Retinal rod and cone cGMP phosphodiesterases function as the effector enzymes in the vertebrate visual transduction cascade. This family represents the inhibitory gamma subunit [1], which is also expressed outside retinal tissues and has been shown to interact with the G-protein-coupled receptor kinase 2 signalling system to regulate the epidermal growth factor- and thrombin-dependent stimulation of p42/p44 mitogen-activated protein kinase in human embryonic kidney 293 cells [2].

1: Direct interaction of the inhibitory gamma-subunit of Rod cGMP phosphodiesterase (PDE6) with the PDE6 GAFa domains. Muradov KG, Granovsky AE, Schey KL, Artemyev NO; Biochemistry 2002;41:3884-3890. PMID:11900530

2: The inhibitory gamma subunit of the type 6 retinal cyclic guanosine monophosphate phosphodiesterase is a novel intermediate regulating p42/p44 mitogen-activated protein kinase signaling in human embryonic kidney 293 cells. Wan KF, Sambi BS, Frame M, Tate R, Pyne NJ; J Biol Chem 2001;276:37802-37808. PMID:11502744