Effect of the ILE86TER mutation in the γ subunit of cGMP phosphodiesterase (PDE6) on rod photoreceptor signaling

► We made PDE6 ILE86TER mice lacking the two C-terminal PDE6γ Ile86 and Ile87 residues. ► This mutation in vitro reduces the efficiency of PDE6γ inhibition of PDE6α and PDE6β. ► Light responses of ILE86TER rods decayed more slowly than those of WT rods. ► Experiments with IBMX showed that mutant rods had more spontaneous PDE6 activity. ► The C-terminus of PDE6γ plays an essential role in control of PDE6 activity in vivo.