic activity. However, this phosphorylation has not been widely appreciated as a regulatory site because of the apparent constitutive nature of the phosphorylation and the general resistance of the kinase to phosphatase treatment. We demonstrate here that the observed resistance of the catalytic subunit to dephosphorylation is due, in part, to the presence of the highly nucleophilic cysteine 199 located proximal to the phosphate on threonine 197. Experiments performed in vitro demonstrated that mutation (cysteine 199 to alanine), oxidation, such as by glutathionylation or internal disulfide bond formation, or alkylation of the C-subunit enhanced its ability to be dephosphorylated. Furthermore, rephosphorylation of reduced C-subunit by PDK1 created a cycle whereby the inactive kinase could be reactivated. To demonstrate that thiol modification of PKA can lead to enhanced dephosphorylation in vivo, PC12 cells were treated with N-ethylmaleimide (NEM). Such treatment resulted in complete PKA inactivation and dephosphorylation of threonine 197. This effect of NEM was contingent upon prior treatment of the cells with PKA activators, demonstrating the resistance of the holoenzyme to thiol alkylation-mediated dephosphorylation. Our results also demonstrated that NEM treatment of PC12 cells enhanced the dephosphorylation of the protein kinase Calpha activation loop, suggesting a common mechanism of regulation among members of the AGC family of kinases.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jan
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
28
pubmed:volume
280
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
2750-8
pubmed:dateRevised
2009-11-19
pubmed:meshHeading
pubmed-meshheading:15533936-Animals, pubmed-meshheading:15533936-Binding Sites, pubmed-meshheading:15533936-Blotting, Western, pubmed-meshheading:15533936-Cyclic AMP-Dependent Protein Kinases, pubmed-meshheading:15533936-Cysteine, pubmed-meshheading:15533936-Disulfides, pubmed-meshheading:15533936-Ethylmaleimide, pubmed-meshheading:15533936-Glutathione, pubmed-meshheading:15533936-Mice, pubmed-meshheading:15533936-Models, Molecular, pubmed-meshheading:15533936-Mutation, pubmed-meshheading:15533936-Oxidative Stress, pubmed-meshheading:15533936-Oxygen, pubmed-meshheading:15533936-PC12 Cells, pubmed-meshheading:15533936-Phosphorylation, pubmed-meshheading:15533936-Protein Conformation, pubmed-meshheading:15533936-Protein Kinase C, pubmed-meshheading:15533936-Protein Kinase C-alpha, pubmed-meshheading:15533936-Protein Structure, Tertiary, pubmed-meshheading:15533936-Rats, pubmed-meshheading:15533936-Sulfhydryl Compounds, pubmed-meshheading:15533936-Threonine, pubmed-meshheading:15533936-Time Factors
pubmed:year
2005
pubmed:articleTitle
Enhanced dephosphorylation of cAMP-dependent protein kinase by oxidation and thiol modification.
pubmed:affiliation
Howard Hughes Medical Institute, Department of Chemistry and Biochemistry and Department of Pharmacology, The University of California, San Diego, La Jolla, California 92093-0654, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.