Receptor for prostaglandin D2 (PGD2). The activity of this receptor is mainly mediated by G(s) proteins that stimulate adenylate cyclase, resulting in an elevation of intracellular cAMP. A mobilization of calcium is also observed, but without formation of inositol 1,4,5-trisphosphate (By similarity). Involved in PLA2G3-dependent maturation of mast cells. PLA2G3 is secreted by immature mast cells and acts on nearby fibroblasts upstream to PTDGS to synthesize PGD2, which in turn promotes mast cell maturation and degranulation via PTGDR (By similarity). Expressed in retinal choroid, ciliary epithelium, longitudinal and circular ciliary muscles, iris, small intestine and platelet membranes. Disease susceptibility is associated with variants affecting the gene represented in this entry. Belongs to the G-protein coupled receptor 1 family.