We recently reported that a
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2-adrenergic receptor(
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2AR) mutant, Y326A, defective in it
sability to
seque
ster in re
spon
se to agoni
st
stimulation wa
s a poor
sub
strate for G protein-coupled receptorkina
se (GRK)-mediated pho
sphorylation; however, it
s ability to bepho
sphorylated and
seque
stered couldbe re
stored by overexpre
ssing GRK2 [Fergu
son
etal. (1995)
J. Biol. Chem.270, 24782]. In the pre
sentreport, we te
sted the ability of each of the known GRK
s (GRK1-6) topho
sphorylate and re
scue the
seque
stration of the Y326A mutant in HEK-293 cell
s. We demon
stratethat in addition to GRK2, GRK3-6can pho
sphorylate the Y326A mutant and re
scue it
s seque
stration;however, GRK1 wa
s totally ineffectivein re
scuing either the pho
sphorylation or the
seque
stration of themutant receptor. We found that theagoni
st-dependent re
scue of Y326A mutant pho
sphorylation by GRK2, -3,and -5 wa
s a
ssociated withthe agoni
st-dependent re
scue of
seque
stration. In contra
st,overexpre
ssion of GRK4 and -6 led mainly toagoni
st-independent pho
sphorylation of the Y326A mutant accompanied byincrea
sed ba
sal receptor
seque
stration. Our re
sult
s demon
strate that pho
sphorylation
per se, but not the interaction with a
specificGRK, i
s required to facilitate
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2AR
seque
stration.