Interaction between the conserved region in the C-terminal domain of GRK2 and rhodopsin is necessary for GRK2 to catalyze receptor phosphorylation.
The C-terminal domain of G protein-coupled receptor kinases (GRKs) consists of a conserved region and a variable region, and the variable region has been shown to direct the membrane translocation of cytosolic enzymes. The present work has revealed that the C-terminal domain may also be involved in kinase-receptor interaction that is primarily mediated by the conserved region. Truncation of the C-terminal domain or deletion of the conserved region in this domain of GRK2 resulted in a complete loss of its ability to phosphorylate rhodopsin and in an obvious decrease in its sensitivity to receptor-mediated phosphorylation of a peptide substrate. On the contrary, deletion of the betagamma subunit binding region in the C-terminal domain of GRK2 did not significantly alter the ability of the enzyme to phosphorylate rhodopsin. In addition, the recombinant proteins that represent the C-terminal domain and the conserved region of GRK2 could inhibit GRK2-mediated phosphorylation of rhodopsin and receptor-mediated activation of GRK2 but not GRK2-mediated phosphorylation of the peptide substrate. Furthermore, the conserved region as well as the C-terminal domain could directly bind rhodopsin in vitro. These results indicate that the C-terminal domain, or more precisely, the conserved region of this domain, is important for enzyme-receptor interaction and that this interaction is required for GRK2 to catalyze receptor phosphorylation.
Gan
X Q
XQ
Shanghai Institute of Biochemistry, Shanghai 200031, People's Republic of China.
Wang
J Y
JY
Yang
Q H
QH
Li
Z
Z
Liu
F
F
Pei
G
G
Li
L
L
D000319:Adrenergic beta-Antagonists; D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D017124:Conserved Sequence; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics; D054769:G-Protein-Coupled Receptor Kinase 2; D016296:Mutagenesis; D010446:Peptide Fragments / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D011485:Protein Binding; D011943:Receptors, Adrenergic, beta / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D012243:Rhodopsin / Q000378:metabolism*; D017384:Sequence Deletion; D051552:beta-Adrenergic Receptor Kinases; D020741:rho GTP-Binding Proteins / Q000378:metabolism
D000319:Adrenergic beta-Antagonists; D010446:Peptide Fragments; D011943:Receptors, Adrenergic, beta; D011994:Recombinant Proteins; D012243:Rhodopsin; D017868:Cyclic AMP-Dependent Protein Kinases; C496567:GRK2 protein, human; D051552:beta-Adrenergic Receptor Kinases; D054769:G-Protein-Coupled Receptor Kinase 2; D020741:rho GTP-Binding Proteins