fototransductiecascade
The phototransduction cascade is the biological process by which light energy is converted into an electrical signal in photoreceptor cells of the retina. In the vertebrate eye, this process occurs in rod and cone cells. When a photon strikes a photopigment molecule called rhodopsin (in rods) or a similar cone opsin, it causes a conformational change in a protein called retinal, which is bound to the opsin. This change activates the opsin.
The activated opsin then binds to and activates a G protein called transducin. Activated transducin, in turn,
When cGMP levels fall, these ion channels close. The closure of these channels causes a hyperpolarization of