http://www.creativebiomart.net/description_382718_12.htm

PTGDS, also known as L-PGDS, is a member of the calycin superfamily, lipocalin family. It is abundantly expressed in the heart, brain, and central nervous system(CNS), where it is expressed in tissues of the blood-brain barrier and secreted into the cerebro-spinal fluid. PTGDS is a glutathione-independent prostaglandin D synthase that catalyzes the conversion of PGH2 to PGD2. It is involved in a variety of CNS functions, such as sedation, NREM sleep and PGE2-induced allodynia, and may have an anti-apoptotic role in oligodendrocytes. It binds small non-substrate lipophilic molecules, including biliverdin, bilirubin, retinal, retinoic acid and thyroid hormone, and may act as a scavenger for harmful hydrophopic molecules and as a secretory retinoid and thyroid hormone transporter.