Background
G protein-coupled receptors (GPRs), also known as seven transmembrane receptors, heptahelical receptors or 7TM receptors, comprise a superfamily of proteins that play a role in many different stimulus-response pathways. G protein-coupled receptors translate extracellular signals into intracellular signals (G protein activation) and they respond to a variety of signaling molecules, such as hormones and neurotransmitters. GPR68 (G protein-coupled receptor 68), also known as OGR1 (ovarian cancer G-protein coupled receptor 1), is a 365 amino acid multi-pass membrane protein that is expressed in testis, spleen, lung, brain and placenta. Existing as a member of the G protein-coupled receptor family, GPR68 functions as a high affinity receptor for sphingosylphosphorylcholine and is coupled to G proteins that enhance phosphoinositide hydrolysis.