Catalyzes the NAD(P)(+)-dependent oxidative decarboxylation of the C4 methyl groups of 4-alpha-carboxysterols in post-squalene cholesterol biosynthesis (By similarity). Also plays a role in the regulation of the endocytic trafficking of EGFR (By similarity).
Subcellular locations: Endoplasmic reticulum membrane, Lipid droplet
Trafficking through the Golgi is necessary for ER membrane localization.
Brain, heart, liver, lung, kidney, skin and placenta.