Protein kinase cross-talk: membrane targeting of the beta-adrenergic receptor kinase by protein kinase C.
The beta-adrenergic receptor kinase (betaARK) is the prototypical member of the family of cytosolic kinases that phosphorylate guanine nucleotide binding-protein-coupled receptors and thereby trigger uncoupling between receptors and guanine nucleotide binding proteins. Herein we show that this kinase is subject to phosphorylation and regulation by protein kinase C (PKC). In cell lines stably expressing alpha1B- adrenergic receptors, activation of these receptors by epinephrine resulted in an activation of cytosolic betaARK. Similar data were obtained in 293 cells transiently coexpressing alpha1B- adrenergic receptors and betaARK-1. Direct activation of PKC with phorbol esters in these cells caused not only an activation of cytosolic betaARK-1 but also a translocation of betaARK immunoreactivity from the cytosol to the membrane fraction. A PKC preparation purified from rat brain phospborylated purified recombinant betaARK-1 to a stoichiometry of 0.86 phosphate per betaARK-1. This phosphorylation resulted in an increased activity of betaARK-1 when membrane-bound rhodopsin served as its substrate but in no increase of its activity toward a soluble peptide substrate. The site of phosphorylation was mapped to the C terminus of betaARK-1. We conclude that PKC activates betaARK by enhancing its translocation to the plasma membrane.
Winstel
R
R
Laboratory of Molecular Biology, University of Munich, Germany.
Freund
S
S
Krasel
C
C
Hoppe
E
E
Lohse
M J
MJ
D000595:Amino Acid Sequence; D000818:Animals; D016466:CHO Cells; D002451:Cell Compartmentation; D002460:Cell Line; D002462:Cell Membrane / Q000201:enzymology; D006224:Cricetinae; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D004837:Epinephrine / Q000494:pharmacology; D006801:Humans; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry; D010766:Phosphorylation; D011493:Protein Kinase C / Q000502:physiology*; D018340:Receptors, Adrenergic, alpha-1 / Q000378:metabolism*; D011994:Recombinant Proteins; D015398:Signal Transduction; D051552:beta-Adrenergic Receptor Kinases
C547716:ADRA1B protein, human; C547718:Adra1b protein, rat; D010455:Peptides; D018340:Receptors, Adrenergic, alpha-1; D011994:Recombinant Proteins; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; D051552:beta-Adrenergic Receptor Kinases; D004837:Epinephrine