Figure 2.

PDE6 is involved in the phototransduction of vertebrate visual system. The disc membrane and plasma membrane depicted here are localized in photoreceptor cells of retina. Key proteins related to phototransduction cascades are shown in the membranes. The photosensor rhodopsin is integrated into the disc membrane, where G proteins (Gα, β, γ) and PDE6 are attached. In the plasma membrane, CNG channels permeable to Ca²⁺ and Na⁺ stay in an open or close state depending on the dark or light conditions. GC and GCAP are shown in the plasma membrane to maintain the cellular cGMP levels. G proteins: guanine nucleotide-binding protein; GDP: guanosine diphosphate; GTP: guanosine triphosphate; GMP: guanosine monophosphate; GCAP: guanylate cyclase-activating proteins.