4-methylcholesta-8(9),24-dien-3beta-ol is oxidized to 4-carboxycholesta-8(9),24-dien-3beta-ol 4-methylcholesta-8(9),24-dien-3beta-ol + 3 NADPH + 3 H+ + 3 O2 => 4-carboxycholesta-8(9),24-dien-3beta-ol + 3 NADP+ + 4 H2O 4-methylcholesta-8(9),24-dien-3beta-ol, NADPH + H+, and O2 react to form 4-carboxycholesta-8(9),24-dien-3beta-ol, NADP+, and H2O. This reaction, in the endoplasmic reticulum, is catalyzed by SC4MOL (C-4 methylsterol oxidase). The human enzyme has been identified based on its sequence similarity to yeast methyl sterol oxidase (ERG25) and the ability of the cloned human gene to rescue ERG25-deficient yeast cells (Li and Kaplan 1996). The mechanism and stoichiometry of the reaction have been inferred from studies of partially purified rat enzyme (Gaylor et al. 1975; Fukushima et al. 1981). Authored: D'Eustachio, P, 2007-04-21 18:31:40 EC Number: 1.14.13.72 Edited: D'Eustachio, P, 2007-04-21 18:31:40 Pubmed240818 Pubmed7228857 Pubmed8663358 Reactome Database ID Release 43194669 Reactome, http://www.reactome.org ReactomeREACT_10059 Reviewed: Jassal, B, 2007-04-21 18:33:24 has a Stoichiometric coefficient of 3 has a Stoichiometric coefficient of 4