Description_x000D_ General description_x000D_ GRK7 is a member of the G protein-coupled receptor kinase subfamily and is a Ser/Thr protein kinase. GRK7 is specifically expressed in the retina and has been shown to phosphorylate cone opsins and initiate their deactivation. GRK7 catalyzes rhodopsin phosphorylation in a light-dependent manner. GRK7 co-localizes with GRK1 in human cone outer segments. PKA phosphorylates GRK7 at Ser(23) and Ser(36) in vitro and phosphorylation of GRK7 by PKA reduces the ability of GRK7 to phosphorylate rhodopsin in vitro. Since exposure to light causes a decrease in cAMP levels in rod cells, it is proposed that phosphorylation of GRK7 by PKA occurs in the dark._x000D_ Physical form_x000D_ Supplied in 50mM Tris-HCl, pH 7.5, 150mM NaCl, 10mM glutathione, 0.1mM EDTA, 0.25mM DTT, 0.1mM PMSF, 25% glycerol._x000D_ Preparation Note_x000D_ after opening, aliquot into smaller quantities and store at -70 °C. Avoid repeating handling and multiple freeze/thaw cycles_x000D_ Legal Information_x000D_ PRECISIO is a registered trademark of Sigma-Aldrich Co. LLC