Phospholipid-stimulated autophosphorylation activates the G protein-coupled receptor kinase GRK5.
G protein-coupled receptor kinases (GRKs) play an important role in mediating agonist-specific desensitization of numerous G protein-coupled receptors. GRK5, a recently identified member of the GRK family, undergoes a rapid phospholipid-stimulated autophosphorylation to a stoichiometry of approximately 2 mol of phosphate/mol of GRK5. The ability of phospholipids to stimulate autophosphorylation is largely blocked by a glutathione 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 determination and mutagenesis studies demonstrate that autophosphorylation of GRK5 occurs primarily at residues Ser-484 and Thr-485. Expression and characterization of a mutant GRK5 that does not autophosphorylate (S484A and T485A) reveals that the mutant has a approximately 15-20-fold reduced ability to phosphorylate the beta 2-adrenergic receptor and rhodopsin compared to wild type GRK5. These results suggest that phospholipid-stimulated autophosphorylation may represent a novel mechanism for membrane association and regulation of GRK5 activity.
Kunapuli
P
P
Department of Pharmacology, Jefferson Cancer Institute, Thomas Jefferson University, Philadelphia, Pennsylvania 19107.
Gurevich
V V
VV
Benovic
J L
JL
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured; D006224:Cricetinae; D017931:DNA Primers; D054774:G-Protein-Coupled Receptor Kinase 5; D019204:GTP-Binding Proteins / Q000378:metabolism*; D007915:Lepidoptera; D008969:Molecular Sequence Data; D010743:Phospholipids / Q000378:metabolism*; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism*
D017931:DNA Primers; D010743:Phospholipids; D020794:Receptor Protein-Tyrosine Kinases; D017346:Protein Serine-Threonine Kinases; D054774:G-Protein-Coupled Receptor Kinase 5; D019204:GTP-Binding Proteins