Description_x000D_ Biochem/physiol Actions_x000D_ Glutathione S-transferase sigma 1, also know as hematopoietic prostaglandin D synthase (HPGDS) is an enzyme that in humans is encoded by the HPGDS gene. Glutathione S-transferases (GSTs) are a family of enzymes that play an important role in detoxification by catalyzing the conjugation of many hydrophobic and electrophilic compounds with reduced glutathione. Based on their biochemical, immunologic, and structural properties, cytosolic and membrane-bound forms of glutathione S-transferase are encoded by two distinct supergene families. At present, eight distinct classes of the soluble cytoplasmic mammalian glutathione S-transferases have been identified: alpha, kappa, mu, omega, pi, sigma, theta and zeta. The GSTs are thought to function in xenobiotic metabolism and play a role in susceptibility to cancer, and other diseases._x000D_ Prostaglandin-D synthase is a sigma class glutathione-S-transferase family member. The enzyme catalyzes the conversion of PGH2 to PGD2 and plays a role in the production of prostanoids in the immune system and mast cells. The presence of this enzyme can be used to identify the differentiation stage of human megakaryocytes._x000D_ Storage and Stability_x000D_ The enzyme should be used by the end-user customer within 1 year of receipt.