G protein-coupled receptor 27 (GPR27) is a member of the G protein-coupled receptors (GPCRs), a large family of receptors that have a similar structure characterized by 7 transmembrane domains. Activation of GPCRs by extracellular stimuli such as neurotransmitters, hormones, or light induces an intracellular signaling cascade mediated by heterotrimeric GTP-binding proteins, or G proteins. GPR27 is characterized by a high level of conservation among vertebrates and a predominant expression in the central nervous system. In addition, it has recently been linked to insulin secretion. References: Molecular Pharmacology June 2017, 91 (6) 595-608;