title: A calcium-relay mechanism in vertebrate phototransduction.
abstract: Calcium-signaling in cells requires a fine-tuned system of calcium-transport proteins involving ion channels, exchangers, and ion-pumps but also calcium-sensor proteins and their targets. Thus, control of physiological responses very often depends on incremental changes of the cytoplasmic calcium concentration, which are sensed by calcium-binding proteins and are further transmitted to specific target proteins. This Review will focus on calcium-signaling in vertebrate photoreceptor cells, where recent physiological and biochemical data indicate that a subset of neuronal calcium sensor proteins named guanylate cyclase-activating proteins (GCAPs) operate in a calcium-relay system, namely, to make gradual responses to small changes in calcium. We will further integrate this mechanism in an existing computational model of phototransduction showing that it is consistent and compatible with the dynamics that are characteristic for the precise operation of the phototransduction pathways.
authors.affiliation: Department of Neurosciences, Biochemistry Group, University of Oldenburg, Carl-von-Ossietzky-Strasse 9-11, D-26129 Oldenburg, Germany. karl.w.koch@uni-oldenburg.de
authors.forename: Karl-Wilhelm
authors.initials: KW
authors.lastname: Koch
authors.forename: Daniele
authors.initials: D
authors.lastname: Dell'orco
mesh_terms: D000818:Animals; D020013:Calcium Signaling / Q000502:physiology*; D051604:Guanylate Cyclase-Activating Proteins / Q000378:metabolism; D006801:Humans; D055537:Light Signal Transduction / Q000502:physiology*; D020419:Photoreceptor Cells, Vertebrate / Q000378:metabolism*
chemical_list: C496739:GUCA1B protein, human; D051604:Guanylate Cyclase-Activating Proteins