How calcium controls eyesight [04.11.19]
Calcium (Ca) is essential not only for bone mineralization and blood clotting, but also controls a variety of other functions in our body. By active transport mechanisms into and out of the cell Calcium can mediate specific processes, eg. contraction of cells, secretion of molecules, transcellular shuttling of ions or the information transfer of external stimuli. A recent publication of the Hohenheim Department of Biochemistry reviews Ca-mediated signaling in photoreception, i.e. the perception and processing of light stimuli in the eye. Using the classical model organism Drosphila melanogaster (fruit fly), the authors describe Ca-mediated signaling for the adaptation to different light conditions.
Photoreceptor cells in the fly retina © A. Schmitt, A Vogt, K Friedmann, R Paulsen, A Huber, doi: 10.1242/jeb.01527
Original Paper
Voolstra O., Huber A. (2020) Ca2+ Signaling in Drosophila Photoreceptor Cells. In: Islam M. (eds) Calcium Signaling. Advances in Experimental Medicine and Biology, vol 1131. Springer-Verlag Cham
Author information
Department of Biochemistry, Institute of Physiology, University of Hohenheim, Stuttgart, Germany. armin.huber@uni-hohenheim.de.
Abstract
In Drosophila photoreceptor cells, Ca2+ exerts regulatory functions that control the shape, duration, and amplitude of the light response. Ca2+ also orchestrates light adaptation allowing Drosophila to see in light intensity regimes that span several orders of magnitude ranging from single photons to bright sunlight. The prime source for Ca2+ elevation in the cytosol is Ca2+ influx from the extracellular space through light-activated TRP channels. This Ca2+ influx is counterbalanced by constitutive Ca2+ extrusion via the Na+/Ca2+ exchanger, CalX. The light-triggered rise in intracellular Ca2+ exerts its regulatory functions through interaction with about a dozen well-characterized Ca2+ and Ca2+/CaM binding proteins. In this review we will discuss the dynamic changes in Ca2+ concentration upon illumination of photoreceptor cells. We will present the proteins that are known to interact with Ca2+ (/CaM) and elucidate the physiological functions of these interactions.
