Inhibitory gamma subunit of the rod-specific cGMP phosphodiesterase (PDE6) complex, which hydrolyzes 3',5'-cyclic GMP in the phototransduction cascade. The PDE6 holoenzyme consists of two catalytic subunits (PDE6A and PDE6B) and two inhibitory gamma subunits. Light-activated GNAT1 relieves gamma subunit-mediated inhibition, enabling the catalytic subunits to hydrolyze cGMP and thereby mediate visual signal transduction and amplification. . This is the function of Ensembl gene identifier ENSG00000185527 (PDE6G, phosphodiesterase 6G).