GRK7 (G protein-coupled receptor kinase 7) is a retina-specific kinase that plays a crucial role in cone photoreceptor function and visual signal termination. GRK7 is expressed exclusively in cone outer segments in humans and other mammals, where it phosphorylates light-activated cone opsins to initiate signal shutoff 1 2. The kinase exhibits significantly higher enzymatic activity than the rod-specific GRK1, with 32-fold higher Vmax values, contributing to the rapid recovery kinetics characteristic of cone photoresponses 3. GRK7 undergoes cAMP-dependent phosphorylation by protein kinase A (PKA) at serine residues Ser23 and Ser36, which attenuates its enzymatic activity 4. This phosphorylation occurs in darkness when cAMP levels are elevated and is reversed upon light exposure, representing a novel regulatory mechanism for cone adaptation 5 6. The proper localization of GRK7 to cone outer segments is essential for protecting photoreceptors from phototoxicity, as demonstrated in retinal dystrophy models where GRK7 mislocalization correlates with increased light vulnerability 7. Clinically, GRK7 deficiency or mislocalization is associated with abnormal cone deactivation kinetics and may contribute to retinal degeneration, highlighting its therapeutic relevance in inherited retinal diseases 2 7.