dihydroceramide + NADPH + H+ + O2 => phytoceramide + NADP+ + H2O Authored: D'Eustachio, P, 2009-08-20 DEGS2 (sphingolipid C4-hydroxylase 2 / “degenerative spermatocyte homolog 2”) enzyme associated with the cytosolic face of the endoplasmic reticulum catalyzes the hydroxylation of dihydroceramide to form phytoceramide (Mizutani et al. 2004). Sequence similarity to the bifunctional mouse DEGS2 enzyme suggests that human DEGS2 protein might also catalyze the C4-dehydrogenation of dihydroceramide, but this hypothesis has not been tested experimentally. Edited: D'Eustachio, P, 2009-08-20 Pubmed15063729 Reactome Database ID Release 43428260 Reactome, http://www.reactome.org ReactomeREACT_19258 Reviewed: Hannun, YA, Luberto, C, 2009-11-18 Reviewed: Jassal, B, 2009-08-20