Abstract
The compartmentalization of second messenger-activated protein kinases contributes to the fidelity of hormone-mediated signal transduction events. For example, the cAMP-dependent protein kinase is tethered at specific intracellular locations through association with A-kinase anchoring proteins (AKAPs). We now report the cloning of mAKAP, an anchoring protein found predominantly in heart, skeletal muscle and brain, and whose expression is induced in neonatal ventriculocytes by treatment with hypertrophic stimuli. mAKAP is targeted to the nuclear membrane of differentiated myocytes. Analysis of mAKAP-green fluorescent protein (GFP) fusion constructs revealed that nuclear membrane targeting is conferred by two regions of the protein, between residues 772-915 and 915-1065, which contain spectrin-like repeat sequences. Heterologous expression of the mAKAP targeting sequences displaced the endogenous anchoring protein from the nuclear membrane, demonstrating that mAKAP targeting is saturable. Collectively, these data suggest that a domain containing spectrin-like repeats mediates targeting of the anchoring protein mAKAP and the cAMP-dependent protein kinase holoenzyme to the nuclear membrane in response to differentiation signals.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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A Kinase Anchor Proteins
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Adaptor Proteins, Signal Transducing*
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Animals
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Animals, Newborn
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Antibodies
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Carrier Proteins / chemistry
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Carrier Proteins / genetics
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Carrier Proteins / metabolism*
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Cell Differentiation / physiology
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Chromosome Mapping
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Cloning, Molecular
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Cyclic AMP-Dependent Protein Kinases / analysis*
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Fluorescent Antibody Technique
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Gene Expression Regulation, Enzymologic
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Heart Ventricles / cytology
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Humans
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Microscopy, Confocal
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Molecular Sequence Data
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Muscle Fibers, Skeletal / chemistry*
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Muscle Fibers, Skeletal / cytology
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Muscle Fibers, Skeletal / enzymology
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Mutagenesis / physiology
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Myocardium / chemistry*
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Myocardium / cytology
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Myocardium / enzymology
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Nuclear Envelope / chemistry*
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Nuclear Envelope / enzymology
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Peptide Fragments / analysis
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Peptide Fragments / immunology
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Protein Binding / physiology
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Protein Structure, Tertiary
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Rats
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Sequence Homology, Amino Acid
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Spectrin / analysis
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Spectrin / chemistry
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Spectrin / genetics
Substances
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A Kinase Anchor Proteins
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AKAP6 protein, human
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Adaptor Proteins, Signal Transducing
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Akap6 protein, rat
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Antibodies
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Carrier Proteins
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Peptide Fragments
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Spectrin
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Cyclic AMP-Dependent Protein Kinases