Vertebrate rod/cone signalling: photon → 11-cis-retinal → all-trans-retinal → opsin activates transducin → PDE hydrolyses cGMP → CNG channel closes → hyperpolarisation → reduced glutamate release.
Vertebrate rod/cone signalling: photon → 11-cis-retinal → all-trans-retinal → opsin activates transducin → PDE hydrolyses cGMP → CNG channel closes → hyperpolarisation → reduced glutamate release.