TDAG8 (for T-cell death-associated gene 8) is a seven transmembrane G protein-coupled receptor (GPCR) that was originally identified from a human thyroid cDNA library and subsequently shown to be expressed predominantly in thymus, lymph nodes, peripheral blood leukocytes and spleen. TDAG8, which is alternatively designated GPCR25, is grouped collectively with other GPCRs that are induced during T cell receptor engagement-mediated apoptosis and T cell activation, which also include G2A (for G2 accumulation) and P2Y2 (for P2 nucleotide) receptor.