Table 1 lists a number of putative GPCRs identified by NC-IUPHAR [29], for which preliminary evidence for an endogenous ligand has been published, or for which there exists a potential link to a disease, or disorder. These GPCRs have recently been reviewed in detail [20]. The GPCRs in Table 1 are all Class A, rhodopsin-like GPCRs. Class A orphan GPCRs not listed in Table 1 are putative GPCRs with as-yet unidentified endogenous ligands.

Table 1: Class A orphan GPCRs with putative endogenous ligands

GPR3	GPR4	GPR6	GPR12	GPR15	GPR17	GPR20
GPR22	GPR26	GPR31	GPR34	GPR35	GPR37	GPR39
GPR50	GPR63	GRP65	GPR68	GPR75	GPR84	GPR87
GPR88	GPR132	GPR149	GPR161	GPR183	LGR4	LGR5
LGR6	MAS1	MRGPRD	MRGPRX1	MRGPRX2	P2RY10	TAAR2

In addition the orphan receptors GPR18, GPR55 and GPR119 which are reported to respond to endogenous agents analogous to the endogenous cannabinoid ligands have been grouped together (GPR18, GPR55 and GPR119).

* Key recommended reading is highlighted with an asterisk

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Stephen P.H. Alexander Associate Professor in Molecular Pharmacology Life Sciences E Floor University of Nottingham Medical School Nottingham NG7 2UH UK Jim Battey (BB3) National Institute on Deafness and Other Communication Disorders Building 31 Room 3C02 NIH Bethesda MD 20892 USA Helen E. Benson (Past curator) Centre for Discovery Brain Sciences Edinburgh Medical School: Biomedical Sciences Room 338 Hugh Robson Building George Square Edinburgh EH8 9XD UK Richard V. Benya (BB3) University of Illinois Section of Digestive Diseases and Nutrition 840 South Wood Street (M/C 716) Chicago Illinois 60612 USA Tom I. Bonner Special Volunteer Office of Science Director NIMH Bethesda MD USA Anthony P. Davenport Experimental Medicine and Immunotherapeutics University of Cambridge Level 6, Addenbrooke's Centre for Clinical Investigation (ACCI) Box 110, Addenbrooke's Hospital Cambridge, CB2 0QQ UK Khuraijam Dhanachandra Singh Department of Molecular Cardiology Lerner Research Institute The Cleveland Clinic Foundation 9500 Euclid Ave. Cleveland, OH 44195 USA Satoru Eguchi Cardiovascular Research Center Temple University School of Medicine 3500 N Broad Street Philadelphia PA 19140 USA Anthony Harmar (1951-2014) formerly of the University of Edinburgh, Edinburgh, Scotland Nick Holliday Room CS6 The Medical School, Floor C Queen's Medical Centre Nottingham NG7 2UH UK Robert T. Jensen (BB3) National Institute of Diabetes & Kidney Diseases National Institutes of Health Building 10 Room 9C-103 NIH Bethesda MD 20892 USA Sadashiva Karnik (MAS1) Department of Molecular Cardiology Lerner Research Institute The Cleveland Clinic Foundation 9500 Euclid Ave. Cleveland, OH 44195 USA Evi Kostenis (GPR17) Section Molecular, Cellular and Pharmacobiology Institute for Pharmaceutical Biology University of Bonn Nussallee 6 53115 Bonn Germany Wen Chiy Liew (Past curator) Amy E. Monaghan (Past curator) Chido Mpamhanga (Past curator) Richard Neubig Michigan State University 1355 Bogue St B440 Life Sciences Building East Lansing MI 48824 Adam J. Pawson (Senior Database Curator) Centre for Discovery Brain Sciences Edinburgh Medical School: Biomedical Sciences Room 338, Hugh Robson Building George Square Edinburgh, EH8 9XD Jean-Philippe Pin Institut de Génomique Fonctionnelle UMR 5203 CNRS – U 1191 INSERM – Univ. Montpellier 141 rue de la cardonille 34094 Montpellier Cedex 05 - France Joanna L. Sharman (Past senior developer) Centre for Discovery Brain Sciences Edinburgh Medical School: Biomedical Sciences Room 338 Hugh Robson Building George Square Edinburgh EH8 9XD UK Michael Spedding Spedding Research Solutions SARL 6 Rue Ampere Le Vesinet 78110 France Eliot Spindel (BB3) Oregon National Primate Research Center Division of Neuroscience 3181 SW Sam Jackson Park Road Portland OR 97239 USA Leigh Stoddart Division of Biochemistry and Molecular Biology Institute of Biomedical and Life Sciences University of Glasgow Glasgow G12 8QQ UK Laura Storjohann (GPR39) Salt Lake City UT 84124 Walter G. Thomas School of Biomedical Sciences The University of Queensland BNE, QUEENSLAND 4072 Australia Kalyan Tirupula (MAS1) Department of Molecular Cardiology Lerner Research Institute The Cleveland Clinic Foundation 9500 Euclid Ave. Cleveland, OH 44195 USA Patrick Vanderheyden Department of Molecular and Biochemical Pharmacology Vrije Universiteit Brussel Pleinlaan 2 1050, Brussels Belgium