title: Calcium signalling and calcium channels: evolution and general principles.
abstract: Calcium as a divalent cation was selected early in evolution as a signaling molecule to be used by both prokaryotes and eukaryotes. Its low cytosolic concentration likely reflects the initial concentration of this ion in the primordial soup/ocean as unicellular organisms were formed. As the concentration of calcium in the ocean subsequently increased, so did the diversity of homeostatic molecules handling calcium. This includes the plasma membrane channels that allowed the calcium entry, as well as extrusion mechanisms, i.e., exchangers and pumps. Further diversification occurred with the evolution of intracellular organelles, in particular the endoplasmic reticulum and mitochondria, which also contain channels, exchanger(s) and pumps to handle the homeostasis of calcium ions. Calcium signalling system, based around coordinated interactions of the above molecular entities, can be activated by the opening of voltage-gated channels, neurotransmitters, second messengers and/or mechanical stimulation, and as such is all-pervading pathway in physiology and pathophysiology of organisms.
authors.affiliation: Faculty of Life Sciences, The University of Manchester, Oxford Road, Manchester, M13 9PT, UK; Achucarro Center for Neuroscience, IKERBASQUE, Basque Foundation for Science, 48011 Bilbao, Spain; Department of Neurosciences, University of the Basque Country UPV/EHU, 48940 Leioa, Spain. Electronic address: Alexej.Verkhratsky@manchester.ac.uk.
authors.forename: Alexei
authors.initials: A
authors.lastname: Verkhratsky
authors.affiliation: Department of Neurobiology, Center for Glial Biology in Medicine, Atomic Force Microscopy & Nanotechnology Laboratories, Civitan International Research Center, Evelyn F. McKnight Brain Institute, University of Alabama, Birmingham, AL 35294, USA; Department of Biotechnology, University or Rijeka, 51000 Rijeka, Croatia. Electronic address: vlad@uab.edu.
authors.forename: Vladimir
authors.initials: V
authors.lastname: Parpura
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000378:metabolism; D020013:Calcium Signaling; D019143:Evolution, Molecular; D006706:Homeostasis
chemical_list: D015220:Calcium Channels; D002118:Calcium
keywords: Calcium; Channels; Eukaryotes; Evolution; Prokaryotes; Transporters