The function of Ensembl gene identifier ENSG00000143198 (MGST3, microsomal glutathione S-transferase 3) is as follows. Displays both glutathione S-transferase and glutathione peroxidase activities toward oxyeicosanoids, as part of cellular detoxification as well as synthesis of bioactive metabolites (PubMed:36370807, PubMed:9278457). Catalyzes conjugate addition of reduced glutathione to the alpha, beta-unsaturated C=C carbonyl group of eisosanoids such as leukotriene A4 and 15-deoxy-Delta12,14- prostaglandin J2 to form GSH adducts relevant to the inflammatory response (PubMed:36370807, PubMed:9278457). Catalyzes glutathione- dependent reduction of eicosanoid peroxides to yield the corresponding eicosanoid hydroxides (PubMed:9278457). {ECO:0000269|PubMed:36370807, ECO:0000269|PubMed:9278457}.