G protein-coupled receptor kinase 7 (GRK7)

G protein-coupled receptor kinase 7 (GRK7) is a retina-specific serine/threonine kinase acting in cone photoreceptor cells, where it phosphorylates cone opsins (photopsins) upon light activation[3][7]. This phosphorylation initiates the shutoff of the cone photoresponse and allows adaptation to changing light conditions, which is essential for high acuity color vision in the fovea. GRK7 is closely related to GRK1 (rhodopsin kinase), but is specialized for cones while GRK1 operates in rods[3]. Post-translational modifications, including geranylgeranylation and α-carboxyl methylation, regulate GRK7's ability to recognize color opsins. Structural features include domain homology to other GRKs: an N-terminal RGS homology domain, a central kinase domain, and a C-terminal lipid-binding domain important for membrane localization[10]. Genetic variations in GRK7 may contribute to inherited retinal diseases, although direct pharmacological targeting is not currently reported[7].

Other names

Rhodopsin kinase GRK7GRK7GPRK7cone opsin kinaseiodopsin kinaseG protein-coupled receptor kinase GRK7

Not applicable for drugs (no drugs directly targeting GRK7 reported). Biochemically, GRK7 phosphorylates light-activated cone opsins, decreasing their activity and triggering binding by arrestin proteins (notably arrestin-4), which shuts off G protein activation and ends the photoresponse[3][7].