GRK4
Function
Specifically phosphorylates the activated forms of G protein-coupled receptors. GRK4-alpha can phosphorylate rhodopsin and its activity is inhibited by calmodulin; the other three isoforms do not phosphorylate rhodopsin and do not interact with calmodulin. GRK4-alpha and GRK4-gamma phosphorylate DRD3. Phosphorylates ADRB2.
Post-translational modifications
Palmitoylated.
Sequence Similarities
Belongs to the protein kinase superfamily. AGC Ser/Thr protein kinase family. GPRK subfamily.
Tissue Specificity
Isoform 1, isoform 2, isoform 3, and isoform 4 are expressed in testis. Isoform 4 is expressed in myometrium.
Cellular localization
- Cytoplasm
- Cytoplasm
- Cell cortex
- Both at the cell surface and dispersed in the cytoplasm under basal conditions. Receptor stimulation results in the internalization of GRK4 to the perinuclear area, where colocalization with DRD3 is observed strongly at 5 and 15 minutes. DRD3 and GRK4 colocalize in lipid rafts of renal proximal tubule cells.
Alternative names
GPRK2L, GPRK4, GRK4, G protein-coupled receptor kinase 4, G protein-coupled receptor kinase GRK4, ITI1