BMC Evolutionary Biology BioMed Central Research article Open Access On the origins of arrestin and rhodopsin Carlos E Alvarez1,2,3 Address: 1Center for Molecular and Human Genetics, The Research Institute at Nationwide Children's Hospital, Columbus, OH, 43205, USA, 2Department of Pediatrics, The Ohio State University College of Medicine, Columbus, OH, 43210, USA and 3Novartis Institutes of BioMedical Research, CH-4002 Basel, Switzerland Email: Carlos E Alvarez -
[email protected] Published: 29 July 2008 Received: 11 January 2008 Accepted: 29 July 2008 BMC Evolutionary Biology 2008, 8:222 doi:10.1186/1471-2148-8-222 This article is available from: http://www.biomedcentral.com/1471-2148/8/222 © 2008 Alvarez; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Abstract Background: G protein coupled receptors (GPCRs) are the most numerous proteins in mammalian genomes, and the most common targets of clinical drugs. However, their evolution remains enigmatic. GPCRs are intimately associated with trimeric G proteins, G protein receptor kinases, and arrestins. We conducted phylogenetic studies to reconstruct the history of arrestins. Those findings, in turn, led us to investigate the origin of the photosensory GPCR rhodopsin. Results: We found that the arrestin clan is comprised of the Spo0M protein family in archaea and bacteria, and the arrestin and Vps26 families in eukaryotes. The previously known animal arrestins are members of the visual/beta subfamily, which branched from the founding "alpha" arrestins relatively recently.