Protein kinase cross-talk: membrane targeting of the beta-adrenergic
receptor kinase by protein kinase C
Proc Natl Acad Sci U S A, 93 (5):
2105-9 (March 1996)Winstel, R Freund, S Krasel, C Hoppe, E Lohse, M J Research Support,
Non-U.S. Gov't United states Proceedings of the National Academy
of Sciences of the United States of America Proc Natl Acad Sci U
S A. 1996 Mar 5;93(5):2105-9..Abstract
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.