P. Kunapuli et al., PHOSPHOLIPID-STIMULATED AUTOPHOSPHORYLATION ACTIVATES THE G-PROTEIN-COUPLED RECEPTOR KINASE GRK5, The Journal of biological chemistry, 269(14), 1994, pp. 10209-10212
G protein-coupled receptor kinases (GRKs) play an important role in me
diating agonist-specific desensitization of numerous G protein-coupled
receptors. GRK5, a recently identified member of the GRK family, unde
rgoes a rapid phospholipid-stimulated autophosphorylation to a stoichi
ometry of similar to 2 mol of phosphate/mol of GRK5. The ability of ph
ospholipids to stimulate autophosphorylation is largely blocked by a g
lutathione S-transferase fusion protein containing the last 102 amino
acids of GRK5 (amino acids 489-590), suggesting that this is a primary
region involved in GRK5/phospholipid interaction. Phosphoamino acid d
etermination and mutagenesis studies demonstrate that autophosphorylat
ion of GRK5 occurs primarily at residues Ser-484 and Thr-485. Expressi
on and characterization of a mutant GRK5 that does not autophosphoryla
te (S484A and T485A) reveals that the mutant has a similar to 15-20-fo
ld reduced ability to phosphorylate the beta(2)-adrenerse receptor and
rhodopsin compared to wild type GRK5. These results suggest that phos
pholipid-stimulated autophosphorylation may represent a novel mechanis
m for membrane association and regulation of GRK5 activity,