The enzyme, characterized from the yeasts Kluyveromyces lactis and Candida albicans [1] and from the diatom Thalassiosira pseudonana [2], introduces a trans double bond at the 8-position of sphingoid bases in sphingolipids. The enzyme determines the position of the double bond by its distance from the alcohol end of the sphingoid base, and contains a cytochrome b5 domain that acts as the direct electron donor to the active site of the desaturase [3]. The homologous enzymes from higher plants, EC 1.14.19.29, sphingolipid 8-(E/Z)-desaturase, act on phytosphinganine (4-hydroxysphinganine) and produces a mixture of trans and cis isomers.
