Rod and cone photoreceptor guanosine 3′5′-cyclic-monophosphate phosphodiesterases (PDEs) are classified into the PDE6 family of cyclic nucleotide PDEs. A unique feature of the PDE6 enzymes is the presence of inhibitory γ-subunits (Pγ). The inhibitory interaction between Pγ and the rod PDE6αβ catalytic subunits is critically important for understanding the mechanism of phototransduction. Recent insights into the molecular interface between Pγ and PDE6αβ have been achieved using mutagenesis of Pγ, fluorescence labeling, and crosslinking approaches.
