Abstract
Abstract: :
Purpose: This study was designed to investigate the presence of a Ca2+-modulated membrane guanylate cyclase transduction system in the photoreceptor-bipolar synaptic region.Methods: A combination of peptide competition, surface plasmon resonance binding, and deletion mutation studies were used.Results: The study shows the molecular presence of the Ca2+-dependent S100ß-regulated ROS-GC1 transduction system in the membrane fraction of the photoreceptor-bipolar synaptic region. Two critical S100ß-regulatory sites in ROS-GC1 have been identified. One, a 7 amino acid motif, represents the binding site, the other, a 12 amino acid motif, the transducer site.Conclusion:The findings contradict the existing dogma that in retinal neurons ROS-GC transduction system is solely present in ROS; show that the system is present in the photoreceptr-bipolar neurons; demonstrate that unlike ROS, where ROS-GC is inhibited by Ca2+ spikes,it is stimulated; and the mechanism of stimulation has been solved at the molecular level.