The function of PTGES (prostaglandin E synthase, ENSG00000148344) is as follows. Terminal enzyme of the cyclooxygenase (COX)-2-mediated prostaglandin E2 (PGE2) biosynthetic pathway. Catalyzes the glutathione-dependent oxidoreduction of prostaglandin endoperoxide H2 (PGH2) to prostaglandin E2 (PGE2) in response to inflammatory stimuli (PubMed:10377395, PubMed:10869354, PubMed:12244105, PubMed:12460774, PubMed:12672824, PubMed:18682561). Plays a key role in inflammation response, fever and pain (By similarity). Also catalyzes the oxidoreduction of endocannabinoids into prostaglandin glycerol esters and PGG2 into 15-hydroperoxy-PGE2 (PubMed:12244105, PubMed:12672824). In addition, displays low glutathione transferase and glutathione- dependent peroxidase activities, toward 1-chloro-2,4-dinitrobenzene and 5-hydroperoxyicosatetraenoic acid (5-HPETE), respectively (PubMed:12672824). {ECO:0000250|UniProtKB:Q9JM51, ECO:0000269|PubMed:10377395, ECO:0000269|PubMed:10869354, ECO:0000269|PubMed:12244105, ECO:0000269|PubMed:12460774, ECO:0000269|PubMed:12672824, ECO:0000269|PubMed:18682561}.