Abstract
Activation of G-protein-coupled receptors (GPCRs) mobilizes compartmentalized pulses of cyclic AMP. The main cellular effector of cAMP is protein kinase A (PKA), which is assembled as an inactive holoenzyme consisting of two regulatory (R) and two catalytic (PKAc) subunits. cAMP binding to R subunits dissociates the holoenzyme and releases the catalytic moiety, which phosphorylates a wide array of cellular proteins. Reassociation of PKAc and R components terminates the signal. Here we report that the RING ligase praja2 controls the stability of mammalian R subunits. Praja2 forms a stable complex with, and is phosphorylated by, PKA. Rising cAMP levels promote praja2-mediated ubiquitylation and subsequent proteolysis of compartmentalized R subunits, leading to sustained substrate phosphorylation by the activated kinase. Praja2 is required for efficient nuclear cAMP signalling and for PKA-mediated long-term memory. Thus, praja2 regulates the total concentration of R subunits, tuning the strength and duration of PKA signal output in response to cAMP.
© 2011 Macmillan Publishers Limited. All rights reserved
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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A Kinase Anchor Proteins / genetics
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A Kinase Anchor Proteins / metabolism
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Animals
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Cell Line, Tumor
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Cyclic AMP / metabolism
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Cyclic AMP Response Element-Binding Protein / metabolism
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Cyclic AMP-Dependent Protein Kinases / chemistry
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Cyclic AMP-Dependent Protein Kinases / genetics
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Cyclic AMP-Dependent Protein Kinases / metabolism*
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DNA-Binding Proteins / genetics
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DNA-Binding Proteins / metabolism*
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Enzyme Activation
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Enzyme Stability*
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HEK293 Cells
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Humans
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Long-Term Potentiation / physiology
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Mice
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Neuroblastoma
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Neurons / cytology
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Neurons / metabolism
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Protein Subunits / genetics
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Protein Subunits / metabolism
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Proto-Oncogene Proteins c-fos / genetics
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Proto-Oncogene Proteins c-fos / metabolism
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Rats
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Recombinant Fusion Proteins / genetics
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Recombinant Fusion Proteins / metabolism
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Signal Transduction / physiology*
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Two-Hybrid System Techniques
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Ubiquitin-Protein Ligases / genetics
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Ubiquitin-Protein Ligases / metabolism*
Substances
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A Kinase Anchor Proteins
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Cyclic AMP Response Element-Binding Protein
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DNA-Binding Proteins
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Protein Subunits
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Proto-Oncogene Proteins c-fos
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Recombinant Fusion Proteins
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Cyclic AMP
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PJA2 protein, mouse
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Pja2 protein, rat
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Ubiquitin-Protein Ligases
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Cyclic AMP-Dependent Protein Kinases