Abstract
Compartmentalization of protein kinases with substrates is a mechanism that may promote specificity of intracellular phosphorylation events. We have cloned a low-molecular weight A-kinase Anchoring Protein, called AKAP18, which targets the cAMP-dependent protein kinase (PKA) to the plasma membrane, and permits functional coupling to the L-type calcium channel. Membrane anchoring is mediated by the first 10 amino acids of AKAP18, and involves residues Gly1, Cys4 and Cys5 which are lipid-modified through myristoylation and dual palmitoylation, respectively. Transient transfection of AKAP18 into HEK-293 cells expressing the cardiac L-type Ca2+ channel promoted a 34 9% increase in cAMP-responsive Ca2+ currents. In contrast, a targeting-deficient mutant of AKAP18 had no effect on Ca2+ currents in response to the application of a cAMP analog. Further studies demonstrate that AKAP18 facilitates GLP-1-mediated insulin secretion in a pancreatic beta cell line (RINm5F), suggesting that membrane anchoring of the kinase participates in physiologically relevant cAMP-responsive events that may involve ion channel activation.
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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Amino Acid Sequence
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Animals
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Base Sequence
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Binding Sites
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Calcium Channels / physiology
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Carrier Proteins*
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Cell Line
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Cell Membrane / metabolism
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Cloning, Molecular
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Cyclic AMP / metabolism*
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Cyclic AMP-Dependent Protein Kinases / metabolism*
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DNA, Complementary
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Electric Conductivity
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Glucagon / metabolism
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Glucagon-Like Peptide 1
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Humans
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Insulin / metabolism
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Insulin Secretion
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Membrane Proteins*
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Mice
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Molecular Sequence Data
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Peptide Fragments / metabolism
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Peptide Mapping
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Protein Kinases / genetics
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Protein Kinases / metabolism*
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Protein Precursors / metabolism
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Sequence Homology, Amino Acid
Substances
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A Kinase Anchor Proteins
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AKAP7 protein, human
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Adaptor Proteins, Signal Transducing
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Akap7 protein, mouse
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Calcium Channels
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Carrier Proteins
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DNA, Complementary
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Insulin
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Membrane Proteins
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Peptide Fragments
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Protein Precursors
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Glucagon-Like Peptide 1
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Glucagon
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Cyclic AMP
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Protein Kinases
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Cyclic AMP-Dependent Protein Kinases
Associated data
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GENBANK/AF047715
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GENBANK/AF047716