Atwood et al. BMC Genomics 2011, 12:14 http://www.biomedcentral.com/1471-2164/12/14 R E S E A R C H A R T I C L E Open Access Expression of G protein-coupled receptors and related proteins in HEK293, AtT20, BV2, and N18 cell lines as revealed by microarray analysis Brady K Atwood1,3, Jacqueline Lopez2, James Wager-Miller1, Ken Mackie1, Alex Straiker1* Abstract Background: G protein coupled receptors (GPCRs) are one of the most widely studied gene superfamilies. Thousands of GPCR research studies have utilized heterologous expression systems such as human embryonic kidney cells (HEK293). Though often treated as ‘blank slates’, these cell lines nevertheless endogenously express GPCRs and related signaling proteins. The outcome of a given GPCR study can be profoundly influenced by this largely unknown complement of receptors and/or signaling proteins. Little easily accessible information exists that describes the expression profiles of the GPCRs in cell lines. What is accessible is often limited in scope - of the hundreds of GPCRs and related proteins, one is unlikely to find information on expression of more than a dozen proteins in a given cell line. Microarray technology has allowed rapid analysis of mRNA levels of thousands of candidate genes, but though often publicly available, the results can be difficult to efficiently access or even to interpret. Results: To bridge this gap, we have used microarrays to measure the mRNA levels of a comprehensive profile of non-chemosensory GPCRs and over a hundred GPCR signaling related gene products in four cell lines frequently used for GPCR research: HEK293, AtT20, BV2, and N18. Conclusions: This study provides researchers an easily accessible mRNA profile of the endogenous signaling repertoire that these four cell lines possess. This will assist in choosing the most appropriate cell line for studying GPCRs and related signaling proteins. It also provides a better understanding of the potential interactions between GPCRs and those signaling proteins. Background The G protein-coupled receptor (GPCR) gene superfam- ily consists of hundreds of members that are widely expressed in all tissues and serve as receptors for a diverse complement of ligands. Approximately 100 of these receptors are considered orphan GPCRs, in that no endogenous ligand has been confirmed for them [1]. Characterized by having seven transmembrane alpha- helical domains [2], GPCRs mediate a wide spectrum of cellular processes ranging from cell growth to neuro- transmission [1-3]. A number of classification systems for GPCRs have been developed as bioinformatic tools [3-5]. One of the most commonly used GPCR * Correspondence: straiker@indiana.edu 1Department of Psychological & Brain Sciences, The Gill Center for Biomolecular Science, Indiana University, Bloomington, Indiana, USA Full list of author information is available at the end of the article classification systems, the one set forth by Kolakowski and developed by Vriend [4,6,7], groups GPCRs into six classes based on structural similarities to prototypical receptors. Class A GPCRs are the most abundant (>80% of all GPCRs), defined by a high sequence homology to rhodopsin, and include the chemosensory receptors. Class B GPCRs are also known as secretin-like recep- tors. Class C GPCRs are the metabotropic glutamate- like receptors. Class F/S receptors consist of frizzled/ smoothened receptors, though there is debate about their ability to couple to G proteins [2]. Class D/Fungal pheromone and Class E/cAMP receptors are absent in mammals. On activation via ligand binding, GPCRs couple to het- erotrimeric G proteins composed of three subunits: Ga, b and g. G protein a subunits are classified as members of one of four groups: Gi/o, Gs, Gq, and G12/13 [8]. © 2011 Atwood et al; 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.