STRUCTURE AND PHYSIOLOGY OF PHOTORECEPTOR CGMP-GATED CATION CHANNELS

The primary sequence of two subunits of the rod and one subunit of the cone cGMP-gated channel have been described, but describing how struc ture determines function is only just beginning. The discovery that th e affinity of the rod channel for its agonist can be modulated indicat es that the relationship between intracellular cGMP and the channel's open probability (current) during the course of the photoresponse may be more complex than previously thought.