cGMP is a secondary messenger in phototransduction in the eye. In the photoreceptors of the mammalian eye, the presence of light activates phosphodiesterase, which degrades cGMP. The sodium ion channels in photoreceptors are cGMP-gated, so degradation of cGMP causes sodium channels to close, which leads to the hyperpolarization of the photoreceptor's plasma membrane and ultimately to visual information being sent to the brain.
. CNG- . (: (Kramer and Molokanova, 2001) B. β- α- CNG- ( , .). ( ). (: (Trudeau and Zagotta, 2002)
