Prostaglandin D synthase catalyzes the conversion of prostaglandin H2 (PGH2) to postaglandin D2 (PGD2).
Prostaglandin D synthase induces sleep, regulates nociception, inhibits platelet aggregation, and acts as an allergic mediator. Two distinct types of PGD synthase have been identified, namely the lipocalin type enzyme (b-trace) and the hematopoietic enzyme. Lipocalin type prostaglandin D synthase is localized in the central nervous system and male genital organs of various mammals and the human heart. This enzyme has been identified as b-trace, which is a major protein in human cerebrospinal fluid. Hematopoietic prostaglandin D synthase is widely distributed in the peripheral tissues and is localized in the antigen-presenting cells, mast cells, and megakaryocytes.