The function of HPGDS (hematopoietic prostaglandin D synthase, ENSG00000163106) is as follows. Bifunctional enzyme which catalyzes both the conversion of PGH2 to PGD2, a prostaglandin involved in smooth muscle contraction/relaxation and a potent inhibitor of platelet aggregation, and the conjugation of glutathione with a wide range of aryl halides and organic isothiocyanates. Also exhibits low glutathione-peroxidase activity towards cumene hydroperoxide. {ECO:0000269|PubMed:10824118, ECO:0000269|PubMed:11672424, ECO:0000269|PubMed:12244105, ECO:0000269|PubMed:12627223, ECO:0000269|PubMed:15113825, ECO:0000269|PubMed:16547010, ECO:0000269|PubMed:19939518, ECO:0000269|PubMed:9353279, ECO:0000269|PubMed:9425264}.