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. P2RY8 (purinergic receptor P2Y, G-protein coupled, 8), also known as P2Y8, is a 359 amino acid multi-pass membrane protein that localizes to the cell membrane and belongs to the G protein-coupled receptor family. Expressed at low levels in lung, heart and kidney, P2RY8 may function as a receptor for purines that are coupled to G proteins and may also play a role in mental retardation.