Abstract
G protein-coupled receptor kinases (GRK), such as the beta-adrenergic receptor kinase (beta ARK) and rhodopsin kinase, specifically phosphorylate the activated form of G protein-coupled receptors. To identify additional members of the GRK family, we screened a human heart cDNA library by low stringency hybridization using the catalytic domains of two beta ARK isoforms. Here we report the isolation of a cDNA that encodes a 576-amino-acid protein kinase, termed GRK6, that has significant homology with GRK5 (70.1% amino acid identity), IT11 (68.5%), rhodopsin kinase (47.1%), and beta ARK (37.4%). RNA blot analysis of GRK6 with selected human tissues reveals two distinct mRNAs of 3 and 2.4 kilobases with a distribution very similar to that of beta ARK (i.e. brain, skeletal muscle > pancreas > heart, lung, kidney, placenta > liver). GRK6, overexpressed in Sf9 insect cells using the baculovirus system, was able to phosphorylate both the beta 2-adrenergic receptor and rhodopsin in a stimulus-dependent fashion, although it was significantly less active then beta ARK on these substrates. These data extend the family of GRKs and suggest that GRK6 may have a substrate specificity quite distinct from beta ARK and rhodopsin kinase.
Publication types
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Comparative Study
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Amino Acid Sequence
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Animals
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Base Sequence
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Blotting, Northern
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Brain / enzymology*
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Cell Line
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Cloning, Molecular*
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Cyclic AMP-Dependent Protein Kinases*
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Eye Proteins*
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Fetus
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G-Protein-Coupled Receptor Kinase 1
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G-Protein-Coupled Receptor Kinases
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GTP-Binding Proteins / metabolism*
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Gene Expression*
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Gene Library
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Humans
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Molecular Sequence Data
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Moths
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Multigene Family*
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Myocardium / enzymology*
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Organ Specificity
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Protein Kinases / biosynthesis*
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Protein Kinases / genetics
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Protein Serine-Threonine Kinases*
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RNA, Messenger / biosynthesis
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RNA, Messenger / isolation & purification
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RNA, Messenger / metabolism
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Receptor Protein-Tyrosine Kinases / biosynthesis
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Receptor Protein-Tyrosine Kinases / isolation & purification
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Receptor Protein-Tyrosine Kinases / metabolism*
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Restriction Mapping
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Sequence Homology, Amino Acid
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Transfection
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beta-Adrenergic Receptor Kinases
Substances
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Eye Proteins
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RNA, Messenger
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Protein Kinases
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Receptor Protein-Tyrosine Kinases
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Protein Serine-Threonine Kinases
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Cyclic AMP-Dependent Protein Kinases
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G-Protein-Coupled Receptor Kinase 1
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GRK1 protein, human
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beta-Adrenergic Receptor Kinases
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G-Protein-Coupled Receptor Kinases
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G-protein-coupled receptor kinase 6
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GTP-Binding Proteins