.... the guanine nucleatides that allow the binding of the enzymes to occur. Not only does epinephrine trigger the chemical reactions by bonding to the guanine nucleotides, but they also trigger the production GDP by reducing GTP to its subserviant level. Not all effectors are triggered by simply hormones. Cells in the retinal area of the eye are triggered by photons that strike rhodopsin. When the rhodospin it activates the G protein, transductin, to travel to the effector enzyme, and thus regulates the levels of soduim ions (Na+). The eye cells become hyperpolarized, thus producing a negative charge, signaling visual data to the brain. The two afor .....